Stress Relaxation Behaviour and Creep Constitutive Equations of SA302Gr.C Low-Alloy Steel

In order to study the stress relaxation behaviour of SA302Gr.C low-alloy steel, the stress relaxation experiments were performed at the temperatures of 400, 500 and 620 °C with the constant strain of 0.5 %. Based on the experimental stress relaxation curves, the relationship between creep strain rate and stress were derived and the creep strain rate–stress curves at different temperatures were obtained. Then, the creep constitutive equations at different conditions were developed and the constants in the equations were determined. In order to verify the developed creep constitutive equations, the finite-element (FE) model of stress relaxation of SA302Gr.C low-alloy steel was established with the FE software MSC.Marc. The comparison results show that the simulated stress relaxation curves agree with the experimental ones, which illustrates that the developed creep constitutive equations are appropriate for the tested steel.