Influence of Welding Parameters on Microstructure and Mechanical Performance of Resistance Spot Welded High Strength Steels

H.Ghazanfari，M.Naderi

Department of Mining and Metallurgical Engineering, Amirkabir University of Technology (Tehran Polytechnic)

摘 要：This paper presents an experimental study on physical and mechanical properties of high strength steel plates（AISI 4130）joined by resistance spot welding by means of hardness mapping technique.Welding current and electrode force were selected as experimental parameters.The welded joints were exposed to tensile-shearing tests in order to determine the strength of the welded zones.Hardness and microstructural examinations were carried out in order to examine the influence of welding parameters on the welded joints.Hardness mapping test was conducted on the large area of weld zone,including the heat afected zone and base plate.Hardness map was used to investigate the efects of current on hardness and microstructure in diferent regions of weld.Low electrode force and high welding current,used during the welding,increased the expulsion.An optimum weld quality was obtained by using 6.5 kA weld current.It was found that mechanical performance of resistance spot welded samples is controlled by nugget diameter and expulsion.Results revealed that hardness mapping technique provides one of the best methods for the physical and mechanical understanding of heterogeneous microstructures using hardness criterion.

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