International Journal of Materials Engineering and Technology
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Abstract: Heat Affected Zone (HAZ)
of TIG welded Ni base GTD 111 superalloys using various filler materials is
investigated. The characterization is done based on microstructure observation
and hardness estimation. The micro-hardness mapping indicates that the HAZ’s
are restricted to an area within 1 mm from the weld junction, independent
of filler materials used. The microstructure evaluation shows that size of which
precipitates coherently within the matrix, appear to be unchanged, while some MC
type carbides break-up are detected within the HAZ. Fine intergranular
microcracks associated with grain boundary liquation are observed at the weld
junction transverse to the weld bead. Detailed chemical analysis indicates that
the edge of cracks are Al and Ti rich, which are known to produceprecipitate
in Ni superalloy. It is suggested that liquation of along grain boundaries occurrs during welding and
contributes to HAZ cracking in GTD 111 similar to other report on precipitation
hardened Ni based superalloy.
