Numerical and Experimental Research on Distribution and Evolution of Coupling Residual Stresses Induced by Cutting-Welding Continuous Process

Abstract

Thermal cutting and welding are usually applied on component sequentially in shipbuilding, and the coupling residual stresses will be induced during this continuous process, which make the residual stress distribution different to that induced by single process. This research took a typical continuous process as the object: first, the mild steel plate was cut in half by oxygen flame, and then welded together. Based on the regression equations of initial residual stress distribution induced by cutting, a simplified numerical model was presented to investigate the distribution and evolution of coupling residual stresses with stress measurement validation based on X-ray diffraction. The research concluded that the distribution of coupling residual stresses, induced by cutting-welding continuous process, is mainly affected by the process, which can generate a wider distribution of high stresses. The evolution of coupling stresses is determined by the distance to seam (Γ1~Γ3)and the period undergoing (T1~T3), and the influence of initial residual stresses on coupling stresses was also investigated. 1. Introduction Shipbuilding consists of a series of processes applied sequentially, and the components of hull have to experience more than one process during shipbuilding, so the residual stresses in hull should be considered as the result of coupling effects between different processes, and it was named as coupling residual stress in this research. A typical kind of coupling residual stress in shipbuilding is induced by thermal cutting-welding continuous process, for example: first, the steel plates are cut into designed shapes, and then welded together to form the subassembly. During this continuous process, the coupling effects will be generated between the stress field of thermal cutting and the temperature field of welding, and superimposed with welding stresses. As a result, the cutting-welding coupling residual stresses will be presented. compared to the residual stresses induced by single process, coupling residual stresses need experience the evolution effected by much more factors, and finally have a more complex distribution. However, the residual stresses due to single process have gained most of the attention of researchers so far, and there is a lack of the studies on coupling residual stresses during continuous process (McPherson 2007).