Global mechanical tensioning for the management of residual stresses in welds

Richards, David; Prangnell, P.B.; Williams, Stewart; Withers, Philip J.

doi:10.1016/j.msea.2007.12.042

Cited by 90 publications

(84 citation statements)

References 28 publications

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“…The power was distributed in each case in proportion to the surface velocity. For the probe, the shoulder power was increased in proportion to the radius across the ring source surface (as described by Richards et al, 2008). Standard values of thermal conductivity were used for the AA7050 alloy plate.…”

Section: Modellingmentioning

confidence: 99%

Stationary shoulder FSW for joining high strength aluminum alloys

Chen

Strong

et al. 2015

Journal of Materials Processing Technology

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The new process of 'Stationary Shoulder' Friction Stir Welding (SSFSW) has been directly compared to conventional (Friction Stir Welding) using welds produced in a high strength AA7050-T7651 aluminium aerospace alloy. The process window for each approach was first compared using torque -rotation rate decay curves. Under optimum process conditions, SSFSW had a ~ 30% lower heat input than FSW and the stationary shoulder resulted in narrower welds with a reduced heat affected zone (HAZ) width. The SSFSW welds also had more uniform through thickness properties and performed better than conventional FSWs in cross-weld tensile tests. In addition it is demonstrated that SSFSW process resulted in a far superior surface finish, although the stationary shoulder lead to surface 'speed cracking' under certain welding conditions. The reasons for these benefits are discussed aided by thermal and hardness modelling.

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Section: Modellingmentioning

confidence: 99%

Stationary shoulder FSW for joining high strength aluminum alloys

Chen

Strong

et al. 2015

Journal of Materials Processing Technology

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“…However, the actual magnitude depends on the thermal field and the properties of the material, specifically its straintemperature and yield stress-temperature relationships [12]. For example, in aluminium alloy welds the development of tensile stresses at the weld interface is normally limited by the low elevatedtemperature yield stress and low post-weld hardness compared with the parent metal (see Figure 3), resulting in a characteristic 'M-shaped' tensile stress profile [13,14]. However, in fusion welds the total size of the tensile region is typically larger than the extent of the melted zone (Figure 3), corresponding instead to the extent of plastic deformation induced by thermal stress.…”

Section: Formation Of Residual Stresses During Weldingmentioning

confidence: 99%

“…The mechanism by which this reduces the residual stress is summarised by Richards et al [13,119]. Essentially, the magnitude of the tensile longitudinal stress which can exist at the weld is always limited by the yield strength of the weld material.…”

Section: Global Mechanical Tensioningmentioning

confidence: 99%

Contemporary approaches to reducing weld induced residual stress

Coules

2013

Materials Science and Technology

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. AbstractSelf-equilibrating residual stresses may occur in materials in the absence of external loading due to internal strain inhomogeneity. While favourable distributions of residual stress can bestow an object with the appearance of superior material properties, most welding processes leave behind residual stresses in particularly unfavourable patterns, causing a greater susceptibility to fracture-based failure mechanisms and unintended deformation. Currently, heat treatment is the primary means of removing these stresses, but since the formation of residual stress is dependent upon many material and process factors, there are several other viable mechanisms (using thermal, mechanical or phase transformation effects) by which it may be modified. It is only now, using relevant advances in numerical and experimental methods, that these techniques are being fully explored. This article gives a brief introduction to weld-induced residual stresses and reviews the current state-of-the-art with regard to their reduction. Emphasis is placed on the recent development of unconventional techniques, and the mechanisms by which they act.

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“…These include post-weld heat treatment (Ref 6), shot peening, modification of the structural configurations, and the implementation of thermal tensioning techniques (Ref 7,8). It has also been reported that application of cold rolling is capable not only of removing the residual stress but depending on its magnitude it may also form beneficial compressive stress state .…”

Section: Introductionmentioning

confidence: 99%

Stress Engineering of Multi-pass Welds of Structural Steel to Enhance Structural Integrity

Ganguly

Sule

Yakubu³

2016

J. of Materi Eng and Perform

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In multi-pass welding, the weld metal and the associated heat-affected zone are subjected to repeated thermal cycling from successive deposition of filler metals. The thermal straining results into multi-mode deformation of the weld metal which causes a variably distributed residual stress field through the thickness and across the weld of a multi-pass weldment. In addition to this, the as-welded fusion zone microstructure shows dendritic formation of grains and segregation of alloying element. This may result in formation of micro-corrosion cells and the problem would aggravate in case of highly alloyed materials. Local mechanical tensioning is an effective way of elimination of the weld tensile residual stress. It has been shown that application of cold rolling is capable not only of removing the residual stress, but depending on its magnitude it may also form beneficial compressive stress state. Multi-pass structural steel welds used as structural alloy in general engineering and structural applications. Such alloys are subjected to severe inservice degradation mechanisms e.g., corrosion and stress corrosion cracking. Welds and the locked-in residual stress in the welded area often initiate the defect which finally results in failure. In the present study, a multi-pass structural steel weld metal was first subjected to post-weld cold rolling which was followed by controlled heating by a fiber laser. Cold straining resulted in redistribution of the internal stress through the thickness and controlled laser processing helps in reforming of the grain structure. However, even with controlled laser, processing the residual stress is reinstated. Therefore, a strategy has been adopted to roll the metal post-laser processing so as to obtain a complete stress-free and recrystallized microstructure.

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Global mechanical tensioning for the management of residual stresses in welds

Cited by 90 publications

References 28 publications

Stationary shoulder FSW for joining high strength aluminum alloys

Stationary shoulder FSW for joining high strength aluminum alloys

Contemporary approaches to reducing weld induced residual stress

Stress Engineering of Multi-pass Welds of Structural Steel to Enhance Structural Integrity

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