Creep damage of weldments in 1Cr-0.5Mo steels during long term service at elevated temperature

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Scripta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-716X(95)00203-8· OSTI ID:103587

Lee, Y J ^[1]; Muddle, B C ^[2]

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1. Agency for Defense Development, Taejon (Korea, Republic of). Advanced Technology Research Center
2. Monash Univ., Clayton, Victoria (Australia). Dept. of Materials Engineering

The cracking of 1Cr-0.5Mo steel stub welds from the Electricity Commission of New South Wales (E.C.N.S.W.) 3rd stage superheater outlet header occurs almost exclusively within the heat affected zone (HAZ). The cracking is intergranular and follows prior austenite grain boundaries. There is extensive cavitation along prior austenite grain boundaries adjacent to and ahead of these cracks. There is an enhanced concentration of MnS inclusions confined almost exclusively to the HAZ of those stub welds from the E.C.N.S.W. header exhibiting cracking. This is attributed to an effective overheating of the HAZ during weld formation, leading to dissolution and then re-precipitation of MnS particles at prior austenite grain boundaries during heating and cooling cycles, respectively. Techniques of scanning electron microscopy, and transmission electron microscopy of extraction replicas from both fracture surfaces and polished and etched sections, have been used to identify the presence of a large volume fraction of sub-micron MnS particles at prior austenite grain boundaries in the HAZ of cracked weldments. Coarse carbides have also been identified at these boundaries, the most common carbides being M{sub 7}C{sub 3} and M{sub 3}C.

• OSTI ID: 103587
• Journal Information: Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 3 Vol. 33; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUSTENITE
CARBIDES
CRACKS
CREEP
DAMAGE
GRAIN BOUNDARIES
HEAT AFFECTED ZONE
LOW ALLOY STEELS
MANGANESE SULFIDES
MICROSTRUCTURE
MORPHOLOGY
OPTICAL MICROSCOPY
PRECIPITATION
SCANNING ELECTRON MICROSCOPY
TRANSMISSION ELECTRON MICROSCOPY
VANADIUM ADDITIONS
WELDED JOINTS