Nd-YAG Laser Beam-Induced Liquation Cracking in Selected Nickel-Based Superalloys

MAR-M247 and Rene 77 belong to intermetallic phase Ni3(Al, Ti) precipitation hardened nickel alloys widely used in the aerospace and power engineering industries. Because of their susceptibility to cracking, the above-named alloys are characterised by limited weldability. In the tests described in this article, the surfaces of the above-named superalloys were affected by a laser beam having identical parameters. Afterwards, the test results concerning the individual susceptibility to Nd-YAG laser beam-induced liquation cracking were compared. The stereoscopic microscopic observations revealed differences indicating the significantly greater crack susceptibility of superalloy MAR-M247. The characteristics of the materials indicated that the above differences were connected with the significantly more complex microstructure resulting from the segregation of alloying elements during crystallisation. The scanning microscopic examination revealed the presence of liquation cracks in the HAZ located along partially melted interdendritic areas.