A microcracking in 35Ni-20Cr-2Mo-3Cu-lNb alloy multi-layer weld metal had been investigated by a hot cracking test applying enforced strain and metallurgical examination. The microcracking of this weld metal was a liquation cracking which occured above 1100°C on heating and above 1050°C during cooling. It is considered that this liquation cracking was induced by eutectic remelting between NbC and matrix on austenite grain boundary. In order to prevent the microcracking the degrease of the amount of NbC in a weld metal is necessary, and it is desirable to lower C content in a welding material less than 0.002%.
