Welding metallurgy of Alloy HR-160{reg{underscore}sign}
The solidification behavior and resultant solidification cracking susceptibility of autogenous gas tungsten arc fusion welds in Alloy HR-160{reg{underscore}sign} was investigated by Varestraint testing, differential thermal analysis and various microstructural characterization techniques. The alloy exhibited a liquidus temperature of 1,387 C and initiated solidification by a primary L {r{underscore}arrow}{gamma} reaction in which Ni, Si and Ti segregated to the interdendritic liquid and cosegregated to the {gamma} dendrite cores. Chromium exhibited no preference for segregation to the solid or liquid phase during solidification. Solidification terminated at {approximately} 1,162 C by a eutectic-type L{r{underscore}arrow}[{gamma}+(Ni,Co){sub 16}(Ti,Cr){sub 6}Si{sub 7}] reaction. The (Ni,Co){sub 16}(Ti,CR){sub 6}Si{sub 7} phase is found to be analogous to the G phase that forms in the Ni-Ti-Si and Co-Ti-Si ternary systems, and similarities are found between the solidification behavior of this commercial multicomponent alloy and the simple Ni-Si and Ni-Ti binary systems. Reasonable agreement is obtained between the calculated and measured volume percent of the [{gamma}+(Ni,Co){sub 16}(Ti,Cr){sub 6}Si{sub 7}] eutectic-type constituent with the Scheil equation using experimentally determined k values for Si and Ti from electron microprobe data. The alloy exhibited a very high susceptibility to solidification cracking in the Varestraint test. This is attributed to a large solidification temperature range of 225 C and the presence of 2--5 vol-% solute-rich interdendritic liquid that preferentially wets the grain boundaries and interdendritic regions.
- Research Organization:
- Lehigh Univ., Bethlehem, PA (US)
- Sponsoring Organization:
- US Department of Energy
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 20005574
- Journal Information:
- Welding Journal (Miami), Journal Name: Welding Journal (Miami) Journal Issue: 12 Vol. 78; ISSN 0043-2296; ISSN WEJUA3
- Country of Publication:
- United States
- Language:
- English
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