CREEP DEFORMATION OF STAINLESS STEEL AT LIQUID NITROGEN TEMPERATURE

摘要

Creep deformation of stainless steel SUS 304 is experimentally investigated at liquid nitrogen temperature. The loading tests are conducted by subjecting thin-walled tubular specimens to combined axial load and torsion in liquid nitrogen. Creep behavior is examined at different stress levels of tensile, compressive and torsional loads. Tensile creep deformation is more significant than torsional and compressive creep deformations. Creep strain has the hardening effect on plastic deformation and the effect is almost same as plastic strain. The creep deformation is related with the plastic hardening rate of stress-strain curves. Small plastic hardening rate results in large creep deformation and large plastic hardening rate results in small creep deformation. The creep deformation also depends on the directions of combined loading. With changing the direction from combined torsion and tension to combined torsion and compression, the creep strain decreases gradually. Compressive creep strain is the smallest for the same combined stress level.