Reduction of the hot cracking sensitivity of CM-247LC superalloy processed by laser cladding using induction preheating

Abstract

In the present work, the repair of CM-247LC superalloy has been investigated by using a laser cladding process. Since this material is well known for its high hot-cracking susceptibility in Heat Affected Zone during welding, repairing is quite challenging. In a first stage, a detailed investigation of the effect of cladding parameters on the crack susceptibility was carried out on coupons that received a low pre-heating condition. However, despite a reduction of crack sensitivity for low energy inputs, this material has systematically shown some evidence of cracking in the HAZ. In a second stage, attempts were made to reduce crack defects by using an induction preheating, with higher temperatures in the range of 800–1100 °C. With the highest pre-heating temperatures near 1100 °C, the partial dissolution of large γ’ precipitates, combined with re-precipitation of secondary and smaller γ' precipitates were helpful to prevent hot cracking.