Residual Stress and Distortion Analysis for TMCP Steel Grade EH36 Butt Welding Parts in GTAW-SMAW Hybrid Welding Process using Finite Element Method

Abstract

The present work evaluates residual stress and distortion in Thermo-Mechanical Control Process (TMCP) grade EH-36 steel plates subjected to hybrid Gas Tungsten Arc Welding (GTAW) and Shielded Metal Arc Welding (SMAW) processes Specimens measuring 650 × 170 mm with a thickness of 12 mm were utilized. Finite Element Method (FEM) analysis was employed to model residual stress and distortion, a critical step in optimizing the manufacturing process of mechanical structures and parts in shipbuilding. The FE model was developed using ANSYS software incorporating a heat source model with a user-defined subroutine to represent an ellipsoidal moving weld torch with front and rear power density distribution. Heat losses due to radiation and convection were accounted for, while mechanical boundary conditions were applied to restrict rotation and displacement but allow material deformation. Thermal analysis demonstrated close agreement between experimental thermocouple data and numerical simulations, with a temperature deviation of only 5%. Residual stress analysis using X-Ray Diffraction (XRD) revealed that ultrasonic stress relief reduced the maximum residual stress from an average of 193.4 MPa to 39.1 MPa Distortion analysis showed that the maximum FEM deformation was 0.2873 mm, with a 12% deviation from coordinate measuring machine (CMM) results, while the minimum FEM deformation was 0.031922 mm, differing by 3%. The larger deviation occurred in areas with peak distortion, attributed to variations in mechanical restraint positioning, which significantly influence material deformation during cooling.