The mechanical threshold stress constitutive-strength model description of HY-100 steel

A generalized three-term mechanical threshold stress (MTS) strength model description, considering athermal, thermal, and strain-hardening contributions to flow stress, is employed to characterize the constitutive stress-strain response of HY-100 steel. Aspects of the MTS framework pertinent to United States Navy HY steels are discussed, and a calibration methodology is presented for determining MTS strength model parameters. In addition, a linear strain-hardening modification to the existing structure-evolution expression (flow-stress saturation) is proposed to better describe the large-strain strain-hardening behavior. Polycrystalline plasticity calculations suggest that the linear-like hardening behavior is a consequence of deformation-path-dependent texture evolution. Calculation results are applied to MTS model stress-strain predictions and, in part, help explain the differences between compression and torsion test data.