Microstructure of Laser-Beam-Welded Iron-Based Superalloy A286 after High-Temperature Creep

Owing to their excellent high-temperature properties, ferrous superalloys are used in power plants and the aerospace industry. During high-temperature creep, these materials undergo distinct microstructural changes due to grain boundary sliding, fracture of grain boundaries, fracture of precipitates, and finally destruction by cracking of the material. The influence of laser-beam welding on the creep behavior is virtually unknown, in particular with respect to mechanical and microstructural properties. Here, the microstructure of a laser-beam welded superalloy was investigated after high-temperature creep deformation. First results show the conspicuous changes of microstructure due to laser-beam welding. The weld metal was identified to be textured. The dendrites within the weld metal showed a significantly lower hardness combined with a higher creep resistance than the base material.