Influence of laser welding heat input on HAZ cracking in newly developed Haynes 282 superalloy

A study of the cause of heat affected zone (HAZ) cracking and its dependence on heat input during laser beam welding of a newly developed gamma' precipitation strengthened nickel based superalloy Haynes 282 was performed. Careful microstructural study coupled with Gleeble thermomechanical simulation showed that HAZ cracking in the alloy is attributable to the degradation of hot ductility of the alloy due to subsolidus grain boundary liquation. A decrease in the magnitude of heat input during laser beam welding resulted in increased HAZ cracking. The cracking variation with heat input is discussed in relation to the time that the subsolidus HAZ region spent at peak temperatures and thermally generated stress during welding.