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The effect of heat treatment on crack control and grain refinement in laser beam welded beta-solidifying TiAl-based alloy

 
: Liu, J.; Dahmen, M.; Ventzke, V.; Kashaev, N.; Poprawe, R.

:

Intermetallics 40 (2013), S.65-70
ISSN: 0966-9795
Englisch
Zeitschriftenaufsatz
Fraunhofer ILT ()

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 ºC 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.

: http://publica.fraunhofer.de/dokumente/N-241676.html