Precipitate Phases of Electron Beam Welded Joint in Superalloy Dissimilar Materials

Abstract

The precipitate phases of electron beam welded joint in GH141/GH907 superalloy dissimilar materials were studied by scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS). The welded joint contains GH141 heat affected zone, GH907 heat affected zone and weld area. The results indicate that there is no new precipitate phase in the heat affected zones of electron beam welding. Under the current heat treatment process, the precipitate phases of GH141 heat affected zone are square granular γ′ phases which are covered in matrix densely, thick massive MC type carbides with random distribution and the M6C type carbides which are precipitated mostly in the grain boundaries. Precipitate phases of GH907 heat affected zone are needle shaped ε phases covered in matrix densely and block G phases Nb3Ni2Si which are dispersed distribution. Precipitate phases of weld area are different from the two kinds of welding materials. One of them is a new needle shaped phase which has parallel or staggered distribution, and the other one is a tiny square or ellipsoid granular new precipitate phase which is proved to be orthogonal crystal system NbTi4 phase.

Keywords

• superalloys
• electron beam welding
• welded joint
• precipitate phase