Numerical Simulation of Damage Evolution and Life Prediction for Two Commercial Fe-Cr-Ni Alloys Subjected to Mechanical and Environmental Factors

Associated with mechanical and environmental degradation, such as low-oxygen potential, high carbon activity, and high operating temperature, premature failure generally occurs in ethylene cracking furnace tube. This work is aimed at damage evolution numerical simulation and life prediction of two commercial Fe-Cr-Ni alloys (HP40Nb alloy and KHR45A alloy) under different operating temperatures, subjected to coupled carburization damage and creep damage. The results show that carburization is the most important factor that caused ethylene cracking furnace tube to rupture ahead of service time. Increased operating temperatures accelerate the damage rate markedly for the two alloys. For HP40Nb alloy and KHR45A alloy, the service life at 1223 K is almost 2.5 and 3 times higher than the value at 1323 K, respectively. Due to a higher mass of Ni/(Cr + Fe) ratio, the service life of KHR45A alloy is longer than that of HP40Nb alloy at the same operating condition. Distribution of von Mises stress σe and maximum principal stress σp along the inner surface and the outer surface of tubes is different to each other with damage evolution at different operating temperatures.