局所冷却を伴う温度場で生じる溶接残留変形とその低減効果

Abstract

It is well known that weld distortion, which has a negative influence on material properties, structural fabricability, and structural integrity, should be controlled appropriately. There are many methods to control or reduce weld distortion, but most of them involve some costly process in addition to welding. In-process control of weld distortion becomes more preferable than post-welding process or other methods, when manufacturing efficiency is considered. In recent years, in-process control welding by additional cooling has been proposed as one of techniques for reducing weld distortion and partially applied for thin-plate structure in industries. However, the effectiveness of additional cooling method has not yet been fully clarified.In this study, the effectiveness of additional cooling method and appropriate cooling condition for effective reduction of weld distortion are investigated by three-dimensional thermal elastic-plastic analysis. In addition, the effect of locally cooled temperature distribution on generation behavior of plastic strain is discussed. As the result, it is concluded that the effectiveness of additional cooling and appropriate cooling condition for reduction of weld distortion are dependent on weld distortion under consideration and welding conditions. Especially, it is necessary for reduction of weld distortion to set the cooling torch at the appropriate position. For example, in order to reduce angular distortion effectively, the appropriate cooling position is dependent on the mechanical melting length during welding.