The Effect of Nb and S Segregation on the Solidification Cracking of Alloy 52M Weld Overlay on CF8 Stainless Steel

Chu, Heng-Cheng; Young, M.C.; Tsay, L.W.; Chen, C.

doi:10.1007/s11665-013-0812-8

Cited by 10 publications

(5 citation statements)

References 14 publications

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“…Hot cracks were found to originate in the diluted zone near the weld interface in this work and in prior studies [18,21]. The solidification modes, microstructures, and morphologies of austenitic welds are known to be strongly affected by their compositions and Ni, Cr equivalents.…”

Section: Discussionsupporting

confidence: 67%

“…To prevent contamination with harmful elements from the CF8A substrate, 308L filler was deposited first onto the CF8A substrate as the buffer layer, followed by applying Ni-based fillers on the buffer layer. As reported in prior studies, introducing a buffer layer can lower the hot crack susceptibility of overlay welds effectively [18][19][20][21][22]. Figure 2c,d show the surface morphologies of 52M and 52MSS overlays with the 308L buffer layer.…”

Section: Materials and Experimental Proceduressupporting

confidence: 63%

“…It is reported that, among the distinct zones in a 52M overlay weld, the weld interface has the highest cracking tendency [18]. The hot cracking susceptibility of 52M overlay welds is strongly affected by contamination of impurity elements from the substrate during welding [19][20][21][22]. Decreasing the dilution rate of a dissimilar weld will be an effective way to mitigate hot cracking of 52M overlays [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…Decreasing the dilution rate of a dissimilar weld will be an effective way to mitigate hot cracking of 52M overlays [19,20]. In practical application, depositing proper buffer layers before a 52M overlay is applied decreases the number of hot cracks in the welds [21,22]. It is reported that for reducing hot crack sensitivity, a 307Si buffer layer is marginally better than a 308L one [23].…”

Section: Introductionmentioning

confidence: 99%

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The Comparison of Cracking Susceptibility of IN52M and IN52MSS Overlay Welds

Chen

et al. 2019

Metals

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Overlay-welding of IN52M and IN52MSS onto CF8A stainless steel (SS) was conducted by a gas tungsten arc welding process in multiple passes. An electron probe micro-analyzer (EPMA) was applied to determine the distributions and chemical compositions of the grain boundary microconstituents, and the structures were identified by electron backscatter diffraction (EBSD). The hot cracking of the overlay welds was related to the microconstituents at the interdendritic boundaries. The formation of γ-intermetallic (Ni 3 (Nb,Mo)) eutectics was responsible predominantly for the hot cracking of the 52M and 52MSS overlays. The greater Nb and Mo contents in the 52MSS overlay enhanced the formation of coarser microconstituents in greater amounts at the interdendritic boundaries. Thus, the hot cracking sensitivity of the 52MSS overlay was higher than that of the 52M overlay. Moreover, migrated grain boundaries were observed in the 52M and 52MSS overlays but did not induce ductility dip cracking (DDC) in this study. amount of interdendritic phases [25]. Coarse (Nb,Ti)C precipitates in 52M overlays will enhance the formation of Laves phases and increase their size [25,26], leading to increased hot crack sensitivity of the overlay welds.Besides the occurrence of hot cracking, Ni-based deposits for repair-welding of nuclear reactor components can be susceptible to ductility dip cracking (DDC) [27][28][29]. DDC in a Ni-based alloy weld mainly occurs in the reheated weld at elevated temperatures, and it is related to grain boundary (GB) sliding, impurity segregation at GBs, and intergranular precipitation [30]. GB sliding is responsible for the DDC of 52M deposits in strain-to-fracture tests [31]. Moreover, ductility dip cracks are initiated due to the combined effects of the strain concentration on the concave side of the grain boundary, the orientation of the GB to the loading direction, and GB disorientation [32]. In a prior study, IN52 alloy is reported to be more susceptible to DDC than IN82 alloy [33]. Adding Nb and Ti into IN52 alloy can reduce its DDC susceptibility due to the precipitation of NbC and TiC at the GBs [30]. It was reported that the DDC of a 52MSS weld, which was modified from 52M by adding 2.5% Nb and 3.0% Mo, can be alleviated even after multi-pass welding [34,35].In this study, IN52M and IN52MSS fillers were employed to perform overlay-welding on CF8A SS substrate. The microstructures and chemical compositions of the microconstituents at the solidified boundaries of the overlay welds were investigated. The hot cracking tendency and DDC of 52M and 52MSS overlays were evaluated by inspecting the interior microfissures carefully. Grain boundary micro-constituents were analyzed by electron backscatter diffraction (EBSD) to identify the complex phases. Furthermore, the relationships between microstructural features and the cracking tendencies of the overlay welds were correlated with those interdendritic precipitates.

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Section: Discussionsupporting

confidence: 67%

Section: Materials and Experimental Proceduressupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Comparison of Cracking Susceptibility of IN52M and IN52MSS Overlay Welds

Chen

et al. 2019

Metals

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“…9 Collins and co-workers observed some TiN nitrides and eutectic constituents when they investigated the ductility dip cracking in filler metal 52, and they proposed the eutectic constituents to be c/MC or the mixture of c/MC and c/Laves according to the study of DuPont et al 10 Chu et al found that there were three different types of eutectic type constituents that formed during solidification of filler metal 52M, and the eutectic constituents were deduced to be c/NbC(N), c/Laves and c/(Fe-Ni-S) in the solidification cracking study of alloy 52M weld overlay. 11 McCracken et al reported that in 52MSS, the eutectic constituent that formed in the end of solidification was c/NbC. 12,13 Although several investigations have been conducted on these specific high chromium nickel base alloys consumables, researches about the solidification sequence and microstructural evolution of the high chromium nickel base alloys were limited.…”

Section: Introductionmentioning

confidence: 99%

Solidification behaviour of a high chromium nickel base alloy weld deposited metal

Chen

2015

Science and Technology of Welding and Joining

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The solidification behaviour including microsegregation and secondary phase formation of a high chromium nickel base alloy weld deposited metal was examined with optical microscopy, scanning electron microscopy and transmission electron microscopy. Microsegregation potential of major alloying elements in the weld deposited metal was investigated. The microconstituents formed during solidification were identified to be TiC and c/Laves eutectic constituent. Most c/ Laves eutectic constituents were located at the dendrite interstices due to the microsegregation of Nb, Mo and Si. The volume percent of c/Laves constituent was predicted by using Scheil equation, and there was a reasonable agreement between the predicted and measured value. Last, two possible solidification paths added to the c-Nb-C pseudoternary solidification diagram were proposed to analyse the solidification sequence of the new high chromium nickel base alloy.

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The Segregation and Liquation Crackings in the HAZ of Multipass Laser-Welded Joints for Nuclear Power Plants

Zhu

et al. 2017

J. of Materi Eng and Perform

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The Effect of Nb and S Segregation on the Solidification Cracking of Alloy 52M Weld Overlay on CF8 Stainless Steel

Cited by 10 publications

References 14 publications

The Comparison of Cracking Susceptibility of IN52M and IN52MSS Overlay Welds

The Comparison of Cracking Susceptibility of IN52M and IN52MSS Overlay Welds

Solidification behaviour of a high chromium nickel base alloy weld deposited metal

The Segregation and Liquation Crackings in the HAZ of Multipass Laser-Welded Joints for Nuclear Power Plants

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