Powder Forging

Powder Forging Technical Publications

169. Rolling Contact Fatigue Performance Contrasting Surface Densified, Powder Forged, and Wrought Material Previous experimental work demonstrated that rolling contact fatigue durability of high-density powder metallurgy samples was influenced by depth of surface densification (achieved via roll densification), sintering temperature, and heat treat practice. One observation of the previous work was reduced rolling contact fatigue life at high Hertz stress levels relative to wrought machined steel samples. There were also some questions regards the influence of nickel rich regions and how they affected rolling contact fatigue performance. In an effort to understand the influence of elemental nickel additions, FLN2-4405 samples were sintered at 2050 °F (1120 °C) and 2300 °F (1260 °C) and subsequently powder forged to full density. This experimental work was designed to clarify the effects of elemental nickel additions on rolling contact fatigue durability. Additionally, wrought AISI 8620 carburizing steel was machined into rolling contact fatigue samples, carburized and tested. Additionally, the AISI 8620 was evaluated for tensile, impact and fatigue characteristics in the quench and tempered condition.

164. Full Density Properties of Low Alloy Steels Full density produces the best mechanical properties in a P/M or P/F component. Full density properties are available for traditional P/F materials, which are based on unalloyed base iron or low alloys with Ni and Mo additions. Additional base alloys have been developed which may be suitable for full density processing. This paper outlines the full density properties of these steels. Mechanical properties and microstructure will be presented.

37. Powder Forging Following a brief history of powder forging, the process is defined and an explanation provided of the difference between re-press and upset forging. Material requirements are reviewed, material designations defined, and particular emphasis is placed on the need for low levels of nonmetallic inclusions along with minimizing cross-product contamination in P/F materials. Process considerations are discussed and the influence of process variables on the level of residual porosity on the mechanical properties of P/F materials is illustrated and typical properties of powder forged materials summarized. Test methods and procedures for the quality assurance of P/F parts are then covered in detail prior to reviewing some examples of powder forged parts. Powder forged connecting rods have been responsible for most of the growth in powder forging in recent years. A brief history of P/F connecting rod production is given along with a discussion of recent developments.

30. Continuous Improvements in Atomized Powders Through Team Oriented Problem Solving 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.

8. Powder Forging is a process in which unsintered, presintered, or sintered powder metal preforms are hot formed in confined dies. The process is sometimes called P/M (powder metallurgy) forging, P/M hot forming, or is simply referred to by the acronym P/F. When the preform has been sintered, the process is often referred to as "sinter forging."

6. Microcleanliness Studies of Low Alloy and Carbon Steel Powders Intended for Powder Forging Applications 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.

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