Multiaxial Inelastic Deformation of 316 FR Steel at High Temperature and Application of Viscoplasticity Theory.

Inelastic deformation of 316 FR stainless steel are experimentally investigated under the cyclic nonproportional loading conditions, with a combination of cyclic push-pull and cyclic torsion, at 923 K. The magnitude of the cyclic hardening under nonproportional loading is quite larger than that observed under uniaxial push-pull or proportional loading (Additional Hardening) and it was found that this additional hardening strongly depends on the strain rates. The viscoplasticity theory based on overstress (VBO) by Krempl which was extended to the uniaxial cyclic deformation of the present material at 923 K by one of the authors is extended to reproduce these interesting behaviors observed under biaxial nonproportional loading. Good agreement is found between the simulation by the present model and the experimental results.