Phosphorus Irons

Phosphorous Irons Technical Publications

196. Sintering of Powder Premixes - A Brief Overview Advances in the understanding of the sintering of powder premixes have contributed significantly to the growth of the ferrous powder metallurgy industry. This includes sintering both in the solid state and in the presence of a liquid phase. In this article, the sintering of iron powder premixes containing: 1) graphite; 2) nickel and graphite; 3) copper and graphite; 4) Phosphorus as ferrophosphorus; and, 5) boron as ferroboron are discussed. The evolution of microstructure and mechanical properties are discussed as well.

150. The Effect of Processing and Density on PM Soft Magnetic Properties With the trend towards more widespread use of automotive electric systems such as electric power steering, new opportunities exist for P/M soft magnetic alloys. These applications require high density for magnetic properties and precision. To meet density, precision and geometry complexity requirements, secondary operations are usually employed, which degrade magnetic properties. Annealing can be utilized for recovery of the magnetic properties, but with the potential for dimensional changes. Through the use of an advanced binder system, higher densities with subsequent increases in magnetic properties can be achieved in a single compaction step. The influence of secondary operations, processing methods such as the use of an advanced binder system and annealing are presented for Fe, Fe-P and Fe-Ni materials.

130. Effect of Processing and Materials Selection on P/M Part Magnetic Properties The increased usage of electromagnetic components in the drive train of cars and SUV’s often impose conflicting requirements of good magnetic properties with high strength and high hardness. Traditionally, P/M soft magnetic materials utilizing iron-phosphorus alloys are characterized by good magnetic performance but relatively low strength, hardness. Thus to achieve the mechanical property and dimensional requirements it is often necessary to perform secondary operations such as sizing, coining, or machining often in combination with a separate heat treatment operation. This paper will focus on the effects of various secondary operations on the mechanical and magnetic properties of soft magnetic materials in an actual component. Additionally, data will be presented on a higher strength magnetic material and the potential for this material to replace existing soft magnetic materials and possibly eliminate some of the secondary operations intended to increase the strength of the actual component.

118. Processing of Ferro-Phos-Containing Mixes in Low Hydrogen Atmospheres Ferrophosphorus-containing premixes with iron are used extensively in magnetic applications. Recent trends toward reducing cost necessitate reduction of hydrogen content in the sintering atmosphere. This reduction of hydrogen leads to occasional brittle fracture in parts made from ferrophosphorus mixes. The objective of this investigation is to develop a robust powder that could be used in low hydrogen-containing sintering atmosphere. A design of experiments was developed to include residual elements and oxygen level in the ferrophosphorus powder. The results suggest controlling the oxygen in the ferrophosphorus is critical in achieving high impact energies while sintering in low hydrogen atmospheres. Addition of a minute amount of graphite can improve the impact strength of the otherwise low impact material.

100. Higher Green Strength Enhancements to Increase Process Robustness The use of binder-treated premixes has grown dramatically since the introduction of the technology in the late 1980’s. Decreased levels of respirable dust coupled with reduced segregation and significantly improved powder flow have helped to stimulate this growth. More recently, binder-treated premixes that significantly enhance the green strength of P/M parts have been developed. The higher green strength results in more robust handling of green parts prior to the sintering operation and reduced levels of green scrap. In addition, the significantly higher green strength provides an opportunity for “green” machining of the P/M parts prior to sintering. This paper will discuss recent advances in binder-treatment technology and will review production experience with binder-treated premixes.

96. P/M High Strength Magnetic Alloys Sintered P/M magnetic materials are characterized by good DC magnetic performance with relatively low yield and tensile strengths, typically the tensile strengths are less than 50,000 psi. This inherently low strength of the common magnetic alloys results from the use of pure iron or iron phosphorus alloys. This low strength often limits the potential applications for sintered P/M magnetic materials. Described in this paper are P/M alloys that have tensile strengths approaching 70,000 psi (480 MPa) in the as sintered condition with tensile ductility approaching 10% and having magnetic properties equal to the pure iron and / or iron phosphorus alloys. These alloys are intended for higher strength, magnetic applications. A comparison to the standard P/M magnetic alloys will be made.

95. Conventional Powder Metal Is Still A Technology Leader Recent advancements in powder metal technology have made it possible to achieve physical properties rivaling many competitive technologies. Improvements in raw materials have made powder metal a viable replacement for several malleable and ductile cast irons. The combination of raw material and processing improvements continues to push powder metal technology performance into the wrought steel arena. Nevertheless, in the midst of all of these technological advancements, conventional powder metallurgy is still providing innovation in torque transfer systems. At BorgWarner’s TorqTransfer Systems division, conventional powder metallurgy has found application in six separate components of the newly created interactive torque management system dubbed ITM. This patented torque transfer device provides the all-wheel drive technology for MotorTrends SUV of the year – the Honda Acura MDX.[4] This paper describes how conventional powder metal technology provided the perfect solution for this highly innovative torque transfer technology.

87. Advances in Binder-Treatment Technology The use of binder-treated premixes has grown dramatically since the introduction of the technology in the late 1980’s. Decreased levels of respirable dust coupled with reduced amounts of alloy addition segregation and significantly improved powder flow have helped to stimulate this growth. More recently, binder-treated premixes have been developed that significantly enhance the green strength of P/M parts. The higher green strength results in more robust green parts for handling prior to the sintering operation and reduced levels of green scrap. In addition, the significantly higher green strength provides the opportunity for “green” machining of the P/M parts prior to sintering. This paper will discuss recent advances in binder-treatment technology and will review production experience with binder-treated premixes.

72. Advances in Binder - Treatment Technology Statistical Data on ANCORBOND Plus 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.

48. A Performance Comparison of Various P/M Lubricants and Routes to Improvement 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.

47. The Manufacture of Electromagnetic Components by the Powder Metallurgy Process 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.

42. The Effect of Microstructure on Fatigue Properties of High Density Ferrous Materials 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.

41. Properties of Several ANCORDENSE Processed High Performance Materials 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.

36. Powder Metallurgy in Electromagnetic Applications New product and process advances have expanded the potential for powder metallurgy growth into a variety of new applications. The ANCORDENSE™ process has enabled high density powder metallurgy parts to be attained cost effectively. Increases in density improve the magnetic performance of powder mettallurgy materials. In addition, a new process for producing iron powder with a then thermoplastic coating has been developed. Compacts produced from this material exhibit excellent high frequency magnetic properties. The role that these advances in powder metallurgy play in electromegnetic applications is discussed.

27. Recent Developments in Ferrous Powder Metallurgy Alloys 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.

23. High Density Processing of High Performance Ferrous Materials 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.

19. Effects of Processing and Materials on the Soft Magnetic Performance of Powder Metallurgy Parts 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.

3. Fatigue Properties of P/M Materials 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. The single most effective method of improving fatigue properties is to increase the part density. Fractographic observations were made on some of the fatigue failures, including stable and unstable crack growth.

2. Properties of Parts Made from a Binder Treated 0.45% Phosphorus Containing Iron Powder Blend 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.

Relative to parts made from a companion control blend, the results of the study showed that the binder treatment was effective in reducing variability in each of the following properties: dimensional change, crush strength, hardness and average phosphorus content. The Analysis of Variance results suggested that the observed reductions were due primarily to reductions in sintering was also indicated to be a significant variance source, although in this case, it also appeared to be affected by the presence of microsegregatlon.

The findings are assessed and discussed both in traditional statistical terms and in terms of Statistical Process Control. The latter terms are employed to show how the variability reductions may be translated into quality and/or economic benefits in actual parts making situations.

1. Impact and Fatigue Characterization of Selected Ferrous P/M Materials 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. Un-notched Gharpy impact energy and rotating bending fatigue tests have been used to characterize commonly used P/M steels. The endurance ratios of porous steels have been found to be relatively insensitive to processing, with higher strength materials giving proportionally higher endurance limits. Since impact energy was not strongly affected by varying the carbon content up to the eutectoid composition, increasing the carbon content of low alloy steels is a viable way of increasing endurance limit. Impact energy transition temperature has been found to be a factor in carbon-free phosphorus steels, but not in conventional low alloy steels. As has been indicated in the literature, sintered density is crucial to both impact energy and fatigue endurance limit. Metallographic examination of the fatigue cracks has provided some insight into the nature of the R.B.F. test.

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