Simulation of wave propagation in austenitic stainless steel welds with solidification structure predicted by Cellular Automaton method

Abstract

Austenitic stainless steel is widely used in nuclear power plants (NPPs) and a variety of occurrences of stress corrosion cracking (SCC) near its weld have been reported among NPPs. Ultrasonic testing is a critical technique for the detection and depth sizing of SCCs. However, such welds' anisotropic and heterogeneous properties cause difficulties in ultrasonic testing when ultrasonic waves propagate through welds. Deeply understanding the characteristics of ultrasonic waves with wave propagation simulation is effective to improve the accuracy of ultrasonic testing. To this end, it is necessary to take crystal orientation and grain boundary into account simultaneously in the numerical model. In this study, a model was developed so that the Cellular Automaton (CA) method can simulate the solidification structure from multilayer and multipass welding process, then the solidification structure of a 7-layer and 7-pass weld of austenitic stainless steel was predicted based on welding conditions. Finally, the finite element method was used to compute wave propagation in austenitic stainless steel weld with the solidification structure predicted. Numerical results of wave propagation in austenitic stainless steel weld were compared to those obtained by experiment.