Welding technologies for ultra-supercritical power plant materials

Sorrentino, S.

doi:10.1016/b978-0-08-100552-1.00009-9

Cited by 13 publications

(5 citation statements)

References 9 publications

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“…Many countries have accelerated the construction of advanced ultra-supercritical (AUSC) thermal power units with high steam temperatures and pressure in order to achieve high energy efficiency with minimal carbon footprints 1 – 3 . The AUSC technology is one of the recent technologies for next-generation power units, which have great potential for energy conservation and can be commercialized with efficiency up to ~ 50% 4 .…”

Section: Introductionmentioning

confidence: 99%

Structural integrity assessment of Inconel 617/P92 steel dissimilar welds for different groove geometry

Kumar

Pandey

2023

Sci Rep

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The work is focused on examining the effect of the weld groove geometry on microstructure, mechanical behaviour, residual stresses and distortion of Alloy 617/P92 steel dissimilar metal weld (DMW) joints. Manual multi-pass tungsten inert gas welding with ERNiCrCoMo-1 filler was employed to fabricate the DMW for two different groove designs: Narrow V groove (NVG) and Double V groove (NVG). The microstructural examination suggested a heterogeneous microstructure evolution at the interface of the P92 steel and ERNiCrCoMo-1 weld, including the macrosegregation and element diffusion near the interface. The interface structure included the beach parallel to the fusion boundary at the P92 steel side, the peninsula connected to the fusion boundary and the island within the weld metal and partially melted zone along Alloy 617 fusion boundary. An uneven distribution of beach, peninsula and island structures along the fusion boundary of P92 steel was confirmed from optical and SEM images of interfaces. The major diffusion of the Fe from P92 steel to ERNiCrCoMo-1 weld and Cr, Co, Mo, and Ni from ERNiCrCoMo-1 weld to P92 steel were witnessed from SEM/EDS and EMPA map. The Mo-rich M6C and Cr-rich M23C6 phases were detected in inter-dendritic areas of the weld metal using the weld’s SEM/EDS, XRD and EPMA study, which formed due to the rejection of Mo from the core to inter-dendritic locations during solidification. The other phases detected in the ERNiCrCoMo-1 weld were Ni3(Al, Ti), Ti(C, N), Cr7C3 and Mo2C. A variation in the microstructure of weld metal from top to root and also along the transverse direction in terms of composition and dendritic structure and also due to the composition gradient between dendrite core and inter-dendritic areas, a significant variation in hardness of weld metal was observed from both top to root and also in the transverse direction. The peak hardness was measured in CGHAZ of P92 while the minimum was in ICHAZ of P92 steel. Tensile test studies of both NVG and DVG welds joint demonstrated that failure occurred at P92 steel in both, room-temperature and high-temperature tensile tests and ensured the welded joint’s applicability for advanced ultra-supercritical applications. However, the strength of the welded joint for both types of joints was measured as lower than the strength of the base metals. In Charpy impact testing of NVG and DVG welded joints, specimens failed in two parts with a small amount of plastic deformation and impact energy of 99 ± 4 J for the NVG welds joint and 91 ± 3 J for the DVG welded joint. The welded joint met the criteria for boiler applications in terms of impact energy (minimum 42 J as per European Standard EN ISO15614-1:2017 and 80 J as per fast breeder reactor application). In terms of microstructural and mechanical properties, both welded joints are acceptable. However, the DVG welded joint showed minimum distortion and residual stresses compared to the NVG welded joint.

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Section: Introductionmentioning

confidence: 99%

Structural integrity assessment of Inconel 617/P92 steel dissimilar welds for different groove geometry

Kumar

Pandey

2023

Sci Rep

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“…When using dissimilar materials for surfacing welding, nickel-based welding materials [3] with high nickel content in the weld could be employed. It was found that in this way the weld's toughness would be enhanced and the likelihood of cracking would be reduced, which while also eliminated the needing for heat treatment and facilitated easier on-site operation control.…”

Section: Welding Repair Of the Lace Convex Tablementioning

confidence: 99%

Fracture Analysis and Repair of Last Stage Blade Reinforcement Boss for Low Pressure Cylinder Rotor of 330 MW Unit

Chen

2024

ACETR

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The lace convex table of the final stage blade of a 330 MW turbine fractured. The reason was analyzed by fracture analysis, chemical composition analysis and metallographic analysis. It showed that the overload was the main reason for the fracture. Deformation of guide ring caused by fracture of guide ring bolt was the main reason of the overload. The analysis of the guide ring bolt showed that the brittleness of the guide ring bolt was the main reason for its fracture. It was suggested to strengthen the supervision of the manufacturing process of the guide ring bolt. The lace convex table was repaired by surfacing welding. A reasonable welding process was developed and the repair was successful. Abstract, Final stage blade, Lace convex table, Surfacing welding, Welding repair

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“…Besides, welding is a lightweight design method facilitating the manufacturing of larger steam turbine rotors. Multi-layer and multi-pass narrow-gap submerged arc welding (NG-SAW) technologies are used for the manufacturing of large and thick-walled steam turbine welded rotors due to their advantages in terms of good reliability combined with low residual stress and high deposition efficiency [5][6][7]. Buttering layer welding technology is also employed in the manufacturing of dissimilar metal welded rotors to alleviate the chemical composition and property differences between dissimilar base metals and weld metals [8,9].…”

Section: Introductionmentioning

confidence: 99%

Fracture Toughness of Different Region Materials from a Dissimilar Metal Welded Joint in Steam Turbine Rotor

Wang

2022

Coatings

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This study systematically evaluated the fracture toughness of a CrMoV/NiCrMoV dissimilar metal welded joint (DMWJ) with buttering layer technology in a steam turbine rotor . The fracture resistance curves and parameters of base metals (BM-1 and BM-2), weld metal (WM), buttering layer (BL), and heat-affected zones (HAZ-1 and HAZ-2) in the welded joint were all obtained. The characteristic microstructures, carbides, and fracture surfaces were observed by optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results revealed a different fracture toughness of each region in the DMWJ. The BM-1 showed a brittle fracture mode, mainly related to the directional needle-shaped carbide M3C. However, HAZ-1, BL, WM, HAZ-2, and BM-2 illustrated ductile fracture mode. The tempered microstructure and dispersed carbides increased the toughness of each material. Except for BM-1, the ductile fracture toughnesses of BL and WM were low in DMWJ due to coarse spherical carbide M7C3. The fracture toughness in the middle of HAZs was higher than that of the corresponding BMs owing to the fine tempered martensite and bainite. The fracture toughness along DMWJ appeared uneven. In sum, these findings look promising for the accurate integrity evaluation of DMWJs.

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Welding technologies for ultra-supercritical power plant materials

Cited by 13 publications

References 9 publications

Structural integrity assessment of Inconel 617/P92 steel dissimilar welds for different groove geometry

Structural integrity assessment of Inconel 617/P92 steel dissimilar welds for different groove geometry

Fracture Analysis and Repair of Last Stage Blade Reinforcement Boss for Low Pressure Cylinder Rotor of 330 MW Unit

Fracture Toughness of Different Region Materials from a Dissimilar Metal Welded Joint in Steam Turbine Rotor

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