Residual stresses in welded joints in 1460 aluminium alloy

Recent discoveries of stress corrosion cracking (SCC) at nickel-based metals in pressurized water reactors (PWRs) and boiling water reactors (BWRs) have raised concerns about safety and integrity of plant components. It has been recognized that welding residual stress is an important factor causing the issue of SCC in a weldment. In this study, both numerical simulation technology and experimental method were employed to investigate the characteristics of welding residual stress distribution in several typical welded joints, which are used in nuclear power plants. These joints include a thick plate butt-welded Alloy 600 joint, a dissimilar metal J-groove set-in joint and a dissimilar metal girth-butt joint. First of all, numerical simulation technology was used to predict welding residual stresses in these three joints, and the influence of heat source model on welding residual stress was examined. Meanwhile, the influence of other thermal processes such as cladding, buttering and heat treatment on the final residual stresses in the dissimilar metal girth-butt joint was also clarified. Secondly, we also measured the residual stresses in three corresponding mock-ups. Finally, the comparisons of the simulation results and the measured data have shed light on how to effectively simulate welding residual stress in these typical joints.

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The effect of weld geometry and residual stresses on the fatigue of welded joints under combined loading

Journal of Materials Processing Technology ◽

10.1016/s0924-0136(97)00418-4 ◽

1998 ◽

Vol 77 (1-3) ◽

pp. 201-208 ◽

Cited By ~ 54

Author(s):

T.Ninh Nguyen ◽

M.A. Wahab

Keyword(s):

Residual Stresses ◽

Welded Joints ◽

Combined Loading ◽

Weld Geometry

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Surface Modification Analysis after Shot Peening of AA 7075 in Different States

Materials Science Forum ◽

10.4028/www.scientific.net/msf.768-769.519 ◽

2013 ◽

Vol 768-769 ◽

pp. 519-525 ◽

Cited By ~ 1

Author(s):

Sebastjan Žagar ◽

Janez Grum

Keyword(s):

Residual Stress ◽

Surface Layer ◽

Residual Stresses ◽

Aluminium Alloy ◽

Shot Peening ◽

Fatigue Testing ◽

Stress Profile ◽

Treatment Conditions ◽

Stress Profiles ◽

Compressive Residual Stresses

The paper deals with the effect of different shot peening (SP) treatment conditions on the ENAW 7075-T651 aluminium alloy. Suitable residual stress profile increases the applicability and life cycle of mechanical parts, treated by shot peening. The objective of the research was to establish the optimal parameters of the shot peening treatment of the aluminium alloy in different precipitation hardened states with regard to residual stress profiles in dynamic loading. Main deformations and main residual stresses were calculated on the basis of electrical resistance. The resulting residual stress profiles reveal that stresses throughout the thin surface layer of all shot peened specimens are of compressive nature. The differences can be observed in the depth of shot peening and the profile of compressive residual stresses. Under all treatment conditions, the obtained maximum value of compressive residual stress ranges between -200 MPa and -300 MPa at a depth between 250 μm and 300 μm. Comparison of different temperature-hardened aluminium alloys shows that changes in the Almen intensity values have greater effect than coverage in the depth and profile of compressive residual stresses. Positive stress ratio of R=0.1 was selected. Wöhler curves were determined in the areas of maximum bending loads between 30 - 65 % of material's tensile strength, measured at thinner cross-sections of individual specimens. The results of material fatigue testing differ from the level of shot peening on the surface layer.

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A Study of the Influence of Local Heat Treatment on the Structure of Welded Titanium Pipelines

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.410.37 ◽

2021 ◽

Vol 410 ◽

pp. 37-41

Author(s):

Natalia A. Astafeva ◽

Andrey A. Balanovskiy ◽

Anna A. Pershina

Keyword(s):

Heat Treatment ◽

Residual Stresses ◽

Titanium Alloys ◽

Welded Joints ◽

Treatment Method ◽

Local Heat ◽

Optical Metallography ◽

Heat Treated ◽

Weld Structure ◽

Heat Treatment Method

The article analyzes the results of a study of the influence of zonal heat treatment on the structure of welded joints of pipeline elements made of titanium alloys Ti-3.5Al-1.5Mn. In the manufacture of such structures, the TIG welding method is used to join pipe elements, after which the heat treatment method can be used to relieve residual stresses. The experiments have confirmed the effectiveness of zonal heat treatment preceded by welding. It was revealed that for welded joints made of titanium alloys, heat treatment can stabilize the structure. In experiments conducted by the method of optical metallography, the structure of heat treated and untreated welded joints was investigated. The influence of heat treatment on the weld structure and heat-affected zone was identified.

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