The new iron base powders for advanced automotive PM applications

The reasons for the industrial development of P/M parts are briefly reviewed. The progressive strength increases of sintered steels supported the growth of high stress applications. The biggest growth has been observed in the automotive industry. The influences of different alloy additions on processing are surveyed, together with the alloying methods that can be used in P/M. The need for specific test and assessment criteria for high property P/M steels is set out. In sintered steels a controlled and repeatable lack of homogeneity enhances the mechanical strength, with special respect to fatigue and impact. The introduction of diffusion-bonded materials, which began the second half of the Sixties, represented a dramatic break-through in the availability of high -strength sintered steels. The appearance of these new powder grades strongly contributed to the increase in P/M part production for car industry. More recently Mo prealloyed grades widened the range of high performance powder grades. Among different alloy additions, molybdenum represents the best combination of suitability to pressing and sintering, while its positive influence on hardenability is excellent. For about 15 years, Distaloy powders have been produced using a plain iron powder as a base. Recently, new grades have been introduced, which are based on an Fe -Mo alloy. The new grades have been purposely formulated considering previous experience and the increasing demands of exacting P/M part users.