Einfluss metallischer Überzüge auf flüssigmetallinduzierte Rissbildung beim Widerstandspunktschweißen höchstfester Stähle
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Beschreibung
Due to its high efficiency and robustness, resistance spot welding (RSW) is one of the most important welding processes within the sheet metal processing industry. With the increased use of hot-dipped, high strength steels, joining technology is facing new challenges. Reports show that surface and internal liquid metal embrittlement (LME)-cracking can be observed, which can potentially affect the joint strength. For this mode of cracking to occur, liquid phases, like the zinc coating for corrosion protection, need to form within the RSW-process. Under thermomechanical loads, the liquid phases may penetrate the grain boundaries of the base material. This leads to a weakening of the material and cracking may occur under comparatively lower thermomechanical loads.
The following work aims at reducing the LME-sensitivity of a sensitive steel-coatingsystem by adapting the coating system. In this context, hot tensile tests, which simulate the complex RSW-process, were used to separate the influencing factors of the RSW-process from the influencing factors of the material. The coating adaption was carried out within annealing- and coating experiments. The effectiveness of the adjustments is proven within the hot tensile tests, further analytics of the fracture surfaces of selected samples and correlating RSW-experiments. The developed approach enables the identification and reduction of potential LME-risks on laboratory quantities within the early stages of the product development process.
Autor*in
Daniel Schwanke
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Beschichten Beschichtung Flachstahl Flüssigmetallinduzierte Rissbildung Flüssigmetallversprödung Höchstfester Stahl LME Liquid Metal Embrittlement Stahl Werkstoffkunde Werkstofftechnik Widerstandspunktschweißen