Some Factors Influencing the Sintering Behaviour of Austenitic Stainless Steel Powders

Abstract

Densification studies of sintered stainless steel powder blends have shown that the introduction of delta-ferrite into the micro structure increases substantially the sintering rate of the compact. Model experiments, in which spherical particles of a 316 powder were sintered on several different base plates including iron, 18Cr–12Ni stainless steel, iron–12% nickel, have been carried out to provide more detailed information. Quantitative observations have been made on the rate of neck growth and on the compositional gradients which develop between particle and plate. It has been found that the sintering rates were very sensitive to the composition of the base plate and to the presence of austenite/ferrite interfaces. Micro-examination and the use of electron probe microanalysis indicate that interdiffusion of elements between particles and plates is by both surface and volume diffusion.