Analysis of liquation and solidification cracks in the electron beam welding of GTD-111 nickel-base superalloy joint
Morteza Taheri, Seyed Farshid Kashani-Bozorg, Ali Alizadeh, Mohsen Heydari Beni, Jafar Eskandari Jam, Ali Khorram
Abstract
Abstract The weldability of GTD-111 superalloy by electron beam welding was studied, and the cracking evolution of solidification and liquation, as well as microstructural characteristics, were also investigated. The weld metal microstructure consisted mainly of the inter-dendritic phases of MC, γ - γ′ and γ′ nanoparticles, primarily responsible for the solidification crack in the weld metal. In addition to solidification cracks, the formation of liquation cracks in HAZ was an important challenge with electron beam welding. It was found that M 5 B 3 , γ - γ′ , MC and γ′ phases leave formation during the increase of non-equilibrium temperature in HAZ, with the formation of partial liquation in the phase-matrix interface and absorption of shrinkage stresses due to welding cooling. Both solidification and liquation cracks decreased as the heat input increased due to the increase in beam current. This was attributed to the reduction of cooling stress and the increase of backfilling capacity.