Creep densification behavior of micro and nano metal powder: Grain size-dependent model

The effect of grain or powder particle size on densification and deformation of solid and porous stainless steel was investigated during creep deformation at various elevated temperatures. The power-law creep strain rate with grain size-dependent parameters was calculated from various experimental data whose powder particle size ranged from nano- to microscale. New grain size-dependent parameters were introduced into the constitutive model of Abouaf et al. [Abouaf M, Chenot JL, Raisson G, Bauduin P. Int J Num Mech Eng 1988;25:191] and the density functions of Fa and Fb were developed as a new form considering those new grain size-dependent parameters. The modified model with grain size-dependent parameters was implemented in a finite element program. The finite element results were compared with experimental data for densification and deformation of stainless steel powder during hot isostatic pressing, hot pressing, and sinter forging.