Liquation cracking in fiber laser welded joints of inconel 617

•Most liquation crackings are prevalent in the neck zone region of welded fusion zone.•The mechanism of grain boundary liquation is analyzed.•The formation of the continuous (Cr, Mo)-rich resolidified phase is investigated.•HAZ liquation cracking is decreased by increasing heat input.•Liquation cracking is decreased by preheating base material in the laser welding.

Liquation cracking in the fiber laser welding Inconel 617 joint under different heat input and preheating conditions was systemically investigated. Liquation cracking is prevalent in the necking region of the welded fusion zone. The liquation of the grain boundaries (GBs) is mainly caused by the constitutional liquation of M23(C,B)6 carbides. The continuous (Cr, Mo)-rich phase is re-solidified due to the continuous liquid film along GBs during the solidification. The continuous (Cr, Mo)-rich phase decreases as the heat input and preheating temperature increases. The presence of the GB resolidified phase around liquation cracking is one of the features in the formation of liquation cracking. As well as, liquation cracking in heat affected zone (HAZ) would also decrease with increasing heat input and preheating temperature in the fiber laser welding of Inconel 617.