Effects of Prior Creep on Subsequent Plasticity of Type 316 Stainless Steel at Elevated Temperature

History effects of prior creep on subsequent plasticity were studied for type 316 stainless steel at 600°C under combined torsion and tension. Following each of three different amounts of prior torsional creep, plastic deformation tests were performed under torsions in the same and opposite directions of the prior creep and axial tension, respectively. The experimental results showed the marked influence of prior creep on subsequent plasticity. That is, the flow stress in the subsequent plastic deformation after creep became larger than the one in the corresponding pure plastic test where the prior creep strain in the combined creep-plasticity test was replaced by a plastic strain of the same amount. Finally, predictions by means of existing separated and unified constitutive equations were discussed on the basis of the experimental results.