Densification of Stainless Steel Powder Compacts During Sintering

Abstract

Densification characteristics of stainless steel compacts having various compositions in α, γ and γ+ε phases were examined by dilatometry. Results obtained are summerized as follows:1) The linear shrinkage (ΔL/L0) at the initial stage of the isothermal densification is given as a function of porosity (ε), particle size (r) and sintering time (t):ΔL/L0≅K0-m⋅(ε/ε0)⋅tn, where ε0 is the maximum porosity, and K0 a constant, m and n depend on the phase during sintering, e.g. m=1.5, n=0.5 in α and γ+δ phase region, and m=1.2, n=0.4 in γ phase.2) Activation energy for α phase of 410L was 53, 500 cal/mol, and for γ phase of 347, 53, 600 cal/mol and 96, 000 cal/mol below and above 1300°C respectively.3) Sintering of austenitic stainless steel powder is promoted by the presence of δ-phase in γ matrix. Activation energy calculated from the dimensional change was 70, 600-76, 500 cal/mol.