PM structural parts move to higher density and performance

Abstract

The automotive market is particularly important for PM (ferrous) structural parts. Growth in this market initially relied on developments in shape complexity and size of PM products, but, more recently, achieving higher performance has been identified as an important means of maintaining growth. Achieving higher density levels has also emerged as a prime means of increasing performance of PM structural parts. The industry's original attack on this objective, powder forging, is considered and the successes and limitations of the process defined. More recent process and/or material developments, that are closer variants on the basic press/sinter PM technology, are then described. These comprise three possible approaches: increasing green density; densification during sintering; and an additional post-sintering densification step, often applied locally rather than throughout the part. In each case, detailed developments are described and important product application types highlighted. Finally, the market penetration already secured into higher performance automotive applications is considered and a personal view provided on which issues might control the pace of future market penetration.