Numerical Simulation on Properties Evolution of Cr35Ni45Nb alloy subjected to carburization and coking

By using a sequentially coupled thermal-stress procedure and finite element software ABAQUS code, distributions of temperature field and stress field of Cr35Ni45Nb alloy ethylene cracking furnace during the start-up process were simulated under the action of combined carburization and coking layer. And then effects of dimension of carburization layer and coking layer, different heat procedures on the thermal diffusion and mechanical property of Cr35Ni45Nb alloy were discussed. The results show that an accelerated decrease in the thermal diffusion property of Cr35Ni45Nb alloy is observed when the thicknesses of carburization layer and coking layer are increased. Furthermore, stress distribution is changed significantly along the interface of carburization layer, coking layer and metal matrix. The maximum circumferential stress is located along the inner surface of the alloy tube, while the minimum stress is situated along the outer surface, and this condition keeps constant with operating time increasing.