Papers by Author: M. Yamamoto

Abstract: Liquid Penetration Induced (LPI) cracking during AZ91, AZ31 and AM60 friction stir spot welding is investigated. The temperature cycles, within the stir zone and in the TMAZ region, are examined. The mechanism and the key factors determining LPI cracking in Mg-alloy friction stir spot welds are delineated.

Abstract: This study was carried out on the development of the evaluation method for solidification cracking susceptibility of Inconel600/SUS347 dissimilar weld metals during laser welding. Some dissimilar weld metals which have different ratios of Inconel600/SUS347 were prepared by TIG welding and then were remelted on the U-type hot cracking tester by laser. Solidification cracking behavior during hot cracking test was observed by a high speed camera and the dynamic strain, close to the solidification crack, was evaluated. It appeared that local critical strain, for the initiation of solidification crack, was obtained by this strain measurement method. So the solidification cracking susceptibility could be directly evaluated based on the critical strain for different dissimilar joint. By using this method, it was discovered that solidification cracking occurred most easily when the ratio of Inconel600/SUS347 is 40%/60%, in the case of the Inconel600/SUS347 dissimilar laser welded joints.