PWSCC of Nickel Base Alloys in Vapor Phase Environment of Pressurizer

Tsuruta, Takao; Satô, Kenji; Asada, Seiji; Kobayashi, Takaaki; Okimura, Koji; Matsubara, Nariyasu

doi:10.1115/icone16-48377

Cited by 4 publications

(2 citation statements)

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“…31 In the welded joints (dissimilar metal region) of LWRs, where the temperature is high, different defects may occur due to the particularity of the welding technology such as pores, cracks, inclusions, impermeability, composition gradients, inevitable residual stresses, and variations in the mechanical properties. [32][33] Cold bending is used mainly to manufacture the pipe used in LWRs. Different degrees of work hardening occurs due to an increase in the thickness of the pipe.…”

Section: Methodsmentioning

confidence: 99%

Effect of Material Macrostructural Parameters on Quantitative Stress Corrosion Cracking Plastic Zone Using Extended Finite Element Method in Welded Joints for Light Water Reactor Environment

et al. 2020

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Alloy 600, a nickel-chromium alloy, has an outstanding corrosion resistance with excellent fabricability and is used in light water reactors(LWRs) at elevated temperatures. The alloy is also being considered for an advanced reactor concept because of its high allowable design strength at the elevated temperature. The Alloy 600 is a power hardening material and basic plastic properties of the alloy are changed in the welded zone due to inhomogeneity in weld joints. The extended finite element method(XFEM) is used in which the problem of variations invariably in the stress intensity factors, K, at a different instant rate exists. This paper focuses on the effect of variations in macrostructural properties of the alloy on stress corrosion cracking(SCC) plastic zone ahead of crack-tip using XFEM.To control the variations in the K, a new technique is also introduced in this research. The results show that the plastic zone is affected by K(increases with the increase of K), yield strength(plastic zone decreases with the increase in yield strength), and hardening exponent ânâ(core region increases with the increase of exponent) of the materials. Simulations are carried in ABAQUS 6.14 and results are compared with experimental data.

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Section: Methodsmentioning

confidence: 99%

Effect of Material Macrostructural Parameters on Quantitative Stress Corrosion Cracking Plastic Zone Using Extended Finite Element Method in Welded Joints for Light Water Reactor Environment

et al. 2020

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“…Recently stress corrosion cracks were found in dissimilar metal welds of some pressurized water reactor (PWR) nuclear plants 1–5 . As a result, several mitigation methods have been discussed, 5–7 one of which is the weld overlay 5,8–10 .…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on welding residual stresses in a PWR pressurizer safety/relief nozzle

Song

Bae

Kim

et al. 2010

Fatigue Fract Eng Mat Struct

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A B S T R A C T This paper presents finite element simulation results of residual stresses in dissimilar metal welds of a PWR pressurizer safety/relief nozzle. The present results are believed to be significant in two aspects. The first one is to consider the effect of the presence of similar metal welds on resulting residual stresses. The second one is the mitigation effect of the overlay welding thickness on residual stresses. After dissimilar metal welding, tensile residual stresses are present both at the inner surface and at the outer surface of dissimilar metal welds. Adjacent similar metal welding, however, decreases residual stresses to compressive ones at the inner surface of dissimilar metal welds, possibly due to the bending mechanism caused radial contraction of the weld. At the outer surface of dissimilar metal welds, similar metal welding increases residual stresses. Overlay welding further decreases residual stresses at the inner surface of dissimilar and similar metal welds, but increases slightly residual stresses at the outer surface.Keywords finite element simulation; PWR pressurizer safety/relief nozzle; weld overlay; welding residual stress. I N T R O D U C T I O NRecently stress corrosion cracks were found in dissimilar metal welds of some pressurized water reactor (PWR) nuclear plants. [1][2][3][4][5] As a result, several mitigation methods have been discussed, 5-7 one of which is the weld overlay. 5,8-10 As the weld overlay method has been applied to piping systems in boiling water reactor components over some decades, 11,12 its effectiveness in mitigation is well appreciated. In addition, the weld overlay can also provide other benefits, for instance, improved inspectability and structural reinforcement effects due to an increasing thickness. 5,10,12 Although some guidelines on the weld overlay for dissimilar metal welds in pressurized water reactor nuclear plants are available, 13-15 numerical simulations are desirable to assess the weld overlay effect on residual stresses, as the weld overlay process is expensive. Furthermore such numerical simulations can be used to help optimise the weld overlay process.Welding residual stress simulation of stainless pipes using the finite element (FE) analysis is relatively well established, and accordingly many papers have been published Correspondence: Yun-Jae Kim.in the literature. [16][17][18][19][20] Some relevant works are briefly described here. Brickstad and Josefson 16 performed a parametric study for multipass circumferential butt-welding of stainless steel pipes to quantify residual stresses and their sensitivity to variation in weld parameters. Yaghi et al. 17 presented another parametric study on effects of the thickness and radius-to-thickness ratio on residual stresses in butt-welded stainless pipes. Related to repair welds and overlay welding for dissimilar metal welds in PWR plants, many works have been published in American Society of Mechanical Engineers, Pressure Vessel and Piping Division (ASME PVP) conferences. [4][5][6]8,9 One ...

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The safe-end length effect on welding residual stresses in dissimilar metal welds of surge nozzles

Song

Kim

et al. 2011

Engineering Fracture Mechanics

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PWSCC of Nickel Base Alloys in Vapor Phase Environment of Pressurizer

Cited by 4 publications

References 0 publications

Effect of Material Macrostructural Parameters on Quantitative Stress Corrosion Cracking Plastic Zone Using Extended Finite Element Method in Welded Joints for Light Water Reactor Environment

Effect of Material Macrostructural Parameters on Quantitative Stress Corrosion Cracking Plastic Zone Using Extended Finite Element Method in Welded Joints for Light Water Reactor Environment

Numerical investigation on welding residual stresses in a PWR pressurizer safety/relief nozzle

The safe-end length effect on welding residual stresses in dissimilar metal welds of surge nozzles

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