Probing residual stresses in stationary shoulder friction stir welding process

Vicharapu, Buchibabu; Liu, H.; Fujii, Hidetoshi; Narasaki, Kunio; Ma, Ninshu; De, A.

doi:10.1007/s00170-019-04570-9

Cited by 24 publications

(18 citation statements)

References 37 publications

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“…It is well-known that tensile welding residual stress is detrimental to the fatigue strength of welded joint [28,29]. To minimize the unfavorable tensile stress, the low transformation temperature (LTT) alloys, which take advantage of martensitic transformation, have been developed during the past two decades [30][31][32].…”

Section: Thermal Cycles In Elongated Weld With Low Transformation Temmentioning

confidence: 99%

Efficient analysis of welding thermal conduction using the Newton–Raphson method, implicit method, and their combination

Feng

et al. 2020

Int J Adv Manuf Technol

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Finite element analysis is commonly used to investigate the thermal-mechanical phenomena during welding. To improve the computing efficiency of finite element analysis for welding thermal conduction, a novel Newton-Raphson method (NRM) without the computation of inverse matrix and a hybrid method combing the NRM and conventional implicit method (IMP) were developed. Comparison of computing time between the hybrid method implemented in an in-house software JWRIAN and the IMP used in a commercial software ABAQUS indicated that the computing speed of the former was about 4.5 times faster than that of the latter. Additionally, compared to the conventional IMP, the NRM exhibited higher computing efficiency in the analysis of transient thermal conduction during the welding heating process. Meanwhile, a combined hybrid method of the NRM and IMP was verified to be more efficient in analyzing the welding thermal conduction throughout the heating and cooling processes. Moreover, the thermal cycles computed by the hybrid method were consistent with those from experimental measurement, indicating the high accuracy of the hybrid method. Furthermore, the hybrid method was used to predict the temperature field of the corner boxing fillet joint welded by a low transformation temperature weld metal for generation of compressive residual stress.

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Section: Thermal Cycles In Elongated Weld With Low Transformation Temmentioning

confidence: 99%

Efficient analysis of welding thermal conduction using the Newton–Raphson method, implicit method, and their combination

Feng

et al. 2020

Int J Adv Manuf Technol

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“…A steady state three-dimensional heat conduction analysis was undertaken to estimate the temperature field following the governing equation as [30,31] (Equation 1).…”

Section: Numerical Modellingmentioning

confidence: 99%

“…Ai and Vi refer to the area and volume of the shear layer around the tool probe. The terms δ and µ f refer to the local variations in fractional sliding and co-efficient of friction along the tool -workpiece interface and are estimated as [30][31][32][33] (Equation 3 and 4).…”

Section: Numerical Modellingmentioning

confidence: 99%

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Probing underlying mechanisms for PCBN tool decay during friction stir welding of nickel-based alloys

Vicharapu¹,

Lemos²,

Bergmann³

et al. 2021

Tecnol. Metal. Mater. Min.

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Friction stir welding (FSW) of nickel-based alloys can provide joints with improved corrosion resistance and mechanical properties that are deteriorated significantly during fusion welding of these alloys. However, rapid wear and poor longevity of tools are major concerns for FSW of nickel-based alloys. Polycrystalline cubic Boron Nitride (pcBN) has emerged as an alternative tool material due to its enhanced strength and stiffness but its use for FSW of nickel-based alloys is rarely explored. An investigation is therefore undertaken to examine FSW of Inconel 625, which is a commonly used nickel-based alloy, by experimental investigation and computational process modelling. The potential failure mechanisms of pcBN tools during FSW of Inconel 625 are examined. The results showed that the thermal softening of the tungstenrhenium binder phase and dissolution of tungsten into Inconel 625 are potential mechanisms to early wear and failure of the pcBN tools for FSW of Inconel 625.

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“…The peak temperature during solid state joining remains below the solidus temperature of the respective workpiece material [15][16][17][18][19][20][21][22][23][24]. Similar boundary conditions are used in numerical heat transfer modeling of FSW and stationary shoulder friction stir welding (SSFSW) processes [23,24]. The mechanical analysis was performed following the equilibrium equation 'KU = F', where K, U and F are the stiffness matrix, displacement vector and the force vector due to mechanical work, respectively.…”

Section: Theoretical Formulationmentioning

confidence: 99%

An investigation on girth friction welding of duplex stainless steel pipes

Kanan

Vicharapu

Pissanti

et al. 2020

Journal of Manufacturing Processes

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Girth friction welding is a novel technique to join co-axial linepipes with an external ring (girth) in solid state and without melting of materials. The ring or the girth is rotated between two pipes under an axial force resulting in frictional heat generation and plastic deformation along the pipe-girth interfaces. The rotation of the girth is stopped after a preset displacement of the pipes while the force is maintained to consolidate the deformed material and form the joint along the girth-pipe interfaces. Since the girth is only rotated and the pipeline sections remain stationary, the process simplifies the in situ assembly operations and enables the joining of complex configurations. As the melting of pipes and girth is avoided, the formation of harmful intermetallic compounds and deterioration of toughness in the heat affected zone are minimized. A comprehensive numerical model is reported in the present work to analyse the influence of key process variables on the rate of heat generation, resulting temperature field and thermal cycles, and the nature of material flow along the pipe-girth interfaces in girth friction welding of duplex stainless steel pipes. The computed results of thermal cycles and joint shapes are validated with the corresponding experimentally measured results. The results showed a favorable balance of the ferrite and austenite phases, and very little presence of the harmful sigma phases in the recrystallized weld-zone, which is difficult in fusion welding processes of similar materials.

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Probing residual stresses in stationary shoulder friction stir welding process

Cited by 24 publications

References 37 publications

Efficient analysis of welding thermal conduction using the Newton–Raphson method, implicit method, and their combination

Efficient analysis of welding thermal conduction using the Newton–Raphson method, implicit method, and their combination

Probing underlying mechanisms for PCBN tool decay during friction stir welding of nickel-based alloys

An investigation on girth friction welding of duplex stainless steel pipes

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