Prediction of liquation crack initiation at HAZ of laser weldment based on three dimensional strain analysis at elevated temperature

Abstract

The purpose of this study is to develop thermal and dynamic three dimensional strain analysis method for the laser weldment in order to obtain the plastic strain at elevated temperature in HAZ of the laser weldment, and to develop the prediction method of liquation crack initiation in HAZ of laser weldment. The U-type hot cracking test was performed as an experimental evaluation method for liquation cracking susceptibility of laser weldments of Inconel 718. At the same time, thermal and dynamic three dimensional elastplastic strain analyses were performed by FEM for U-type hot cracking test specimens. Heat transfer analysis and elastplastic strain analysis for laser weldments were confirmed by experiments. From this analysis, it becomes clear that the plastic strain at elevated temperature affects liquation crack initiation in HAZ, and the critical strain at elevated temperature, which controlled liquation crack initiation, can be calculated precisely by using this proposed analysis method.