Effect of pre-welding heat-treatments on welding a two-phase Ni{sub 3}Al alloy
Conference
·
OSTI ID:10162543
- Associated Western Univ., Richland, WA (United States)
- Pacific Northwest Lab., Richland, WA (United States)
Autogenous gas-tungsten arc welding was performed on a two-phase Ni{sub 3}Al alloy. Plates 3 mm thick were subjected to three pre-welding heat treatments (PWHT): as-cast, annealed at 1100C for 23 h (HT1) and HT1 plus 1120C/30 min/air cool (HT2). As-cast alloy was characterized by dendrites with many eutectic cells located at dendrite boundaries (DBs). The eutectic cells were destroyed by HT1. However, HT2 make no further changes on microstructure. Energy dispersive X-ray spectroscopy (EDX) revealed that the DBs of as-cast alloy were enriched with Zr. The Zr enrichment at DBs was increased further by HT1 and HT2. No solidification crack visible to the unaided eye was found in either fusion zone (FZ) or heat-affected zone (HAZ) due to welding. The FZ consisted of columnar grains with a eutectic structure along the boundaries. The eutectic structure was enriched with, Zr and contained many microcracks and some Zr-rich phases. Micro-solidification cracks were occasionally found along boundaries in FZ. The alloy was sensitive to liquation cracks that occurred along DBs in the HAZ. While PWHT had no effect on the characteristics of the FZ, PWHT had a notable effect on the severity of liquation cracking. The average crack numbers per 5 cm weldment were 12 for as-cast, 14 for HT1, and 17 for HT2. The role of Zr-inducing solidification cracks in FZ and liquation cracks in HAZ is discussed.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 10162543
- Report Number(s):
- PNL-SA--22934; CONF-940598--2; ON: DE94014409
- Country of Publication:
- United States
- Language:
- English
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