Review of resistance spot welding of steel sheets Part 1 Modelling and control of weld nugget formation

Resistance spot welding (RSW) is a very complicated process involving electromagnetic, thermal, fluid flow, mechanical, and metallurgical variables. Since weld nugget area is closed and unobservable using experimental means, numerical methods are generally used to reveal the nugget formation mechanism. Traditional RSW models focus on the electrothermal behaviors in the nugget and do not have the ability to model mass transport caused by induced magnetic forces in the molten nugget. In this paper, a multiphysics model, which comprehensively considers the coupling of electric, magnetic, thermal, and flow fields during RSW, temperature-dependent physical properties, and phase transformation, is used to investigate the heat and mass transport laws in the weld nugget and to reveal the interaction of the heat and mass transports and their evolutions. Results showed that strong and complicated mass transport appears in the weld nugget and substantially changed the heat transport laws and, therefore, would be able to substantially affect the hardening, segregation, and residual stress of the weld. Compared with the traditional models which could not consider the mass transport, the multiphysics model proposed in this paper could simulate the RSW process with higher accuracy and more realities.

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Numerical Analysis of Transport Phenomena in Resistance Spot Welding Process

Volume 1: Symposia, Parts A, B and C ◽

10.1115/fedsm2009-78210 ◽

2009 ◽

Author(s):

Yong Bing Li ◽

Zhong Qin Lin ◽

Li Li ◽

Guan Long Chen

Keyword(s):

Mass Transport ◽

Resistance Spot Welding ◽

Spot Welding ◽

Welding Process ◽

Weld Nugget ◽

Resistance Spot ◽

Nugget Formation ◽

Electro Magnetic ◽

Physics Model ◽

Thermal Fluid Flow

Resistance Spot Welding (RSW) is a very complicated process involving electro-magnetic, thermal, fluid flow, mechanical and metallurgical variables. Since weld nugget area is close and unobservable with experimental means, numerical methods are mainly used to reveal the nugget formation mechanism. Traditional RSW models focus on the electro-thermal behaviors in the nugget, and do not have the ability to model mass transport caused by induced magnetic forces in the molten nugget. In this paper, a multi-physics model, which comprehensively considers the coupling of electric, magnetic, thermal and flow fields during RSW, temperature-dependent physical properties and phase transformation, is used to investigate the heat and mass transport laws in the weld nugget and to reveal the interaction of the heat and mass transports. Results show that the heat transport behaviors in the weld nugget, the profile of the nugget, and the thermal field evolution are significantly changed when the mass transport is considered. At the same time, a good agreement is also found between experimental and numerically calculated nugget sizes. As a result, when predicting crystal growth process, the effects of the mass transport should be considered in order to obtain a more accurate prediction results.

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