1005 Development of Creep Constitutive Equation of Low Alloy Steel Pipe for Analysis of Stress Relaxation

Creep property has been specified for stress relaxation simulation in post-weld heat treatment (PWHT). Material property of low alloy steel was examined. First, creep tests were conducted at 400, 500, 600, and 700℃. Specimens were subjected to certain stresses, and creep strain rates were measured. Norton's law was used to specify the creep strain rates. Material property of Norton's law was calculated from the measured creep strain rates data. Then, relaxation tests were conducted at every creep test temperature. Again, specimens were subjected to certain strains, and stress relaxation was measured. The stress relaxation was simulated using Norton's law with the calculated material property. The simulation results agreed well with the measured data. Accordingly, the calculated material property in this study can be considered valid.