Determination of Johnson-Cook Constitutive and Failure Parameters for Cr20Ni80 Alloy Using an Experimental-Numerical...

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.