An Analysis of the Transient Nugget Formation in Resistance Spot Welds

An analytical model is presented to describe the transient nugget growth in resistance spot welds. Since an exact analysis of this model is difficult, due to complexities arising from the interaction of heat and electric current flow, and from the melting of the weldment, an approximate solution is proposed by employing the integral method and some previous results obtained by the authors (13). With the aid of this analysis a simplified nugget growth equation is derived, which can be effectively used for the design of an adequate on-line feedback control algorithm. To verify the validity of this model equation, the computed results are compared with those experimentally obtained for the case of welding of mild steels. The comparison shows that the transient nugget behaviour is well predictable by the proposed model for the welding conditions in this simulation study.

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Machine Learning Modeling and Hyper-Parameter Optimization for Weld Nugget Formation and Failure Behavior of Resistance Spot Welds

Journal of Welding and Joining ◽

10.5781/jwj.2021.39.6.11 ◽

2021 ◽

Author(s):

Hyeonjeong You ◽

Cheolhee Kim

Keyword(s):

Machine Learning ◽

Parameter Optimization ◽

Weld Nugget ◽

Failure Behavior ◽

Spot Welds ◽

Resistance Spot ◽

Resistance Spot Welds ◽

Nugget Formation

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Transient Softening at the Fusion Boundary of Resistance Spot Welds: A Phase Field Simulation and Experimental Investigations for Al–Si-coated 22MnB5

Metals ◽

10.3390/met10010010 ◽

2019 ◽

Vol 10 (1) ◽

pp. 10 ◽

Cited By ~ 1

Author(s):

Oleksii Sherepenko ◽

Omid Kazemi ◽

Paul Rosemann ◽

Markus Wilke ◽

Thorsten Halle ◽

...

Keyword(s):

Phase Field ◽

Welding Process ◽

Phase Evolution ◽

Experimental Investigations ◽

Spot Welds ◽

Fusion Boundary ◽

Carbon Solubility ◽

Resistance Spot ◽

Resistance Spot Welds ◽

Nugget Growth

This work gives an insight into the transient softening at the fusion boundary of resistance spot welds on hot stamped steel. Metallographic investigations and hardness mapping were combined with finite phase–field modeling of phase evolution at the fusion boundary. Saturation of weld nugget growth in the welding process was observed. For industrially relevant, long welding times, the fusion boundary of a spot weld is therefore isothermally soaked between the peritectic and solidus temperatures. This leads to a carbon segregation to the liquid phase due to higher carbon solubility and possibly to δ-Fe formation at the fusion boundary. Both results in a local carbon depletion at the fusion boundary. This finding is in good agreement with carbon content measurements at the fusion boundary and the results of hardness measurements.

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Three-Sheet Spot Welds of 5052 Aluminum Alloy: Weld Growth and Failure Behavior

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.782.158 ◽

2015 ◽

Vol 782 ◽

pp. 158-163 ◽

Cited By ~ 1

Author(s):

Fu Yu Yan ◽

Zhen Luo ◽

Yuh J. Chao ◽

San San Ao ◽

Yang Li ◽

...

Keyword(s):

Aluminum Alloy ◽

Failure Modes ◽

Peltier Effect ◽

Failure Behavior ◽

Spot Welds ◽

Resistance Spot ◽

Pull Out ◽

Resistance Spot Welds ◽

Nugget Formation ◽

Alloy Weld

Resistance spot welding is used extensively in auto industry. Every commercial vehicle has 4000-5000 spot welds. The weld ability, performance, and reliability are therefore important issues in design. In this paper, we studied weld nugget formation and failure behavior of three-sheet 5052 aluminum alloy resistance spot welds. The Peltier effect between the Cu-Al (the electrode and the Al worksheet) to the nugget formation was noticed. The mechanical strength and fracture mode of the weld nuggets at the upper and lower interfaces were studied using tensile shear specimen configuration. Three failure modes were identified, namely, interfacial, mixed, and pull-out. The critical welding time and critical nugget diameter corresponding to the transitions of these modes were investigated. Finally, an empirical failure load formula for three-sheet weld similar to two-sheet spot weld was developed.

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