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2013
Journal Article
Titel
The effect of heat treatment on crack control and grain refinement in laser beam welded beta-solidifying TiAl-based alloy
Abstract
Investigations were conducted on the -TiAl-based alloy Ti-42Al-2.5Cr-1Nb-0.7Si-0.5B (at. %) to assess the influence of in situ and conventional post-weld heat treatment on the microstructure and microtexture transformations induced by laser beam welding. It was found that in situ post-weld heat treatment at 800 C was important to inhibit weld seam cracking. EBSD and HEXRD results indicated that the welding zone mainly consisted of coarse alpha 2 "textured colonies". These textured 2 are found to be in Burgers orientation relationship with their parent beta grains. After 1 h of conventional post-weld heat treatment at 1200 ÂșC followed by furnace cooling, the textured colonies are refined. The alpha 2 grains nucleate heterogeneously on borides so that the sharp texture of the weld zone was broken down.