AISI 400 series stainless steels are widely used in MIM today with the 420 grade particularly popular for structural applications. Low carbon grades offer a valuable combination good corrosion resistance coupled with soft magnetic characteristics such that 430L grade is a popular choice for the fabrication of sensors and motor armatures.
It is understood that both sintering conditions and post processing can affect the final hardness, corrosion resistance and magnetic performance of MIM parts. In this study, we examine the influence of raw materials and process variables on the sintered density, hardening response and corrosion performance of 430L parts. The behaviour of 430L made by both a prealloy and master alloy route is examined and the effect of niobium additions, known to be an effective stabilizing element, is also investigated. We relate MIM part properties, both in the as-sintered and heat treated condition, to final part chemistry and microstructure.