Effect of mechanical mismatch on fracture mechanical behavior of SA 508 – Alloy 52 narrow gap dissimilar metal weld

Sarikka, Teemu; Ahonen, Matias; Mouginot, Roman; Nevasmaa, Pekka; Karjalainen-Roikonen, Päivi; Ehrnstén, Ulla; Hänninen, Hannu

doi:10.1016/j.ijpvp.2017.08.003

Cited by 26 publications

(12 citation statements)

References 17 publications

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“…For the effect of the material constraints, the J-resistance curves [5][6][7][8][9][10], crack growth paths [11,12], fracture toughness [13][14][15], and stress and strain fields at crack tip [16][17][18][19][20] under different material constraints have been widely studied. Wang et al [5,6] studied the J-resistance curves of a dissimilar metal welded joint at different crack positions with different material constraints.…”

Section: Introductionmentioning

confidence: 99%

“…Fan et al [7][8][9] studied the J-resistance curves of the bi-material welded joint under different work hardening mismatches. Sarikka et al [10] studied the effect of mechanical mismatch on the J-resistance curves of SA508-Alloy52 narrow gap dissimilar metal weld. Samal et al [11] investigated the altering of the crack growth path in the bi-material interface region under different material constraints.…”

Section: Introductionmentioning

confidence: 99%

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Effect Range of the Material Constraint-II. Interface Crack

Dai

Yang

Wang

2019

Metals

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The selection of fracture behaviors used in the structure integrity assessment has significant implications on the accuracy of the assessment. The effect range of the material constraint is an important factor which effects the fracture behaviors of structures and exists in the different kinds of welded joints with the center crack. However, for the material constraint induced by an interface crack, which also appears widely in the welded joints, it is not clear whether the effect range exists or not. The further study of the effect range of the material constraint for the welded joints with interface crack is meaningful. Thus, in this study, different basic models with interface crack were designed, the fracture behaviors of these basic models under different material constraints were calculated, and the effect range of the material constraint induced by interface crack were studied. This study about the interface crack and the previous study about the center crack provide an additional basis for an accurate structure integrity assessment.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect Range of the Material Constraint-II. Interface Crack

Dai

Yang

Wang

2019

Metals

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“…In the case of SINI PWHT specimens, cracks in J-R tests initiated in LAS close to the FB and tended to propagate only along the soft LAS CDZ. On the contrary, in SINI AW specimens, cracks in J-R tests were occasionally deflected over the FB into the weld metal and back into the LAS, forming a serrated fracture surface [21,36,37]. A serrated type of fracture forms a larger surface area, which requires more energy than the formation of a planar fracture surface with a smaller surface area.…”

Section: Niwel Hv It (15 Mn) Location Distance Of Peak Hardness Frommentioning

confidence: 99%

“…The thermal ageing at 400 • C for 5000 and 10,000 h is therefore considered to be slightly beneficial in the case of the RPV safe-end Alloy 52 narrow-gap DMW, when considering the performance of the DMW in the operation environment (high-temperature PWR water), as it reduces the strength mismatch at the weld interface. It has been shown that thermal ageing has a detrimental effect on impact toughness of the narrow-gap DMW LAS HAZ, but the ductile-to-brittle transition temperature after thermal ageing remains low enough to ensure the safe operation and shut-down of the power plant [37][38][39][40].…”

Section: Niwel Hv It (15 Mn) Location Distance Of Peak Hardness Frommentioning

confidence: 99%

Effect of Thermal Ageing at 400 °C on the Microstructure of Ferrite-Austenite Interface of Nickel-Base Alloy Narrow-Gap Dissimilar Metal Weld

Ahonen

Mouginot

Sarikka

et al. 2020

Metals

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Dissimilar metal welds (DMWs) are a key design feature in nuclear power systems, typically involving ferritic low-alloy steels (LAS), stainless steels (SS), and nickel-base alloys. They are, however, a potential concern regarding the structural integrity of nuclear power systems. In particular, the LAS/nickel-base alloy weld metal interface is known to develop a local strength mismatch upon post-weld heat treatment (PWHT). Very limited data is available on the effect of thermal ageing on the DMW interface. The aim of this study was to investigate the effects of thermal ageing at 400 °C for up to 10,000 h on a narrow-gap DMW mock-up representative of the weld between the reactor pressure vessel nozzle and its safe-end after PWHT, with a special focus on the LAS SA 508/nickel-base Alloy 52 weld metal interface. No significant effect of thermal ageing on the appearing microstructure was observed in either LAS base material, LAS heat-affected zone or Alloy 52 weld metal. However, thermal ageing reduced the local strength mismatch at the LAS/nickel-base weld metal interface formed during PWHT. The reduction of the strength mismatch was detected using nanoindentation measurements and was concluded to be associated with a decrease in the carbon pile-up in the weld metal caused by PWHT. Based on the obtained results, thermal ageing promotes carbon diffusion from the weld metal side of the fusion boundary further away into the weld metal and thus slightly decreases the local strength mismatch.

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“…The Claudio Ruggieri group examined the effect of weld strength mismatch and crack sizes (a/W ratios) on J and CTOD ductile fracture parameters while using SENT specimens based on plastic η-factors and load separation analysis [19,20]. On the other hand, the similar investigation about strength mismatch effect on fracture mechanical behavior for SA 508-Alloy 52 narrow gap dissimilar metal weld was conducted by microstructural and fracture resistance characterizations [21]. The results showed that the mismatch state caused the crack to propagate towards the fusion boundary.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Strength Mismatch Effect on Ductile Crack Growth Resistance in Welding Pipe

Song

et al. 2020

Applied Sciences

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The effect of strength mismatch (ratio between the yield stress of weld metal and base metal, M y ) on the ductile crack growth resistance of welding pipe was numerically analyzed. The ductile fracture behavior of welding pipe was determined while using the single edge notched bending (SENB) and single edge notched tension (SENT) specimens, as well as axisymmetric models of circumferentially cracked pipes for comparison. Crack growth resistance curves (as denoted by crack tip opening displacement-resistance (CTOD-R curve) have been computed using the complete Gurson model. A so-called CTOD-Q-M formulation was proposed to calculate the weld mismatch constraint M. It has been shown that the fracture resistance curves significantly increase with the increase of the mismatch ratio. As for SENT and pipe, the larger M y causes the lower mismatch constraint M, which leads to the higher fracture toughness and crack growth resistance curves. When compared with the standard SENB, the SENT specimen and the cracked pipe have a more similar fracture resistance behavior. The results present grounds for justification of usage of SENT specimens in fracture assessment of welding cracked pipes as an alternative to the traditional conservative SENB specimens.

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Effect of mechanical mismatch on fracture mechanical behavior of SA 508 – Alloy 52 narrow gap dissimilar metal weld

Cited by 26 publications

References 17 publications

Effect Range of the Material Constraint-II. Interface Crack

Effect Range of the Material Constraint-II. Interface Crack

Effect of Thermal Ageing at 400 °C on the Microstructure of Ferrite-Austenite Interface of Nickel-Base Alloy Narrow-Gap Dissimilar Metal Weld

Numerical Investigation of Strength Mismatch Effect on Ductile Crack Growth Resistance in Welding Pipe

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