Abstract
The high strain powder metallurgy (HS-PM) process was applied to an SUS316L gas atomized powder by 360ks mechanical milling (MM) with a planetary ball mill under an Ar atmosphere. The MM powder was annealed at 1073 K, 1173 K, 1273 K. Each structure was investigated using XRD and TEM/EDS. It was confirmed that as-MM powder consisted of an ultra fine (α+γ) microduplex structure. It was supposed that the a phase was formed as the HS-PM process by increasing free energy of the austenitic phase. Fine grain structure with its grain size of 2.3μm composed of fine carbides and γ phase was obtained when MM powder was annealed at 1073 K for 3.6 ks. It was also confirmed that these fine carbides restrain the grain growth. But at 1173 K and 1273 K, the fine carbides were not seen, so that grain size increased drastically.
