The structure of the heat-affected zone in welds of a Ni-29 wt. % Mo commercial alloy (Hastelloy B2)
- Univ. of Tennessee, Knoxville, TN (United States)
- Tennessee Eastman Corp., Kingsport, TN (United States)
The microstructure of a welded pipe of Hastelloy B2 removed from a coal gasification plant was examined. Although this alloy is susceptible to severe embrittlement if ordering occurs, no significant ordering was found in the heat-affected zone (HAZ) or the weld, and the material was ductile. However, intergranular corrosion was found in the HAZ, and fine (e.g., 0.1mm) particles of Mo-rich M[sub 12]C carbide and the intermetallic compound NiMo were found in the grain boundaries. These are apparently depleting the adjacent matrix of Mo, rendering the grain boundary region susceptible to corrosion. A single- and a double-pass autogeneous weld made on the base-plate material were examined. No ordering was detected in the HAZ, which is consistent with the measured temperature-time curves of regions adjacent to the weld and with the known ordering kinetics. In the HAZ, fine grain boundary particles of M[sub 12] carbide were detected, and NiMo may also be present.
- OSTI ID:
- 7073120
- Journal Information:
- Materials Characterization; (United States), Vol. 33:1; ISSN 1044-5803
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
01 COAL, LIGNITE, AND PEAT
COAL GASIFICATION PLANTS
PIPES
HASTELLOYS
INTERGRANULAR CORROSION
MICROSTRUCTURE
HEAT AFFECTED ZONE
CHEMICAL COMPOSITION
EXPERIMENTAL DATA
WELDED JOINTS
ALLOYS
CHEMICAL REACTIONS
CORROSION
DATA
INDUSTRIAL PLANTS
INFORMATION
JOINTS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NUMERICAL DATA
ZONES
360102* - Metals & Alloys- Structure & Phase Studies
360105 - Metals & Alloys- Corrosion & Erosion
010404 - Coal
Lignite
& Peat- Gasification