Effect of solid-liquid coexistence region on solidification cracking occurrence by U-type hot cracking test

摘要

Ni, Cr-based austenitic steels classified as 300 series are widely used because of good properties such as resist corrosion, good maintenance and maintain high strength at high temperature but susceptible to solidification cracking during welding. The hot cracking mechanism can be explained by thermal strain curve in weld beads. The solidification cracking occurs when the thermal strain curve intersects with the high temperature ductility curve of the material. The solidification cracking would be prevented if thermal strain curve decreased and does not intersect with high temperature ductility curve. In order to preventing solidification cracking the effect of temperature distribution region on thermal strain curve will be investigated.In this study the effect of solid-liquid coexistence region on solidification cracking was investigated by metallurgical analysis and thermal elastic-plastic analysis. The solid-liquid coexistence regions were changed by laser beam irradiation and the variation of thermal strain curves were investigated. The relationship between temperature distribution and thermal strain curve is clarified through this study.