2009 年 27 巻 2 号 p. 139s-143s
This study is purposed to develop a systematic method for prediction of solidification cracking during laser welding by accurately obtaining the high temperature ductility and weld strain of weld metal. The U-type hot cracking test was carried out under various initial loads; solidification cracking behavior was in-situ observed by a high speed camera so that the critical strain, for the initiation of solidification crack, was measured precisely. With the critical strain and temperature history measured at the solidification crack, the high temperature ductility curve was achieved. Meanwhile, a three dimensional FEM-analysis was performed to obtain the detailed strain history at the crack initiation point during laser welding. In order to get the accurate strain history, it is necessary to obtain the accurate material properties of weld metal at the elevated temperature up to solidification temperature range. The FEM-analysis was carried out by using the obtained high temperature material properties, which were measured by a developed high temperature tensile test with in-situ observation. Therefore, it became possible to predict the occurrence of solidification cracking during laser welding accurately by using both of the detailed high temperature ductility curve measured experimentally and the strain history obtained by the 3D FEM-analysis.
