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Powder Metallurgy (P/M) is an increasingly viable alternative for applications requiring high material performance. Continuous advances in alloy systems and processing techniques, combined with powder metallurgy's ability to produce complex net shapes, have made it possible for powder metallurgy to compete with other technologies in engine and transmission applications. This paper will focus on new alloy systems and advanced processing techniques. The properties achievable with currently available materials, such as chromium containing materials, combined with advanced processing techniques, such as warm compaction and surface densification, will be presented. Additionally, a case study where a warm compacted synchronizing latch cone in a heavy duty truck transmission was found to have equal or superior performance to precision forged and powder forged latch cones.

The past decades have seen a continuous growth of the use of PM parts in automotive applications. However, the performance requirements the components must meet are more and more demanding. Transmission gears for automotive applications are complex in shape and require both very high geometrical accuracy in terms of gear quality and very high mechanical performance in terms of durability of tooth flank and root. Powder metallurgy is very cost effective for complex shaped parts and by adding a selective densification of the teeth the accuracy and mechanical performance requirements can be met at a very low added cost. In this paper a process route consisting of compaction, sintering, surface densification by rolling and finally heat treatment have been studied to assess the feasibility of producing transmission gears by powder metallurgy. Helical and spur gears were used in the study where the densification as well as the resulting gear quality and durability were tested.