What is it about?

Spot welding technology of sheets made of Dual-Phase (DP) steel, which is one of the most important materials in the automotive industry. Besides conventional mild steels that have been dominant for decades in automobile production, the application of advanced high-strength steels (AHSS) comes into focus. Among the first generation AHSS, DP steels are of the utmost importance concerning their automotive use. During the spot welding of DP steels, when using the technology familiar with mild steels, the risk of hardening, the unfavourable failure of the joint or even cracking during operation must be taken into account, therefore welding technology must be planned on different theoretical bases.

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Why is it important?

For numerical analysis an axisymmetric coupled finite element model was developed to study the effect of welding time and current intensity on nugget size and thermal history in resistance spot welding process. The cross-section macrostructures of the welded specimens were examined and compared to the predicted size of the weld nugget and heat affected zone. Shear testing, cross tension testing, peel testing and hardness measurements were also performed on specimens for each welding process to examine the effect of the changes in different welding parameters on the load bearing capacity of the joint. Using an appropriately increased intermediate time between pulses a part of or the entire weld nugget could be recrystallized and tempered with the second current pulse, the microstructure of spot welds in DP steels could be fined, their hardness distribution and the conventional static mechanical properties and dynamic load capacity could be significantly improved.

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This page is a summary of: Development of Resistant Spot Welding Technology for Automotive Ferrite-Martensitic Dual-Phase Steels with Joint Application of Finite Element Modelling and Experimental Research, Advanced Materials Research, July 2016, Trans Tech Publications,
DOI: 10.4028/www.scientific.net/amr.1138.43.
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