Experimental and Numerical Study on Creep Behavior of TP321 Austenitic Stainless Steel at 650 °C

TP321 austenitic stainless steel is a type of creep-resistant material with a wide range of applications, including in boilers and nuclear reactors. This paper investigates the creep behavior and damage mechanism of the material at 650°C and stress levels of 145-245 MPa through creep tests and microstructural observations. The experimental results demonstrate a reduction in creep rupture times with increasing stress level. Creep voids nucleate and grow in the triple joints during creep, and then the voids continuously aggregate to form microcracks, ultimately leading to fracture. The applicability of three different creep life prediction methods is assessed, with the Larson–Miller parameter method being the most accurate, followed by the Shesterikov method, the Monkman–Grant relationship method, and the modified Monkman–Grant relationship method. Finite element simulations are performed based on the Kachanov–Rabotnov creep continuum damage model, and the simulation results are found to be in good agreement with the experimental results. The findings of this work provide a scientific basis for understanding the creep behavior of TP321 austenitic stainless steel at 650 °C, offering critical design data for high-temperature components in advanced nuclear reactors operating beyond this temperature threshold. Future work will refine life prediction models to enhance accuracy for extreme-temperature applications.