Subzero-加工せる18-8系不銹鋼について（第1報）

抄録

The influence of subzero-working on the properties of austenititc nickel-chromium stainless steel was studied using steel containing 0.08% C, 0.89% Si, 2.00% Mn, 10.26% Ni, 18.11% Cr and 1.52% Mo. The specimens were cold-worked to several degrees by means of statical compression at the temperatures of 20°, −72°, and −183°. With the lowered temperature of working, the plasticity of the steel was reduced, being work-hardend markedly. It was found magnetically that no martensite was formed by working at 20°, while by subzero-temperature working it was formed in amounts increasing with the drop of temperature as well as the increased degrees of working. The Ms point of the steel must be under −183° if it exists, and the Md point lies at +20°∼−72°. The process of changes by tempering the worked steels upon reheating was also pursued by means of hardness, dilatometric and magnetic measurements. During continuous heating, the preformed martensite by the subzero-working was found to begin to transform into austenite at about 440° and to finish the change at about 640°, while the recovery and the recrystallization of the deformed austenitic structure, which remained untransformed by the working, proceed gradually from about 630° and continue up to nearly 900°.