Study on grain orientations and textures of laser welded 5A90 Aluminum-Lithium alloys using electron backscattered diffraction

摘要

The texture features of Nd:YAG laser welded joints in an Aluminum-Lithium (Al-Li) alloys were examined using electron back scattered diffraction (EBSD). Texture was determined by means of the grain orientation maps, pole figures (PF), misorientation angles and orientation distribution function (ODF) of the weld metal (WM), heat affected zone (HAZ) and unaffected base materials (BM) of the welded joint. A change of textures in the WM and HAZ of the welded joint was observed in terms of the component and intensity of the texture. The results show that the BM has a typical rolling state microstructure contained a mixture of large elongated grains and ultra-fine grains. A large fraction of low-angle grain boundaries can be observed on the BM having a typical cold-rolling texture for FCC metals with strong intensity. Characteristic of grain growth is presented for the elongated grains in the HAZ. High-angle grain boundaries are increased at this area as a result of the welding heat input. Texture in the HAZ inherits the texture characterization of the BM with the lower intensity. The welding heat input has an important influence on the component C {112}<111>. The WM is composed of predominantly equiaxed grains with a large fraction of high-angle grain boundaries and random texture. The complete fusion and solidification occurred in the WM change the rolling texture of the BM completely.