Serrated Flow Behaviour of 2.25Cr-1Mo Steel Base Metal, Weldments and Simulated Heat Affected Zone Structures

Laha, K.; Chandravathi, K.S.; Rao, K.B.S.; Mannan, S.L.

doi:10.1515/ijmr-1994-851207

Cited by 1 publication

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“…The dissolution of Mo 2 C carbides within this region during the weld thermal cycle has also been cited as a contributing factor to early fracture. [56][57][58][59] The DMW appears to provide better creep life than the similar weld at high stresses and short rupture times. However, at stresses below y130 MPa, the life of the DMW is below that of the similar 2?25Cr-1Mo weld.…”

Section: Creep Rupture Propertiesmentioning

confidence: 99%

Microstructural evolution and high temperature failure of ferritic to austenitic dissimilar welds

DuPont

2012

International Materials Reviews

126

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Dissimilar metal welds between ferritic and austenitic alloys are used extensively in power plants.Premature failure of such welds can occur below the expected creep life of either base metal. This article reviews microstructural evolution in dissimilar welds and describes factors that contribute to premature failure. The microstructure in the as welded condition consists of a sharp chemical concentration gradient across the fusion line. Martensite forms within this gradient due to high hardenability and rapid cooling rates from welding. Upon aging, carbon diffuses down the chemical potential gradient from the ferritic steel toward the austenitic alloy. This can lead to formation of a soft carbon denuded zone in the ferritic steel, and nucleation and growth of carbides in the austenitic steel that produce high hardness. These differences in microstructure and hardness occur over distances of about 50-100 mm. Failure is attributed to the steep microstructural and mechanical property gradients, the large difference in coefficient of thermal expansion, formation of interfacial carbides that promote creep cavity formation, and preferential oxidation of the ferritic steel. Information is also provided on available creep rupture properties, remaining life estimation techniques, current best practices and research in progress.

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Section: Creep Rupture Propertiesmentioning

confidence: 99%