Finite element and experimental analysis of residual stresses in G20Mn5 welded joints considering solid-state phase transformation

Abstract

Residual stress (RS) induced during the welding of steel structures can significantly affect their load-bearing capacity. Solid-state phase transformation (SSPT) is essential to the temperature and stress variations during welding, presenting challenges for accurate analysis. Many current numerical simulations overlook SSPT effects in thermal coupling and the key parameters are difficult to obtain. This study enhances the precision of welding simulations by establishing a prediction network for the kinetic parameters of SSPT and introducing a thermal-metallurgical-mechanical finite element program in ABAQUS, which incorporates SSPT. It explores the impact of SSPT on the welding of cast steel welded joints (CSJ). Initially, a predictive model based on the radial basis function (RBF) neural network is developed to determine the kinetic parameters of SSPT for relevant materials, enabling rapid and precise prediction of the base material's SH-CCT diagram. Subsequently, a multi-physics field coupled welding process calculation program is created in ABAQUS software, considering SSPT, latent heat, and associated expansion, its accuracy is validated through experimental cases. Ultimately, the study concludes that the volume change induced by SSPT reduces welding RS, while tensile RS, stress concentration, and welding defects on the inner surface of CSJ increase the risk of structural cracking at the weld root.