OS1305 ECAP加工したSUS316Lステンレス鋼の引張変形の温度依存性

Abstract

Tensile deformation property of the SUS316L stainless steel containing nanostructured twins was investigated at various temperatures. By the equal channel angular pressing (ECAP) at 43K, the nanostructured twins with average thickness of 50nm could be generated in the SUS316L steel. In the present study, the SUS316L steels processed by the ECAP for one pass and three passes were prepared. The tensile tests on the ECAPed SUS316L steels shaped to strip specimens were conducted at temperatures ranging from 77K to 673K. Ultimate tensile strength of the 3-pass, 1-pass and as-prepared specimens at 673K were 976MPa, 839MPa and 435MPa, while those at room temperature were 1200,900, and, 560 MPa. As well as the as-prepared specimen, the tensile strength of the 1-pass specimen was almost unchanged even at 673K. This thermal stability can be attributed to high-density twin boundaries which certainly have stable interface atomic arrangement. At tensile deformation tests below room temperature, the tensile strength increased with decreasing temperature for all the specimens. It should be noted that ductility of the 1-pass specimen was significantly improved, compared with the ductility at room temperature. The enhanced strength and ductility at the low temperature should be associated with strain-induced martensitic transformation.