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Joining Mechanism and Strength Evaluation on Spot Welding of IF Steel Sheets
Published May 19, 2010 by Society of Automotive Engineers of Japan in Japan
Event: JSAE Spring Conference
In this study, we had much attention to the spot-welding of two IF steel sheets that have lower electrical resistance in all of the automobile steel sheets. The effects of welding time on the tensile strength were investigated on various conditions, which were the pressing force and the welding current. The tensile strength of welding joints was saturated with the increase of welding time irrespective of the welding condition (current value and pressing force). Two fractured types (plug and shear types) were found in the specimens after tensile tests. Meanwhile, there is no difference of fracture mechanism between plug and shear type. The crack propagated going around the hardening nugget on both types of fracture. The excessive welding energy off the optimal condition might induce the decrease of tensile shear strength due to the welding defects, which are the dent of nuggets area on the higher current value, and non-growing of nugget on the higher pressing force.