Effect of Pre-strain on Cyclic Loading of Stainless Steel SUS 304 at Low Temperature in Liquid Nitrogen

Cyclic plastic deformation subsequent to pre-strain of SUS 304 stainless steel is experimentally investigated at low temperature in liquid nitrogen under torsional, tensile and compressive loading conditions. Thin-walled tubular specimens given pre-strain were subjected to cyclic loading under stress-controlled conditions. The pre-strain is conducted at 77 K, and subsequent cyclic lading under constant strain amplitude is given at 77 K. The cyclic stress-strain curves are saturated by increasing number of cyclic. At small number of cyclic, cyclic plastic deformation depends on the pre-strain direction. The pre-strain perpendicular to cyclic loading directions results in large hardening at the same accumulated plastic strain value comparing with the pre-strains of the same direction as cyclic loading directions. The directional effect of pre-strain on cyclic loading with increasing number of cycles becomes small.