Heat deformation analysis using a finite element model on gas pressure welding for steel bar

Abstract

Finite element model of gas pressure welding of steel bars is constructed in order to evaluate deformation behavior of the welded joint. The proposed model is based on a thermal-structural coupled analysis. Distribution of heat flux sourced from oxy-acetylene flame is assumed as a combination of two Gaussian functions, and heat losses due to convection and radiation are considered. Temperature dependences of thermal and mechanical properties of welding materials is modeled for the thermal-structural analysis. The analysis results show a good agreement with experimental results of variations of the temperature and the displacement on the weld center in the 20 MPa to 40 MPa range of the welding pressure. The proposed model revealed that tensile strain on the weld interface reaches larger value in the center than that in the outside of steel bar, depending on the temperature gradient. Additionally, the difference of the tensile strain between the center and the surface increases with increasing the upset force. It is considered that the temperature gradient on the weld interface is an important factor to control the deformation of gas pressure welded joint.