Dynamic mechanical properties of stainless steel 0Cr18Ni10Ti welded joint at elevated temperatures and high strain rates

Dynamic mechanical behaviors of base and weld materials for the reactor engineering pipeline material, 0Cr18Ni10Ti, are studied at elevated temperatures and high strain rates with split Hopkinson pressure bar (SHPB), which is installed with heating and synchro assembly system. The tests are carried out at loading rates ranging from 200 to 3800 s^-1 and temperatures ranging from 25 to 600°C, and different stress-strain curves are obtained correspondingly for each condition. Emphasis is put on the study of strain rate and temperature sensitivity of plastic flow stress, and the Johson-Cook (J-C) models are obtained for both the materials. The results show that the base and the weld materials both have evident heat softening effect and strain hardening effect, but the effect of strain rate hardening is comparatively weaker. Meanwhile, these effects are also effected by temperature, and the hardening effects induced by strain and strain rate are weakened at higher temperature. With the increase of strain, the flow stress of both the materials even begin to decrease at a certain deformation. The intrinsic mechanism is discussed according to the thermally activated dislocation motion theory. Optical microstructures of the materials are also observed and analyzed.