Improved Resistance to Laser Weld Heat-Affected Zone Microfissuring in a Newly Developed Superalloy HAYNES 282
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Date
2012
Authors
Osoba, L.O.
Ding, R.G.
Ojo, O.A.
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The Minerals, Metals & Materials Society and ASM International
Abstract
Gleeble thermomechanical simulation and microstrucutural analyses of laser beam weldability
of a newly developed precipitation-hardened nickel-base HAYNES alloy 282 were performed to
better understand the fundamental cause of heat-affected zone (HAZ) cracking and how to
prevent the cracking problem in the material. Submicron size intergranular M5B3 particles are
identified for the first time in the present work by transmission electron microscopy, and were
found to be the primary cause of HAZ grain boundary liquation cracking in the alloy. Complete
dissolution of the liquating M5B3 particles by preweld heat treatment exacerbated rather than
reduced susceptibility to cracking, which could be attributed to nonequilibrium intergranular
segregation of boron atoms, liberated by the complete dissolution of the boride particles, during
cooling from heat treatment temperature. Consequently, to reduce the HAZ cracking, a preweld
heat treatment that reduces the volume fraction of the M5B3 particles while minimizing nonequilibrium grain boundary boron segregation is necessary, and this is possible by heat treating
the alloy at 1353 K to 1373 K (1080 C to 1100 C). Further improvement in cracking resistance
to produce crack-free welds is achieved by subjecting the alloy to thermomechanically induced
grain refinement coupled with the preweld heat treatment at 1353 K (1080 C). A Gleeble hot
ductility test showed that formation of the crack-free welds is unexplainable by mere reduction
in grain size without considering the effect of grain refinement on intergranular liquid produced
by subsolidus liquation of the M5B3 borides.
DOI: 10.1007/s11661-012-1212-7
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Osoba, L.O. Ding, R.G. Ojo, O.A. (2012). Improved Resistance to Laser Weld Heat-Affected Zone Microfissuring in a Newly Developed Superalloy HAYNES 282. The METALLURGICAL AND MATERIALS TRANSACTIONS A; 43A: 4281-4295