Solidification cracking of a nickel alloy during high-power keyhole mode laser welding

Abstract

Nickel alloy Inconel 740H, a candidate material for use in ultra-supercritical power plants, is susceptible to solidification cracking during high power deep penetration laser welding. Here we examine how cracking is affected by welding variables and determine the locations where the cracks occur experimentally and theoretically. We use a solidification cracking model to calculate the effects of welding variables on cracking and the locations where the cracks form during high power laser keyhole mode welding of IN 740H. The parameters needed for the cracking model are obtained from a well-tested numerical heat transfer and fluid flow model for keyhole-mode welding. Model predictions of cracking and their locations for different welding conditions are verified by experiments. • Solidification cracking of nickel alloys during laser welding is poorly understood. • We propose a novel methodology to understand why, when, and where cracking occurs. • A heat and fluid flow and solidification model, and experimental data are used. • Model predictions of cracking locations and conditions are verified by experiments. • The work can be used to prevent weld failures in thick section laser keyhole welds.