Tracking heat-affected zone cracking susceptibility in standard and modified heat treated IN 738 superalloy welds
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Date
2014
Authors
Osoba, L.O.
Amuda, M.O.H.
Journal Title
Journal ISSN
Volume Title
Publisher
WIT Transactions
Abstract
The conditions influencing the phenomenon of heat affected zone (HAZ)
cracking during tungsten inert gas (TIG) welding of a gamma-prime (γ’)
precipitation strengthened nickel-base superalloy, IN 738, is discussed here. The
discussion is reinforced with the dependence of the cracking on particle size
variation of the γ’ precipitates and base alloy hardness. Microstructural analysis
of the magnitude of HAZ cracking in the alloy indicates that while resistance to
cracking susceptibility is poor in the standard heat treatment (SHT) condition,
the modified heat treated (MHT) alloy exhibits significantly improved resistance
to HAZ cracking. The improvement in resistance to HAZ cracking in the MHT
alloy is attributed to the lower hardness of the alloy which permits stress
relaxation in the base alloy compared to the SHT alloy. In contrast to what is
expected based on the recommended manufacturer SHT procedure, preweld
microstructural modification presents a viable way of limiting cracking
susceptibility in TIG welded IN 738 superalloy.
Description
Keywords
joining, superalloy, HAZ cracking
Citation
Osoba, L.O. and M.O.H. Amuda (2014). Tracking heat-affected zone cracking susceptibility in standard and modified heat treated IN 738 superalloy welds. WIT Transactions on The Built Environment; 137: 37-47