Transition of creep damage region in dissimilar welds between Inconel 740H Ni-based superalloy and P92 ferritic/martensitic steel

Shin, Kee Sam; Lee, Jiwon; Han, Jung-Min; Lee, Kyong-Woon; Kong, Byeong-Ook; Hocheng, H.

doi:10.1016/j.matchar.2018.02.039

Cited by 67 publications

(16 citation statements)

References 29 publications

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“…The detailed observation revealed that the macroscopically classified interfacial failure (Figure 11c) did not occur directly at the T92 BM/Ni WM interface but the fracture ran partly through T92 BM and largely through precipitation-depleted zone (PDZ) of Ni WM located at a distance of about 5-8 µm from the fusion boundary (see Figure 14a,b). The occurrence of PDZ in Ni WM can presumably be related to specific welding metallurgy phenomena such as weld metal dilution, the presence of unmixed or partially melted zone, and/or type II boundaries formation [4,13,[31][32][33][34][35].…”

Section: Ageing Effects On Fracture Behavior In Relation To Microstrumentioning

confidence: 99%

Ageing Effects on Room-Temperature Tensile Properties and Fracture Behavior of Quenched and Tempered T92/TP316H Dissimilar Welded Joints with Ni-Based Weld Metal

Čiripová

Falat

Ševc

et al. 2018

Metals

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The present work is focused on the investigation of isothermal ageing effects on room-temperature tensile properties and the failure of quenched and tempered martensitic/austenitic weldments between T92 and TP316H heat-resistant steels. The dissimilar weldments were produced by gas tungsten arc welding technique using a Ni-based Thermanit Nicro 82 filler metal. The welded joints were subjected to unconventional post-welding heat treatment consisting of the welds solutionizing (1060 °C/30 min), followed by their water quenching and final stabilization tempering (760 °C/60 min). The treatment was completed by spontaneous air cooling within a tempering furnace. The welds in their initial quenched and tempered condition were subsequently aged at 620 °C for up to 2500 h. Apart from room-temperature tensile tests performed for all the welds material states, additional cross-weld hardness measurements were carried out on longitudinal sections of broken tensile specimens. The applied thermal exposure resulted in recognizable deterioration of plastic properties, whereas their effects on strength properties were rather small. The welds tensile straining and fracture evolution exhibited competitive behavior between the austenitic TP316H region and Ni-based weld metal. The observed failure locations showed significant hardness peaks due to intensive, necking-related strain hardening effects occurred during the tensile tests.

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Section: Ageing Effects On Fracture Behavior In Relation To Microstrumentioning

confidence: 99%

Ageing Effects on Room-Temperature Tensile Properties and Fracture Behavior of Quenched and Tempered T92/TP316H Dissimilar Welded Joints with Ni-Based Weld Metal

Čiripová

Falat

Ševc

et al. 2018

Metals

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“…4 shows the microstructure of FGHAZ in P92 welds produced by shielded metal arc welding (SMAW) process. Shin et al 26) reported that PAG size within the FGHAZ was much smaller (∼10 μm), compared to the base metal (∼25 μm). In their work, few precipitates were observed at the fine PAG boundary, while a lot of large carbides were distributed at the ghost PAG boundary ( Fig.…”

Section: Microstructure Characteristics Of Rafm Steel Weld and Type Imentioning

confidence: 99%

“…Tsukamoto et al 28) addressed this observation. They investigated systematically the cause of type IV failure, and claimed that lack of precipitation strengthening at PAG and block boundaries of FGHAZ is the most dominant factor to cause type IV failure 26,28,29) .…”

Section: Microstructure Characteristics Of Rafm Steel Weld and Type Imentioning

confidence: 99%

“…Many studies have been made to elucidate the cause of type IV failure: grain refinement of FGHAZ 32) , HAZ softening and coarsening of M 23 C 6 33,34) , the formation of Laves phase 31) and distribution of precipitates 28,29) were proposed. Recently, Tsukamoto et al 28) , Abe ,29) and Shin et al 26) claimed that lack of precipitation strengthening at PAG and block boundaries of FGHAZ could be the most dominant factor to cause type IV failure. As shown in Figs.…”

Section: Microstructure Characteristics Of Rafm Steel Weld and Type Imentioning

confidence: 99%

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Technical Issues in Fusion Welding of Reduced Activation Ferritic/Martensitic Steels for Nuclear Fusion Reactors

Jun

Moon

et al. 2020

Journal of Welding and Joining

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Reduced activation ferritic/martensitic steels (RAFMs), which are the modified variants of 9Cr-1Mo heat resisting steels, have been recognized as candidate structural materials for the blanket module of nuclear fusion reactors. Since the blanket is exposed to a high flux of neutrons and complex periods of fluctuating mechanical and thermal stresses, evaluation of the high-temperature mechanical properties of both the RAFM steel and welds, and understanding of their degradation behaviors, are needed to provide feedback for the development of better RAFM steels and welding processes. In this review article, first, several welding processes used to fabricate the blanket modules are introduced. Microstructural evolution during fusion welding of the RAFM steel and its subsequent degradation during creep and/or irradiation are reviewed. The thermal stability of the RAFM steel originates from solid solution strengthening, sub-grain hardening and precipitation hardening. The degradation of the RAFM steel is discussed in terms of matrix recovery associated with lath widening and reduction of dislocation density, coarsening of precipitates and the formation of Laves and Z phases. This work helps provide insight on how to mitigate the microstructural degradation, and design optimal welding technology.

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“…Because of rapid heating and cooling during welding, non-equilibrium microstructures were formed in heat affected zone (HAZ) [8,9], leading to the degradation of mechanical properties of HAZ and thus weakening the whole welded joint [10]. For the martensitic steel welded joint used in thermal power unit, the service life mainly depended on its creep performance and type IV crack in HAZ was a common creep fracture mode which led to premature failure of the welded joint [11][12][13][14][15][16][17][18][19][20][21]. As they moved away from fusion line, the sub-zones of HAZ of conventional martensitic heat resistant steel, i.e., P91, were classified into coarse-grained HAZ (CGHAZ, also known as overheated sub-zone of HAZ), fine grained HAZ (FGHAZ, also known as normalized sub-zone of HAZ), inter-critical HAZ (ICHAZ) and over-tempered base metal (OTBM), which were distinguished with the different peak temperature and prior austenite grain size [22], as shown in Figure 1 [23].…”

Section: Introductionmentioning

confidence: 99%

A Review of Austenite Memory Effect in HAZ of B Containing 9% Cr Martensitic Heat Resistant Steel

Cai

et al. 2019

Metals

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During the welding process of B containing 9% Cr martensitic heat resistant steel (9Cr-B steel), austenite memory effect (referred to that the prior austenite grains in the heat affected zone (HAZ) after welding inherit the shape and size of prior austenite grains before welding) occurs in its normalized sub-zone of HAZ and the grain refinement is suppressed, which can effectively prevent type IV crack, and improve the service life of the welded joint at high temperatures. In the present article, α/γ reverse transformation behavior in the normalized sub-zone of 9Cr-B steel HAZ is reviewed. Austenite memory effect of 9Cr-B steel is derived from B addition. The main mechanisms of austenite memory effect during α/γ reverse transformation are discussed. Various models of boron causing austenite memory effect are discussed in detail. Matrix microstructure also plays an important role in austenite memory effect. Effects of heating rate, peak temperature, and holding time at peak temperature on austenite memory effect are also discussed.

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Transition of creep damage region in dissimilar welds between Inconel 740H Ni-based superalloy and P92 ferritic/martensitic steel

Cited by 67 publications

References 29 publications

Ageing Effects on Room-Temperature Tensile Properties and Fracture Behavior of Quenched and Tempered T92/TP316H Dissimilar Welded Joints with Ni-Based Weld Metal

Ageing Effects on Room-Temperature Tensile Properties and Fracture Behavior of Quenched and Tempered T92/TP316H Dissimilar Welded Joints with Ni-Based Weld Metal

Technical Issues in Fusion Welding of Reduced Activation Ferritic/Martensitic Steels for Nuclear Fusion Reactors

A Review of Austenite Memory Effect in HAZ of B Containing 9% Cr Martensitic Heat Resistant Steel

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