High-Temperature constitutive modeling and tensile behavior of 17-4PH stainless steel

• Reveals 17-4PH steel’s high-temperature plastic behavior(860-900℃). • Spatial microhardness gradients identified near fracture surface. • T-Fields-Backofen model achieves 99% flow stress prediction accuracy. This study investigates the mechanical behavior of 17-4PH stainless steel during high-temperature tensile deformation at 860–900°C and strain rates of 1 × 10 -4 –2 × 10 -4 s −1 . Experimental results reveal that tensile strength decreases with increasing temperature and decreasing strain rate, while the fracture elongation increases with decreasing temperature and decreasing strain rate, reflecting enhanced ductility. Microhardness distributions exhibit pronounced spatial gradients, with a hardness gradient of 25–35 HV/mm along the tensile direction and a symmetrical transverse distribution with gradients of 20–25 HV/mm. A novel T-Fields-Backofen constitutive model, incorporating a strain rate–temperature coupling factor, was developed based on the Fields-Backofen framework to accurately predict flow stress during the strain hardening stage, achieving a prediction error of less than 2.4%.