移動熱源の影響に注目した入熱パラメータと角変形の関係に関する一考察

抄録

In recent years, it has become much more necessary to control or reduce weld distortion, which has negative influences on structural integrity, without loss of manufacturing efficiency. Higher accurate prediction of weld distortion brings in one of contributions for improvement of manufacturing efficiency.
Commonly, angular distortion, which is controlled by temperature distribution along direction of plate thickness, is controlled by heat input parameter (Q_net / h²). However, it is also known that there are several concerns against applicability of conventional heat input parameter for prediction of angular distortion. One of concerns is the effect of welding speed. This is because that the conventional heat input parameter is derived from welding thermal conduction theory without considering moving of weld heat source. Actually, pre-study by experiment about effect of welding conditions, including welding speed, on angular distortion has shown that angular distortion is not always controlled by heat input parameter in case of different welding speed. Then, in order to clarify the effect of welding speed on that, more detailed study is further required.
In this paper, numerical study on the effect of welding speed on relationship between heat input parameter and angular distortion are performed based on the past experimental results. In addition, the reason why the relationship between heat input parameter and angular distortion is affected by welding speed is discussed from a viewpoint of distribution of the maximum temperature rise and residual plastic strain. It is concluded that the effect of welding speed on relationship between heat input parameter and angular distortion is understood by the difference in distribution of mechanical melting temperature, which identifies the distribution of residual plastic strain for angular distortion, in plate thickness section.