Processing and Properties of AISI 420 MIM Parts Manufactured via Prealloy and Master Alloy Routes

摘要

AISI 420, a hardenable martensitic stainless steel, offers an attractive combination of high hardness and wear resistance coupled with moderate corrosion resistance. These characteristics mean that the alloy is a popular choice for a wide range of MIM applications including automotive components, power tools and surgical instruments. It is, however, a difficult material to process successfully via MIM as the sintering process must be controlled over a relatively narrow temperature range in order to achieve adequate and consistent properties. In this study, we compare the processing and properties of AISI 420 parts made using gas atomised prealloy powders over a range of particle sizes as well as parts made using a 4x concentration master alloy blended with carbonyl iron powder. The differences in densification behaviour are evaluated for each raw material mix over a range of sintering temperatures. Microstructure - property relationships are presented with respect to tensile properties and hardness in both the as sintered and heat treated conditions.