Numerical Investigations on Residual Stress in Laser Penetration Welding Process of Ultrafine‐Grained Steel

Abstract

Weld solidification crack prevention in the laser penetration welding process is essential for the strength of the welded component. The formation of solidification cracks can ultimately be attributed to welding residual stresses, and preventive measures should be taken during welding. In this study, the effects of residual stresses on the laser penetration welding quality of ultrafine-grained steels were investigated. A heat source model was established through the analysis of the metallography of the cross section of the heat-affected zone (HAZ) of ultrafine-grained AN420s-grade steel, and the chemical composition of the weld bead was obtained using an FLS980-stm Edinburgh fluorescence spectrometer. Furthermore, the constitutive coupling relation between the temperature and material flow stress was established based on the Gibbs function, and the welding residual stress was obtained by setting trace points in a finite element analysis (FEA) model based on experimental data of the weld bead cross section under different welding conditions. The results show that weld solidification cracks will form when the residual stresses exceed the material flow stresses in the weld bead, and the residual stresses can be decreased through a reasonable increase of the welding speed. The results indicate that the proposed criterion has high accuracy and can be used to predict the formation of weld solidification cracks in the laser penetration welding process.

Characterization of Crack Tip Mechanical Field of Inhomogeneous Materials in Welded Joints by USDFLD Subroutine

“…Because of the intensity of welding process, the metals near heat source are signi cantly a ected by the temperature, resulting in uneven distribution of the material microstructure of the welded joint [1][2][3]; thus, under the interaction of residual stress, nonuniformity of mechanical properties of microstructure, and other complex mechanical and environmental factors, micro-cracks are easy to occur in welded joints, such as welding hot breaking, cold crack, reheat crack, lamellar tearing, and stress corrosion crack, which has become a potential safety hazard in the service process of welded joints. erefore, the welded joints are the key areas of structural integrity analysis, and local mechanical heterogeneity needs to be properly expressed.…”

Prediction of Preheating Temperatures for S690QL High Strength Steel Using FEM-Simulation for High Power Laser Welding

“…Hence, the unwanted effects are a function of the process conditions. For instance cracks can occur at different process parameters [5] and the formation of pores can be reduced by the process parameters as well [6].…”

Estimating the Influences of Prior Residual Stress on the Creep Rupture Mechanism for P92 Steel

“…Furthermore, the numerical methods based on the damage model combined with experimental tests can provide an efficient way to analyse the effect of stress levels on creep crack growth and rupture. It should be noted that some researchers [18,19] have attempted to describe the process of high-temperature deformation of metallic materials through the use of material intrinsic flow stress. In reference [18], the thermal deformation behavior and the hyperbolic constitutive equation of T122 steel were investigated by the determination of deformed activation energy and material intrinsic flow stress.…”

“…In reference [18], the thermal deformation behavior and the hyperbolic constitutive equation of T122 steel were investigated by the determination of deformed activation energy and material intrinsic flow stress. In reference [19], the relationship between residual stress and material intrinsic flow stress has been used to determine the formation of weld solidification cracks. On the basis of references [18,19], the method for exploring the effects of prior residual stress on the creep rupture mechanism through the comparison of residual stress and material intrinsic flow stress was conducted in this study.…”