Tensile Properties of Extrusion Consolidated Type 304 SS Rapidly Solidified Powders

摘要

Rapidly solidified Type 304 SS powders prepared by centrifugal atomization (CA) using helium as a quench gas and having a dendritic microstructure were hot extruded, resulting in fully consolidated bars with a recrystallized fine grain size. The extruded bar, as well as the powder, contained 8 appM of entrapped helium acquired during powder processing. Prior to tensile testing, the specimens were given various preconditioning heat treatments (PCHTs). The tests were conducted in air over a temperature range of 24 to 800 sup 0 C at a strain rate of approximately 10 sup -4 /s. The tensile properties of the CA 304 SS extruded powders were compared to an ingot metallurgy (I/M) Type 304 SS material with a similar chemistry. The tensile strengths and reductions in area were superior for the powders, compared to the I/M material, but uniform and total elongations were slightly lower. There were no obvious helium influences associated with the ductilities, e.g., embrittlement. The preconditioning heat treatments for the powder specimens had a significant influence on the strength properties. Strengthening mechanisms are discussed, including grain size, entrapped helium influences and apparent carbide effects. 6 refs., 14 figs., 1 tab. (ERA citation 13:003693)