Using Automated Image Analysis for Characterization of Additive Manufacturing Powders
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The metallic powders used as feedstock for the additive manufacturing process require evaluation of several morphological and chemical composition characteristics to ensure predictable material behavior during the manufacturing process and performance in use. The size, shape, and internal porosity of the particles are several traits requiring evaluation. Often, numerical estimates representing these characteristics are made using the digital images generated with X-ray computed tomography (CT) scans or automated image analysis (AIA). Image analysis offers several advantages over CT scans. These include lower equipment and individual test costs, higher image resolution due to higher system magnifications, and faster analysis time. In addition to the morphological analyses, particle-to-particle
chemical composition uniformity is essential to maintaining the proper part microstructure. A procedure using a scanning electron microscope equipped with an energy dispersive spectrometer is described to determine the presence of particle cross-product contamination and any foreign materials.
(2.73 mb)
Metallographic Testing of Titanium Parts Made by Additive Manufacturing
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An integral part of producing titanium parts by additive manufacturing (AM) is providing test data that demonstrate the quality, uniformity, and consistency of the products. Typically, chemical, mechanical, physical, and metallographic tests are performed to ensure parts meet or exceed the expectations and requirements of each application. Each test discipline provides unique information on the properties and expected behavior of the AM produced parts. The contributions of metallographic testing on quantifying some of the attributes of the parts are discussed in this paper. The microstructural constituents of internal porosity, nonmetallic inclusion content, and surface texture are evaluated and discussed. Light optical microscopy using automated image analysis (IA) and stereomicroscopy techniques are employed in this
analysis.
(1.82 mb)
Advancements in Insulated Powder Composites for Soft Magnetic Applications
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(364 kb)
Monitoring of Powder Homogeneity During Double-Cone Blending
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(994 kb)
Enhanced Processing Developments in Steel Powders
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(1.46 mb)
New Machinability System for PM Steels
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(314 kb)
New Machinability Additive for PM Steels
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(2.62 mb)
Sensitivity Analysis of Machining Parameters in Fe-Cu-C Mixes Containing Machining Enhancers
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(652 kb)
Machinability response of PM steels with varying levels of alloy content
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(235 kb)
Improving Machinability of PM Components; Examining the stability of additives and machinability best practices
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(763 kb)
Investigation Into Machinability Improvements For FC-0208
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(1.58 mb)
Improving Machinability of PM Components via New Additive Compound
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(864 kb)
Improving Machinability of PM Components: Response of Novel Machining Additive and Predictability Analysis of Machining Behavior
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(1.30 mb)
Characterization of a Novel Machining Additive in Diffusion-Alloyed Mixes: Sensitivity Analysis of Tool Life, Machining Quality and Wear Dynamics
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(461 kb)
Additives for Improved Machining of Copper PM Steels
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(1.43 mb)
Production Experience with High Consistency FC-0208 Material Made Using Advanced Bonding Technology
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(3.15 mb)
Prealloyed PM Steels
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(238 kb)
Vanadium and Silicon Alloyed PM Steels
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(886 kb)
The Effect of Bonding Method on the Properties of Low Alloy PM Steels
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(1.56 mb)
Influence of Alloy Selection on Manufacturing Precision PM Components
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(842 kb)
Salt Spray and Immersion Corrosion Testing of PM Stainless Steel Materials
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(788 kb)
Microstructure and Properties of Hybrid-Alloy Chromium Steels
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(1.10 mb)
Microstructure and Mechanical Properties of a Bainitic PM Steel
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(2.67 mb)
Microstructure and Mechanical Properties of PM Steels Alloyed with Silicon and Vanadium
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(1.87 mb)
Microstructure and Mechanical Properties of Microalloyed PM Steels
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(1.28 mb)
Mechanical Properties of PM Alloy Systems with Silicon and Vanadium Additions
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(565 kb)
Sinter-Hardening Response of a Lean Sinter-Hardening Alloy
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(1.81 mb)
Leaner Alloys for the PM Industry
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(434 kb)
Influence of Alloy Selection on Manufacturing Precision PM Components
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(842 kb)
Hardenability Response of Fe-Mo-Ni-C Powder Metallurgy Alloys
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(632 kb)
Dimensional Control in Powder Metal Parts
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(1.39 mb)
Fatigue Performance of Molybdenum Prealloyed PM Steels
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(2.57 mb)
Cost-Effective / High-Performance Lean Alloys
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(1.66 mb)
Axial Fatigue Properties of Lean Fe-Mo-Ni Alloys
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(1.51 mb)
A Metallographic Examination into Fatigue Crack Initiation and Growth in Ferrous PM Materials
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(2.71 mb)
Double Press Double Sinter Alternatives for High Density Applications
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(1.14 mb)
Warm Die Compaction with Reduced Lubricant Levels Promoting Higher Green and Sintered Densities
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(299 kb)
Warm Die Compaction of a High Density Crankshaft Sprocket
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(425 kb)
Warm Compaction and Warm-Die Compaction of Ferrous PM Materials
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(1.73 mb)
Method to Reduce Die Wear Caused by Abrasive Hard Particle PM Additives
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(550 kb)
Diffusion-Alloyed Steels for High Performance Applications
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(1.30 mb)
Production Experience with High Consistency FC-0208 Material Made Using Advanced Bonding Technology
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(2.41 mb)
Production of High Density PM Automotive Components Utilizing Advanced Warm Die Compaction Technology
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(790 kb)
Warm Die Compaction of a High Density Crankshaft Sprocket
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(398 kb)
Improving the Sintered Dimensional Response of FC-0208 for Applications Requiring Restrictive Dimensional Control after Sintering
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(1.18 mb)
Dimensional Precision of Fe-Cu-C Premixes
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(1.18 mb)
Development of a Lubricant System for Improved Performance of Premixes
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(562 kb)
Effect of Impurities on Aging of Sintered Soft Magnetic Materials
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(858 kb)
Novel Soft Magnetic Composite for AC Applications with Reduced Total Core Losses
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(362 kb)
Newly Developed Soft Magnetic Composites for AC Applications with Reduced Iron Losses
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(763 kb)
Iron-Silicon Water Atomized Powders for Electromagnetic Applications
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(241 kb)
Elevated-Strength Soft Magnetic Powder Metal Materials and Processing
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(1.30 mb)
Effect of Particle Size and 2P2C Technology on the Soft Magnetic Properties of Composite Iron Compacts
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(451 kb)
Al2O3 and Fe3O4 Coated SMCs: Effect of Coating Material and Milling Time on Magnetic and Mechanical Properties
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(436 kb)
Development of New Soft Magnetic Composite Material Possessing Higher Levels of Magnetic and Mechanical Performance
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(255 kb)
Development of a New High Density AC Magnetic Material Possessing Good AC Magnetic Performance with Enhanced Mechanical Strength
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(190 kb)
Economic Additive Manufacturing using Water Atomized Stainless Steel Powder
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Zwiren, A. and Schade, C.
(1.38 mb)
Comparison of Binder Jetting Additive Manufacturing to Press and Sinter 316L Stainless Steel
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Zwiren A. and Murphy, T. F.
(1.72 mb)
Titanium Alloy Development for AM Utilizing Gas Atomization
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Schade, C.; Murphy T. and Bernhard G.
(1.44 mb)
EffectofParticleSizeand2P2CTechontheSoftMagneticPropofCompositeIronCompacts.pdf
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(571 kb)
Monitoring of Powder Homogeneity During Double-Cone Blending - 2018 Howard I. Sanderow Outstanding Technical Paper Award
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A challenge central to the Powder Metallurgy (PM) process is achieving consistent and uniform products. A crucial step in reaching this goal, is ensuring powder blending sufficiently homogenizes a mix. A challenge to powder and parts producers is creating a process that both achieves homogeneity and operates efficiently. C-Therm’s ESP technology offers a window into the blender by measuring the thermal properties of powder during processing. Powder chemistry and density have a significant impact on the thermal properties and measuring thermal effusivity repeatedly throughout processing can indicate once a stable, homogenous blend has been achieved. The authors seek to establish the usability and accuracy of measuring effusivity by monitoring multiple blend conditions and comparing results to standard industry methods such as thief sampling.
(999 kb)
Comparison of Binder Jetting Additive Manufacturing to Press and Sinter 316L Stainless Steel - APMI Excellence in Metallography Award
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Although the fabrication method of Binder Jetting Additive Manufacturing (AM) is completely different to typical compaction methods in traditional Powder Metallurgy (PM); the technological intersection is a need for sintering of the “green” parts. In this study, comparisons are made between the two production methods in regards to their overall density, mechanical properties, microstructure, and pore structure as a result of sintering variations. Vacuum sintered binder jetting 316L mechanical test samples exhibited robust mechanical properties in relation to the sintered density (7.3 g/cm3) of the tested sample due to the unique combination of fine powder size (D50~ 10 μm), production method, and sintering method. This is analyzed and explained through porosity and microstructural analyses in comparison to typical press and sinter results. The sintering conditions in this study vary from sintering via vacuum furnace, tube furnace, and belt furnace; sintering in temperature ranges from 1260 °C to 1380 °C in two hydrogen atmosphere conditions, a hydrogen partial pressure and 100% hydrogen.
(1.73 mb)
Using Light and Electron Microscopy, Computed Tomography, and Light Scattering to Evaluate Additive Manufacturing Powders and Parts - AMPM 2018 Best Paper Award
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Customized test techniques using combinations of light and electron microscopy, computed tomography, and light scattering have been developed to evaluate the characteristics of both the powder feedstocks used in additive manufacturing and the finished parts. By combining these techniques, a more accurate assessment of additive manufacturing products is possible because each provides specialized benefits to the evaluation. Some are limited to individual types of data, while others are more versatile and provide information in several areas of interest. The high-resolution capabilities of the microscopy techniques increase the accuracy of linear and areal measurements and the scanning electron microscopy enhancement of performing chemical analysis provides additional unique benefits. Computed tomography has the ability to view particles and parts as three-dimensional features, finding internal defects, porosity, etc. The light scattering methods are valuable in being able to estimate particle size into the range from nanometer to millimeter. This technical paper will present both benefits and drawbacks of these techniques in hopes of finding the best combination of tests to characterize the additive manufacturing materials and products efficiently and accurately.
(2.47 mb)
Using Light and Electron Microscopy, Computed Tomography, and Light Scattering to Evaluate Additive Manufacturing Powders and Parts
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AMPM2018 Best Paper Award: Customized test techniques using combinations of light and electron microscopy, computed tomography, and light scattering have been developed to evaluate the characteristics of both the powder feedstocks used in additive manufacturing and the finished parts. By combining these techniques, a more accurate assessment of additive manufacturing products is possible because each provides specialized benefits to the evaluation. Some are limited to individual types of data, while others are more versatile and provide information in several areas of interest. The high-resolution capabilities of the microscopy techniques increase the accuracy of linear and areal measurements and the scanning electron microscopy enhancement of performing chemical analysis provides additional unique benefits. Computed
tomography has the ability to view particles and parts as three-dimensional features, finding internal defects, porosity, etc. The light scattering methods are valuable in being able to estimate particle size into the range from nanometer to millimeter. This technical paper will present both benefits and drawbacks of these techniques in hopes of finding the best combination of tests to characterize the additive
manufacturing materials and products efficiently and accurately.
(2.46 mb)
Development of Nitinol Alloys for Additive Manufacturing
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Nickel-titanium (Nitinol) shape memory alloys exhibit unique properties, such as the
shape memory effect and superelasticity. The shape memory effect occurs when the alloy is deformed in the martensitic state then heated above its transformation temperature where it reverts to austenite and returns to its original shape. The role of gas atomization parameters, chemical composition, and particle size distribution of Nitinol powder are studied in relation to the transformation temperature. Typical particle sizes utilized in selective laser melting (SLM) and directed energy deposition (DED) additive manufacturing (AM) processes are examined. The influence of re-melting the powder and the subsequent solidification effects, as would be seen in SLM, are studied in relation to the transformation temperature. (2017)
(663 kb)
Advances in Binder-Treatment Technology Statistical Data on Ancorbond Plus
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Binder treatment technology has been well accepted in the marketplace to provide
reduced segregation and better powder flowability. However, there is a need to increase the green strength of some parts for better handling of intricate shapes and also a need to improve the bonding of nickel and copper. ANCORBOND Plus is an engineered bonding technology that can produce very high green strength and green density based on conventional compaction processing. The system, which uses a zincless lubricant, is based on the optimization of the bonding mechanism and binder chemistry. This paper will present statistical data collected on parts processed in a production press. (2000)
(93 kb)
High Performance PM Stainless Steels
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Powder Metallurgy (P/M) automotive exhaust flanges are in volume production for
several US automobile and light truck engines. However competing technologies
continue to improve and may threaten the anticipated increase in applications of P/M
stainless flanges. This paper examines the properties of stainless steel powders,
particularly a stabilised ferritic steel that should improve the processing and
competitiveness of P/M stainless steels in automotive applications. (1999)
(57 kb)
The Effect of Microstructure and Pore Morphology on Mechanical and Dynamic Properties of Ferrous PM Materials
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The objective of this study was to quantify and understand the combined role of microstructure and pore characteristics on the transverse rupture strength (TRS), tensile properties and rotating bend fatigue response of conventional and ANCORDENSE processed FLN2-4405 premixes. To this end, the premixes were made with samples using fine (4μm) and coarse (50μm) nickel powder to promote differences in pore size and diffusion characteristics. Compacts were sintered in synthetic DA (75 v/o H2 / 25 v/o N2) at 2050°F (1120°C) or 2300°F (1260°C) to densities in the range of 6.8 g/cm³ - 7.2 g/cm³. Pore size and spacing, cumulative
pore size and number of pores per unit area were determined by stereological analysis, and the crack path was monitored by means of optical microscopy. The static and dynamic properties of the materials made from the two premixes are interpreted in terms of the attendant microstructures and pore characteristics, as dictated by the premix type, sintering temperature and sintered density. (1999)
(709 kb)
Performance Characteristics of a New Water-Atomized Prealloyed Powder (0.5 Weight Per Cent Molybdenum)
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A new prealloy material containing 0.50 w/o Mo was introduced recently. This medium
hardenability material can be admixed with a variety of alloying ingredients to produce superior tensile properties. Results of admixing this prealloyed powder with nickel, copper, manganese, and graphite will be presented. In addition, quench and temper properties will also be discussed. (1999)
(98 kb)
A Comparison of Ancordense Processed Materials with Malleable Cast Iron
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A study was conducted that compared the mechanical properties of a series of
ANCORDENSE prepared materials with malleable cast iron. This paper will present the
mechanical properties (TRS, tensile, impact, and fatigue) of various ANCORDENSE preparedpremixes in the as sintered condition compared with a malleable cast iron. The objective of this investigation was to demonstrate that an engineered P/M material coupled with ANCORDENSE processing can replace a malleable cast iron component giving equivalent mechanical property performance and potentially equivalent gear performance. (1999)
(61 kb)
A Superior Sinter-Hardenable Material
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Sinter-hardening technology has been assisting the P/M parts fabricator by improving
processing efficiencies and reducing costs. Furthermore, the barriers to attaining good sinterhardenability and part performance have been reduced through improvements in materials and equipment developments. Recent material advances have focused on new alloys with increased hardenability and compressibility. A new sinter-hardenable alloy has been introduced which provides improvements in hardenability and compressibility over the well-established FLC-4608 composition. These improvements will allow fabricators to reach higher densities and mechanical performance under typical compaction and sintering conditions. Mechanical performance and material capabilities are investigated as a function of density and admixed composition. Additional processing to achieve higher green densities and mechanical performance will also be reviewed. (1999)
(1.57 mb)
Ancorloy Premixes - Binder Treated Analogs of the Diffusion Alloyed Steels
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The properties at two carbon levels of binder treated analogs of the diffusion alloyed steels are presented. These Ancorloy premixes are made according to a proprietary practice that does not include diffusion alloying. It is shown by direct comparison with compositionally similar premixes of the diffusion alloyed steels that the Ancorloys generally exhibit similar powder, green and dimensional change properties and significantly enhanced mechanical properties. Tensile, impact and fatigue property data in the sintered, sintered and tempered and quenched and tempered conditions are presented. (1999)
(163 kb)
What Is Sinter-Hardening?
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The mechanical properties of ferrous powder metallurgy (P/M) materials are directly
related to their density and microstructure. Many PIM parts are heat treated, in a
secondary operation, to develop a tempered martensitic microstructure either in a
surface layer, or throughout the part. The need for a secondary quenching operation
may be avoided by "sinter-hardening" the parts. Ferrous P/M materials with sufficient hardenability will develop microstructures containing significant percentages of martensite in the as-sintered condition. Accelerated cooling · techniques for sintering furnaces have been developed which permit larger parts to be sinter-hardened, or materials with lower hardenability to be Used to produce sinter-hardened parts with smaller cross-sections. The difference between hardness and hardenability will be explained and a review presented of how the alloying method selected for ferrous P/M materials influences hardenability. Examples of sinter-hardenable materials will be provided and the benefits and disadvantages of the sinter-hardening process will be discussed. (1998)
(976 kb)
Application of High Performance Material Processing - Electromagnetic Products
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The use of powder metallurgy (P/M) parts in AC applications is limited by the inability to reduce the total core loss of the P/M components to levels achieved with conventional laminations. The use of iron powder polymer composites has proven successful in high frequency applications such as ignition coils and high-speed motors. Broader application of P/M in AC applications will require a metedal that will provide superior magnetic performance at low frequencies. This paper will discuss the use of high performance materials for DC applications (in particular, alloys of iron and
silicon) as well as the use of insulated powders for both high and Low frequency applications. (1998)
(679 kb)
Application of High Performance Materials and Processes - Alloy Systems
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Significant advances have been made in the past several years in developing Low alloy materials for highly stressed applications. A review of these material and processing developments will be made. Recent material developments focus on developing high apparent hardness and tensile strength in P/M parts without the need for a secondary quench-hardening operation. The effect of alloy type, alloy
content, and cooling rate on hardness and other properties will be discussed. (1998)
(927 kb)
The Effect of Microstructure and Pore Morphology on Mechanical and Dynamic Properties of Ferrous PM Materials
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Fatigue testing was performed on FN-0205 premixes in order to evaluate the effect of pore structure and processing method on the fatigue properties. The premixes were made with two nickel sources:
· mean particle size of 4 mm
· mean particle size of 50 mm
Metallographic analysis was performed to quantify the pore structure. The following parameters were examined: pore size, pore shape, mean pore spacing and average pore size. Previous work, which examined a variety of materials, indicated that predicting the fatigue strength of a material is a complex relationship between the type and strength of the microstructural constituents, as well as stereological parameters such as mean pore spacing and pore size. This paper attempts to determine to what extent each of the above parameters influences the fatigue strength of P/M materials. (1998)
(642 kb)
Higher Green Strength and Improved Density by Conventional Compaction
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A new material system that can produce very high green strength and green density has been developed for conventional compaction processing. The system, which uses a zincless lubricant, is based on the optimization of the bonding mechanism and binder chemistry. This approach permits the bonding of copper particles in a FC-0208 mix. Examples of the binder-treatment of FN-0208, Ancorstee145P, and Ancorstee150
HP are also included. (1998)
(1.55 mb)
Applications of High Performance Binder Treated Materials
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Binder treated materials such as ANCORBOND® and ANCORDENSE® increase the performance characteristics of ferrous powder premixes and P/M parts. This paper will discuss the various characteristics of binder treated premixes and their potential applications. A review of the mechanical properties of ANCORDENSE materials will be presented. (1998)
(369 kb)
The Application of Warm Compaction to High Density Powder Metallurgy Parts
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The warm compaction process (ANCORDENSE®) has been shown to provide increased density in ferrous powder metallurgy parts. This improvement in density contributes significantly to mechanical properties and thus the overall performance of the part. The combination of increased density with high performance material selections, provides parts that can exceed the performance of forged or cast material counterparts while taking advantage of powder metallurgy's net shape forming capabilities. Turbine hubs for automatic transmission torque converters have
proven to be ideal candidates for the powder metallurgy (P/M) process. The complex shape of turbine hubs is costly to produce via conventional forging and machining operations. However, increases in engine size and torque requirements in several
automotive designs have required that turbine hubs possess higher levels of mechanical properties. High density P/M manufacturing techniques, in combination with high performance ferrous materials produces components capable of replacing a forged and machined turbine hub. This paper will review the conversion of a conventionally forged and machined turbine hub used in a high torque automatic
transmission to a single pressed and single sintered P/M turbine hub. The material used for the P/M hub was an FD-0405. This diffusion alloyed material was evaluated in the laboratory and mechanical properties are reported at several density levels.
Warm compaction processing achieved high overall sintered densities in the highly stressed internal spline region. Extensive mechanical and part specific testing was conducted to verify the suitability of the P/M part. (1997)
(342 kb)
The Effect of Service Temperature on the Properties of Ferritic PM Stainless Steels
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An area of current development for P/M stainless steel applications is automotive exhaust systems. Recent work in this area has proven the potential application of ferritic stainless steel P/M materials for exhaust flanges to be viable. Lacking in
this work, however, is a sufficient database for P/M stainless steels and, in particular, elevated temperature mechanical properties. A study was undertaken to investigate the effect of service temperature on the mechanical properties of several ferritic P/M
stainless steel grades including 410L, 409Cb, 434L and 434Cb. In particular, tensile properties were generated for these alloys and compared with their wrought equivalents. The effect of process conditions and the subsequent microstructure was also considered. (1997)
(1.15 mb)
Sinter-Hardening PM Steels
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The use of P/M structural parts is growing in part due to the use of the sinter-hardening process which utilizes high performance materials in combination with an accelerated post sintering cooling rate. The sinter-hardening process offers improved
mechanical properties over conventional sintering without a separate heat treatment operation. Thus, where the part design permits, sinter-hardening offers considerable economic benefits to the part producer. Sinter-hardening typically requires that the P/M steel substantially transform to martensite during cooling. A variety of microstructures and properties can be obtained by varying the post sintering cooling rate. By controlling this rate, the microstructure can be manipulated to produce the required amount of martensite to obtain the desired mechanical properties. Alloying elements such as molybdenum, nickel, and copper promote hardenability in P/M parts. By increasing the hardenability of the material, the parts can be cooled at slower rates and still produce large amounts of martensite. The ability to increase the amount of martensite, leading to increased strength and hardness, through the use of proper alloy selection and accelerated cooling rate will be discussed. (1997)
(762 kb)
The Effect of Microstructure on Fatigue Properties of Ferrous PM Materials
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Fatigue testing (rotating bending fatigue) was performed on several materials in order to evaluate the effect of several microstructural elements. Metallographic analysis was performed to characterize the microstructures of the materials and attempt to identify failure mechanisms. Previous work indicated that predicting the fatigue strength of P/M materials is a complex relationship between the grain size of the
material, the type and strength of the microstructural constituents present and, primarily, the mean pore spacing. [1,2] This study examines these relationships in more depth. (1997)
(967 kb)
Processing Experience of Green Strength Enhanced Material Systems
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Green strength enhanced material systems have been developed for iron and Low alloy as well as stainless powder metallurgy applications. Relative to normal processing, the increase in green strength is 50-100%. The nature of green
strength with respect to both materials and processing conditions is reviewed. The processing variations designed to meet target properties such as apparent density, flow and compressibility are compared with conventional material systems. Manufacturing experience with a mechanical press is presented. (1997)
(1.55 mb)
The Effect of Nickel Content, Sintering Temperature and Density on the Properties of a Warm Compacted 0.85 w,o Molybdenum Prealloy
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The combination of molybdenum prealloyed steel powders and admixed nickel provides sintered steels that are used in structural parts requiring strength, wear resistance, and impact toughness. The properties of these materials, like all P/M steels, are dependent on density, microstructure and composition. This work discusses the effect of admixed nickel content, sintering temperature, and density on
the properties of a 0.85 w/o molybdenum prealloy. Samples were prepared with 0, 2, 4 and 6 w/o nickel additions. The materials were warm compacted at 30, 40, 45, and 50 tsi (415, 550, 620 and 690 MPa) and sintered at 1900°F, 2100°F and 2300°F (1040°C, 1150°C, and 1260°C). Mechanical properties were determined and related to the density, microstructure, and composition. (1997)
(1.11 mb)
A Performance Comparison of Current PM Lubricants and Routes to Improvement
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Greater demands are being placed on lubricant performance because of general industry trends toward more intricate part shapes with related tooling complexity and the incorporation of abrasive additives in mixes. To illustrate the significance of these performance demands, it is necessary to identify the role lubricants play in mixing and the P/M part manufacturing process. This work examines the effects of lubricants on material flow, apparent density, compaction, ejection characteristics and sintered properties. The findings identify key performance elements, which provide a model for developing an improved P/M lubricant. A performance comparison with a commercial lubricant highlights the advantages of a composite lubricant that was evaluated. (1997)
(1.38 mb)
The Manufacture of Electromagnetic Components by the Powder Metallurgy Process
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The powder metallurgy process provides the ability to manufacture net shape parts from a variety of materials in a cost effective manner. A market segment that has exhibited the ability to take advantage of powder metallurgy's flexibility has been in
electromagnetic applications. This area has shown significant growth in the past decade that should continue for the foreseeable future. This paper will discuss materials and processes that have proven successful in several electromagnetic applications. Both sintered materials for DC type applications and insulated materials for AC applications will be reviewed along with appropriate processing techniques for each. Specific applications for both materials will be presented. (1997)
(375 kb)
Recent Applications of Binder Treatment Technology
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The development of a practical binder treatment process in the late 1980's has since led to the commercialization of several new premix technologies that have had a major impact on P/M competitiveness. To date, a great deal has been written about
these technologies. However, until now, there has been little to suggest that they are inherently interrelated by a common approach, or that this approach has untapped potential for still newer and better technologies. In addition, it also happens that in spite of all that has been written on the existing technologies, there is nothing that serves as a comprehensive single source of information on all of them. Consequently, the purpose of the present paper is to document the indicated approach as well as to present a summary description of each of the technologies complete with one or more production case histories of recent origin. The aim of the latter is to present discriminating up-to-date examples of general interest as well as
to highlight one or more of the various advantages of the associated technology. (1997)
(542 kb)
Enhanced Green Strength Material System for Ferrous and Stainless PM Processing
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Strength limitations of green powder metallurgy compacts often present fabricators with processing problems. Increased part complexity, process automation and the need for reduced green scrap requires the P/M compact to attain higher green strength. Currently, several limitations restrict the ability to increase green strength in P/M compacts. Powder characteristics, such as particle size distribution and morphology, compressibility and common lubricant systems, all pose limitations on the compact green strength. Enhanced material systems improve the green strength of ferrous-based P/M parts by a minimum of 100% relative to compacts containing admixed lubricant. Process advantages, specific test results, and side effects of high green strength systems will be discussed. (1996)
(1.90 mb)
The Development of High Performance PM Steels
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Ferrous powder metallurgy has continued to displace competing cast or wrought technologies in automotive applications. This required the development of materials systems with higher, more consistent performance than those available previously. However, competing technologies are not static. The paper examines the materials
development and microstructural control required to meet the challenges and opportunities offered by the development of new P/M parts. (1996)
(1.45 mb)
Powder Metallurgy Materials for AC Magnetic Applications
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Ancorsteel Insulated Powders provide the ability to utilize ferrous powder metallurgy materials in alternating magnetic field applications. These materials, unlike sintered components, offer the ability to control eddy current generation at high frequencies. The development process involved in the evolution of these materials is reviewed along with magnetic and physical properties. Potential part applications are presented with special emphasis placed on utilizing powder metallurgy's unique shape making capabilities. (1996)
(91 kb)
Single Compaction to Achieve High Density in Ferrous PM Materials in Automotive Applications
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The continued growth of ferrous powder metallurgy in automotive applications is
dependent on the development of higher density and improved dynamic properties.
New powder metallurgy applications also must be cost effective through the continued use of the process's, net shape forming capabilities and a reduced number of manufacturing steps. The processes utilized to manufacture some of these new parts also must provide the ability to produce thin walled parts with complex geometries. The use of the warm compaction process (ANCORDENSE™) will be shown to develop high density levels with a single compaction process. The process also provides increased green strength and reduced ejection forces. The dependence of mechanical properties on density will be demonstrated. An example of a potential application of the warm compaction technology is an output shaft. The capability of manufacturing this part with the warm compaction process is outlined and compared with the same part made by the double press/double sinter (DPDS) process. Part density and performance from both processes are compared. (1996)
(319 kb)
The Effect of Microstructure on Fatigue Properties of High Density Ferrous PM Materials
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Fatigue testing (rotating bending fatigue) has been performed on several high
performance ferrous P/M material systems. Detailed metallographic analysis was
performed to determine differences in the failure mechanisms for various material and
process combinations. A variety of material compositions were single compacted to
high density via the ANCORDENSE compaction system. This was followed by
conventional and high temperature sintering and testing in the as-sintered and heat
treated conditions. The analysis provides information as to the relationships between
density, structure and composition with fatigue life. (1996)
(945 kb)
Properties of Several Ancordense Processed High Performance Materials
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The effect of powder and compaction temperature on the ANCORDENSE warm compaction system is evaluated. Detailed property analysis is presented on several warm compacted high performance materials systems. Properties evaluated include density, tensile, and impact performance. A detailed assessment of the microstructure resulting from various alloy compositions and processing techniques is performed. The materials involved in the tests were conventional and high temperature sintered and tested in the as sintered and heat treated condition. (1996)
(1.55 mb)
Continuing Improvements in Binder Treatment Technology
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The binder-lubricant concept in which the binder acts to lubricate as well as to bond is introduced. The binder treatment effects on premix properties of an ordinary binder versus one with lubricating properties are compared. It is shown that the lubricating binder is superior in terms of its effects on compressibility and die ejection forces. Otherwise, it is shown to be similar to the ordinary binder in suppressing dusting and
segregation, and improving powder flow. (1996)
(44 kb)
Machinability of PM Steels
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This paper will examine the potential to improve the machinability of sintered P/M steels by the addition of freemachining agents. Testing will examine the effects of freemachining agents upon the sintered properties and machinability in drilling of commercial P/M steels, including FC-0208 or FN-0205. (1995)
(876 kb)
An Investigation into the Effects of Processing Methods on the Mechanical Characteristics of High Performance Ferrous
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The mechanical properties of high performance ferrous P/M materials are influenced by the material composition and processing method. This paper investigates the effects of the ANCORDENSE™ process, a new, high density, single compaction
method, on the mechanical properties of Distaloy® 4800A based materials. The results of this study are discussed with a comparison to the mechanical properties for the same materials developed through single-pressed and double-pressed, doublesintered processing methods. In addition, a case study is performed on a component produced via the ANCORDENSE method. (1995)
(587 kb)
Properties of Diffusion Bonded Alloys Processed To High Densities
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Diffusion bonded alloys have been shown to exhibit excellent properties. Recent advancements in compaction technology have allowed these materials to reach green density levels of over 7.3 g/cm3 in a single compaction process. Various capabilities of this new compaction system will be demonstrated utilizing diffusion bonded alloys. Properties of several diffusion bonded materials will be investigated at these high density levels. A variety of processing techniques will be utilized including high temperature sintering and heat treatment to demonstrate the flexibility of these materials. (1995)
(395 kb)
Advanced Properties of High Density Ferrous Powder Metallurgy Materials
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The introduction of the ANCORDENSE system has provided significantly higher density levels than previously possible in a single press/single sinter operation. This paper will explore the role that higher density has on mechanical properties. Various properties will be evaluated, including transverse rupture strength, tensile strength, and impact.
Additionally, the effect of other processes, such as high temperature sintering and heat treatment, will be addressed. (1995)
(1.47 mb)
Machinability Evaluation of Selected High Green Strength PM Materials
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P/M parts generally require machining methods and specific tools designed to address the inherent porosity of the finished part. The composition and microstructure of sintered parts often causes machining problems and requires additives to enhance machinability. Currently, conventionally produced ferrous P/M parts have an average green strength of approximately 1500-psi. Recent technological advances with organic binders and lubricants, combined with improved compaction technology, have made it possible to produce P/M parts with enhanced green strengths. Enhanced green strength makes it possible to machine materials in the green state, thereby reducing manufacturing time and production costs. This paper examines green drilling by applying several machinability and material evaluation methods. (1995)
(1.46 mb)
Continuous Improvements in Atomized Powders through Team-Oriented Problem Solving
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A “Total Quality System” approach at Hoeganaes allows all employees to participate in achieving the organization's quality goals. The various phases of the quality system from product control, SPC, process documentation, team development, and team oriented process development are reviewed. One example of team-oriented process improvement will be demonstrated using the improvements achieved in the
microcleanliness of atomized products. (1994)
(283 kb)
Laser Welding PM for Automotive Applications
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The ability to laser weld automotive components is a determining factor in converting the currently specified wrought or cast materials to powder metallurgy (P/M) parts for various applications. Material selection, process conditions and joint design are known to have a significant influence when fusion welding P/M components. Welding trials were conducted to determine the appropriate laser parameters for several P/M grades at various density levels. Bead-on-plate, overlap and butt joint designs were attempted, primarily without filler metal additions. (1994)
(690 kb)
Recent Developments in Ferrous Powder Metallurgy Alloys
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A systems approach to engineered ferrous powder metallurgy (P/M) materials is described. The approach encompasses the use of high compressible, high performance powders in premixes produced using proprietary mixing technology that employs patented binders. To ensure that an appropriate microstructure is achieved to suit the functional requirements of a particular application, alloys are formulated based on knowledge of the compaction and sintering cycle that will be used to
make the P/M parts. These premixes have improved flow and die filling characteristics that result in greater consistency throughout the entire P/M part manufacturing process. In addition, the use of binder treated premixes leads to reduced dusting and segregation of alloy additions. Binder treated premixes produced using high compressible, prealloyed molybdenum steel powders are shown to be particularly well suited for quench-hardening, sinter-hardening, and high temperature sintering. They also form the basis for a series of chromium, manganese, and chrome-manganese P/M Steels. The systems approach will be augmented during 1994 by the introduction of new material and process technology that enables part densities of 7.3 to 7.5 g/cm3 to be achieved through single compaction processing. (1994)
(339 kb)
High Density Processing of Cr-Mn PM Steels
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The use of chromium and manganese as alloying elements in P/M steels offers several potential advantages over copper and nickel that are used in conventional P/M alloy steels. The paper will illustrate how the principles used to improve the hardenability
and performance of wrought steels can be applied to P/M chromium and manganese alloy steels using a systems approach. The use of chromium-manganese for P/M applications was made possible by binder-treated premix technology of a highly compressible prealloyed low alloy base material. The flexibility of alloy design will be illustrated by examples of through hardening, high strength low alloy steels. (1994)
(638 kb)
High Density Processing of High Performance Ferrous Materials
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Density is an predominant factor in the performance of powder metallurgy components. Methods such as double press/double sinter, copper infiltration and powder forging have been employed to provide higher densities than traditional single press and sinter operations; however, their widespread use is constrained by cost and geometry considerations. A commercially proven method for obtaining single
compaction/single sinter densities in the 7.25 to 7.55 g/cm3 range by means of the patented ANCORDENSE™ technology is introduced. Conventional compaction pressures and sintering temperatures, typically not exceeding 50 tsi or 2300°F,
respectively, are utilized. Resulting properties for several high performance materials are presented. Test results indicate that the ANCORDENSE process is a cost
effective method of providing high density parts with outstanding physical properties. The process is shown to be applicable to a wide variety of high performance materials. Additionally, significant improvements in green strength and ejection forces
are realized. (1994)
(472 kb)
Properties of High Density Ferrous PM Materials a Study of Various Processes
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Several methods of achieving higher density in ferrous P/M parts are possible. Double press/double sinter allows densities in excess of 7.3 g/cm3 but is limited by cost and geometry considerations. A new method of single processing high performance materials is evaluated and compared to other methods of processing. The comparison is performed utilizing Ancorsteel 85HP and Distaloy 4800A base materials. Various green and sintered properties are evaluated including; green strength, transverse rupture strength, tensile properties and impact values. The data clearly demonstrates that the patented (1) ANCORDENSE™* process offers performance comparable to double press/double sinter processing. Green density values of approximately 98.5% of the pore free density limit are achieved with a single compaction step. (1994)
(520 kb)
Properties of Heat Treated PM Alloy Steels
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Further development of ferrous P/M technology into highly stressed applications will require the development of P/M steels with mechanical properties approaching those of cast or wrought products. The P/M process offers many routes to improve mechanical properties through alloy design, increased density and high temperature sintering. The paper will present the results of a study into the effects of density and composition upon the microstructure and properties of quenched and tempered P/M alloy steels. (1993)
(2.18 mb)
Fusion Welding PM Components for Automotive Applications
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The paper identifies welding methods that are most often used to join P/M automotive components. Various weld procedures associated with the different methods are discussed. Examples are presented along with appropriate process information. A more detailed application development involves Gas Tungsten Arc
welding a stainless P/M exhaust bushing to a wrought stainless steel tube. (1993)
(431 kb)
Dust and Segregation-Free Powders for Flexible PM Processing
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During the past few years, there has been increasing demand placed on P/M parts
producers to improve density uniformity, weight variation, alloy homogeneity and
dimensional control. Enhanced flow and die fill characteristics are also required to
improve productivity and reduce the percentage of green scrap. The ANCORBOND® process developed by Hoeganaes has satisfied many of these requirements by bonding the alloy additives and fines to the base iron particles. Increased concerns regarding the inability to retrofit higher apparent density premixes to existing tool sets, a slight loss of compressibility and the desire to reduce the total organic content for improved burnout response led to further improvements in the bonding process. Several factors that contribute to the performance and greater flexibility of binder-treated mixes compared with regular mixes will be discussed in this paper. (1993)
(298 kb)
Effects of Powder Properties and Processing On Soft Magnetic Performance of 400-Series Stainless Steel Parts
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With the advent of growth in soft magnetic applications suitable to Powder Metallurgy, powder manufacturers parts fabricators and end users of such parts must gain a better understanding of the relationships between powders, processing and the ultimate performance of soft magnetic P/M parts. Studies have been conducted and valuable data extracted on the subjects of pure iron, iron-phosphorus, iron-silicon and prealloyed iron-nickel alloys as they relate to magnetic properties. With the identification of applications requiring corrosion resistance as well as mechanical and magnetic properties, including the Anti-lock Brake System (ABS) tone wheel, industry is investigating ferritic stainless steel solutions. This study represents an effort to provide some initial answers to questions regarding the "real world" capability of P/M production of high quality, ferritic stainless steel parts that exhibit excellent magnetic properties. (1993)
(699 kb)
Surface-Hardenable Heat Treated PM Steels
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The addition of fine particles (< 20μm) of high-carbon ferroalloys to the high compressible prealloy powders, Ancorsteel® 85 HP and Ancorsteel 150 HP, has been shown to be a practical way of producing ferrous low-alloy steels containing
chromium and manganese. Increased sintering temperatures improved the mechanical
properties of the materials and the effect was particularly noticeable at 2350°F.
The ferroalloy additions significantly enhanced the hardenability of the base low-alloys. Materials based on the low-alloy powder containing 1.5% molybdenum were more hardenable than those based on the 0.85% molybdenum alloy. These materials are well suited for plasma nitriding and should find use in gears and cams that require a hard wear-resistant surface coupled with a strong, tough core. (1992)
(1.17 mb)
Effects of Processing and Materials On Soft Magnetic Performance of Powder Metallurgy Parts
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Soft magnetic properties of P/M parts are influenced by materials and processing. This paper will review the magnetic properties of several iron-based materials along with how various processing steps influence magnetic properties. In particular, density, sintering temperature, sintering time and sintering atmosphere effects will be examined. Special attention will be paid to the influence that sintering conditions have on chemistry and the resulting effects on magnetic properties. Materials investigated in the study include pure iron and combinations of iron, phosphorus, silicon and nickel. (1992)
(400 kb)
Sinter Hardening Low-Alloy Steels
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The availability of prealloyed steel powders employing molybdenum as the major alloying element offers new levels of compressibility and mechanical properties.
When the prealloyed powders are combined with conventional P/M additives such as copper, nickel and graphite, it is possible to develop high strength martensitic microstructures directly from the sintering cycle. The impact and tensile properties of copper, nickel, graphite premixes based upon the prealloyed molybdenum steels are compared under controlled cooled conditions. The ability to balance tensile strength, toughness and hardness by control of alloy chemistry is illustrated. (1992)
(897 kb)
High Performance Ferrous PM Materials Utilizing High Temperature Sintering
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Several new and more challenging P/M applications require materials that exhibit higher strength along with improved dynamic property characteristics. To meet these requirements, development efforts focused on material grades capable of achieving high performance properties when sintered at elevated temperature. Several elements, specifically nickel and copper, were admixed to the water atomized, prealloyed low-alloy steel powders Ancorsteel® 85 HP and 150 HP using the patented ANCORBOND® process. Tensile and impact performance of the resulting materials have been reviewed along with quantitative metallography of selected as-sintered samples. The results indicate the type and amount of each admixed element plays an important role in achieving specific characteristics. In addition, the overall performance values are greater for the single press and sinter technique used in this investigation than could previously be achieved using a double press - double sinter process. (1992)
(951 kb)
High Performance Ferrous PM Materials for Automotive Applications
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The majority of automotive components (transmission, chassis, suspension, and engine) for which parts with densities up to about 7.0 g/cm3 are suitable have already been converted to P/M and there are few opportunities for growth in this
density range. In order to meet the requirements of more demanding applications there has been a trend toward higher densities through the use of infiltration, double pressing/double sintering, or powder forging (l - 4) to produce parts such as synchronizer hubs, crankshaft sprockets, chain sprockets, gerotors, steering column tilt levers, planetary gear carriers, parking gears shift levers, and connecting rods. While powder forging has been shown capable of producing parts, which are superior to wrought, or cast products process economics have limited market penetration by this technology (5). The double press and sinter route also adds process costs and is probably too expensive for other than premium applications. There is a real need for a systems approach that will permit double pressed and sintered or infiltrated performance characteristics to be achieved by means of single compaction processing. The mechanical properties of P/M materials are directly related to their microstructure and the size, distribution, and morphology of the porosity they contain. Alloying additions are made to develop specific material performance
characteristics. However, the manner in which the alloys are constituted has a significant effect on the porosity and microstructure of the final product (6). (1991)
(793 kb)
PM Joining Processes, Materials and Techniques
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This paper discusses the different types of joining processes most often used in conjunction with ferrous P/M material grades and components. Information from previous publications and a literature review on the various processes are highlighted. Useful design information and processing techniques are listed along with identifying the weldability of various P/M material compositions. (1991)
(517 kb)
Improved Dimensional Control and Elimination of Heat Treatment for Automotive Parts
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The automotive industry has expressed concern about the general quality of heat treatment (austenization and quenching) and the desire to reduce or eliminate dependence upon this process whenever possible. Therefore, in a continuing effort for improvement during the past year, a process has been developed that eliminates the conventional heat treating operation for some applications. Some of these finished parts require both a high impact strength and a hardened wear resistant surface. The Charpy impact, tensile and TRS properties of a binder treated premix based on a partially alloyed powder have been evaluated utilizing a variety of processing conditions. These include various carbon contents, sintering temperatures and sintering times. Quantitative metallography was used to evaluate the pore size, pore shape and microstructural constituents present as a result of the various materials and processes. These factors were then correlated with the measured properties. (1991)
(627 kb)
Performance Characteristics of a New Sinter Hardening Low Alloy Steel
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A martensitic microstructure can be developed in some powder metallurgy materials without the need for a secondary heat treatment operation provided the material is cooled sufficiently rapidly from the sintering temperature. These P/M materials are termed "sinter-hardening" steels. The partially alloyed powder, Distaloy 4800A, and nickel-molybdenum prealloyed steels such as Ancorsteel ® 4600V with copper additions are capable of being sinter-hardened. Ancorsteel 85 HP, a new highly compressible low-alloy powder employing molybdenum as the primary alloying element, is also capable of being sintered-hardened when copper and graphite additions are made to it. Ancorsteel 85 HP has a higher compressibility than nickel-molybdenum prealloyed powders. The effect of cooling rate has been studied on the microstructure and mechanical properties of Ancorsteel 85 HP + 2% copper + 0.9% graphite. Tensile and impact properties have been evaluated for a range of material densities and compared with those obtained with samples based on Ancorsteel 4600V. (1991)
(656 kb)
Ferrous Powders - How Alloying Method Influences Sintering
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The mechanical properties of P/M materials are directly related to their microstructure and the size, distribution, and morphology of the porosity they contain. Alloying additions are made to develop specific material performance characteristics. However, the manner in which the alloys are constituted has a significant effect on the porosity and microstructure of the final sintered product (1,2). (1991)
(1.63 mb)
Tensile, Impact and Fatigue Performance of a New Water Atomized Low-Alloy Powder - Ancorsteel 85 HP
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A new water atomized, prealloyed powder has been developed containing 0.85% molybdenum as the alloying addition. The as-sintered and heat treated tensile, impact and fatigue performance have been determined for a range of graphite additions using both single and double pressing techniques. Results indicate that the new powder, Ancorsteel 85 HP, has a unique ability to be compacted and repressed to densities not attainable with existing prealloyed nickel-molybdenum powders. The higher densities achieved produce performance equivalent to or better than Ancorstee12000 or Ancorstee14600V using conventional single compaction techniques. However, the additional density increment achieved during repressing results in mechanical properties in excess of what is possible with the existing low-alloy steels. (1990)
(1.18 mb)
Steering Column Tilt Lever - PM Material Development
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Automotive steering columns use a variety of levers to lock the flit mechanism in position. A new P/M material has been developed to withstand the impact and hardness performance requirements of this application. The new material is currently subjected to a brief surface carburizing and tempering treatment to impart wear resistance. The P/M part only requires honing of the pivot hole to meet the specified tolerance. Long term plans are to achieve the desired performance requirements using a modified version of the new P/M material, with a higher graphite addition, which can be used after tempering the" as-sintered" product. (1990)
(1.14 mb)
Properties of Parts Made from ANCORBOND Processed Carbon-Nickel-Steel Powder Mix (FN-0208)
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Studies were conducted to determine the effects on property variability of parts made from a bonded Ancorsteel 1000 mix containing 0.95% graphite, 2.0% nickel, 0.6% Acrawax and 0.3% zinc stearate. The part geometry studied was that of a cylindrical bushing. The treatment effects on powder properties and on several parts properties were determined. The powder properties included the traditional green and sintered properties and the graphite and nickel dusting resistance’s. The parts properties surveyed included both green and sintered properties and sintered carbon and nickel contents. Similar studies of a companion regular mix of nominally the same composition were conducted for purposes of comparison. (1989)
(273 kb)
A Review of Nondestructive Testing Methods and Their Applicability to Powder Metallurgy Processing
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The problem of forming defects in green parts during compaction and ejection has become more prevalent as parts producers have started to use higher compaction pressures in an effort to achieve high density, high performance P/M steels. In this review, several nondestructive inspection methods are evaluated, with the aim of identifying those, which are practical for detecting defects as early in the production sequence as possible. The most promising NDT methods for P/M applications include electrical resistivity testing, eddy current and magnetic bridge testing, magnetic particle inspection, ultrasonic testing, X-ray radiography, gas permeability testing, and gamma ray density determination. The capabilities and limitations of each of the techniques are evaluated in this review. (1988)
(1.24 mb)
Fatigue Properties of PM Materials
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The tensile properties and fatigue endurance limits of several widely used P/M steels have been tested. Statistical estimates of the 99.9% survival stress have shown that fatigue endurance ratios can vary from 0.16 to 0.47. Thus the use of 0.38 as a rule of thumb for estimating the fatigue endurance limit from static tensile property data can result in large errors. (1988)
(2.30 mb)
Microcleanlinesss Studies of Low Alloy and Carbon Steel, Powders Intended For Powder Forging Applications
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The results of ten years of experience aimed at continuously improving the quality of powders for forging applications are reviewed. An automated image analysis procedure for inclusion assessment is described which evaluates the inclusion content of samples and defines fragmented inclusion clusters on the basis of a concept of near neighbor separation. A task group approach was used for cause-and-effect analysis to determine the source of different inclusion types and eliminate and/or reduce their incidence. The benefits of this approach are demonstrated by the significant reduction effected in inclusion levels. (1988)
(803 kb)
STATISTICAL PROCESS CONTROL IN IRON PONDER PRODUCTION AND NEW PRODUCT DEVELOPMENT
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SPC is discussed with a view to indicating its implications not only to manufacturing and quality but to research and product development as well. In the manufacturing/quality area, the efforts and methods attending full-scale implementation of SPC are briefly reviewed with special reference to the differences inherent in powder making versus manufacturing of parts. SPC charting techniques suitable for powder making are described and discussed. (1988)
(245 kb)
Impact and Fatigue Characterization of Selected Ferrous P/M Materials
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Dynamic property data on pressed and sintered ferrous powder metallurgy materials have come under increasing demand as the P/M industry has grown into areas of application involving more highly stressed components. Data collected from relatively simple dynamic property tests will provide new avenues for P/M alloy development. (1987)
(922 kb)
Properties of Parts Made From a Binder Treated 0.45 Phosphorus Containing Iron Powder Blend
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Studies were conducted to determine the effects on property variability of parts made from a binder treated blend. The blend was a lubricated admixture of Fe3P and Ancorsteel 1000B iron powders. The parts were cylindrical bushings having a nominal wall thickness of 0.25 inches and otherwise measuring 1.5 inches in outside diameter and 2.0 inches in height. In conducting the study, an analysis of variance design was employed to enable assessment of the relative contributions of six variance sources as follows: 1) testing; 2) microsegretation; 3) part to part for pairs pressed back to back and sintered side by side; 4) sintering within trays; 5) sintering tray to tray, and 6) macrosegregation. (1987)
(164 kb)
High Performance Ferrous PM Materials - The Effect of Alloying Method on Dynamic Properties
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A comparison has been made between fully prealloyed, partially prealloyed, and elementally admixed alloys in the "as sintered" condition in order to assess the influence of microstructural and chemical homogeneity on the tensile, impact, and fatigue properties. Elementally admixed and completely prealloyed powders were prepared with chemistry similar to that of the diffusion bonded Distaloy 4600A (nominally 1.8 wt. % Ni, 1.6 wt. % Cu, and 0.55 wt. % Ho). An addition of 0.6% graphite was made to each of these materials. (1986)
(918 kb)