Effect of pre-welding condition on liquation cracking characteristics of K439B superalloy laser welding

Le résumé fourni par la source

The liquation cracking is a crucial issue in the fusion welding of γʹ precipitation-strengthened nickel-based superalloys. In this study, the laser welding-induced liquation cracking of the newly developed cast superalloy K439B, and three pre-weld heat treatment conditions, have been investigated. The γʹ phase constitutional liquation and MC carbides constitutional liquation are the universal liquation mechanisms in K439B, and there are γ/γʹ eutectic liquation mechanism and partial incipient melting around η phase in the cast alloy. The pre-weld solution treatment increases the incipient melting temperature of the alloy due to the elimination of γ/γʹ eutectics and η phase. Applying a slower cooling rate after solution treatment changes the morphology and distribution of γʹ phase, softening the base material and increasing its ductility, reducing the cracking susceptibility. The over-aging treatment with the controlled cooling rate of 1 °C/min to 900 °C after solution treatment can suppress the liquation cracking of the K439B and achieve a crack-free laser welding joint.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.