Determination of Johnson–Cook Constitutive and Failure Parameters for Cr20Ni80 Alloy Using an Experimental–Numerical Approach

Accurate numerical simulation of Cr20Ni80 alloy processing relies on reliable constitutive and failure models. This study employs a comprehensive experimental–numerical approach to calibrate and validate the Johnson–Cook (J-C) parameters of Cr20Ni80 alloy under varying stress states and strain rates. Quasi-static tensile tests on smooth and notched specimens, alongside dynamic Split Hopkinson Tension Bar (SHTB) tests (1000–3000 s−1), were conducted. Pulse-shaping technology was employed, and dynamic force balance was verified to ensure the physical validity of the high-strain-rate data. The constitutive parameters (A=621.02 MPa, B=543.20 MPa, n=0.4564, C=0.0141) were determined based on true stress–strain responses. Theoretical analysis confirms that the thermal softening effect caused by adiabatic heating can be neglected. Furthermore, the failure parameters (D1=−0.4300, D2=2.6405, D3=−0.7055) were calibrated to capture the stress triaxiality effects (R2=0.978). The parameter D4 was iteratively calibrated using SHTB data from the 1000 s−1 and 3000 s−1 test conditions and validated using SHTB data from the 2000 s−1 test condition. The engineering stress–strain curves obtained from simulations using the calibrated parameters showed good agreement with experimental results, confirming the reliability of the calibrated parameters.