SA508 전자빔 잔류응력해석 시 상변태 영향 분석

This study analyzes the effect of solid-state phase transformation (SSPT) on finite element (FE) residual stress analysis. The SA508 Grade 3 Class 1 plate was used for the analysis. A cylindrical 3D heat source was applied for the thermal simulation, and the thermal model variables were determined using experimental temperature variation over time and the shape of fusion zone after welding. Stress analysis was performed based on the temperature gradient obtained from the thermal simulation, and the experimental residual stress of electron beam-welded SA508 was accurately reproduced with consideration of SSPT during simulation. The validated model was then used to investigate the effect of SSPT on welding residual stress. The results showed that longitudinal residual stress at the weld centerline was significantly overestimated, however, the transverse residual stress was acceptably reproduced. Consequently, the transverse residual stress might be estimated without consideration of SSPT, and the longitudinal stress should be analyzed with consideration of SSPT to improve the design margin for electron beam-welded structures.