Low Cycle Fatigue Behavior of DP980 Steel Gas Metal ARC Welding Joints

Keywords

DP980 steel sheet; low cycle fatigue; gas metal arc welding; heat affected zone; tempered martensite

Abstract

Dual phase (DP) steels, which are widely used in automotive industry, have a good balance between high strength and ductility. These capacities are reached due to a perfect phase combination in the DP microstructures. However, automotive parts manufactured with DP steel are often joined by arc welding processes, which generates a heat affected zone. In addition, during service, the components are subjected to cyclic loadings that can exceed the yield strength locally (besides the geometry of the component). In this work, 1.6 mm-thick DP980 steel sheets were welded by gas metal arc welding process to analyze the low cycle fatigue behavior. The tests were conducted under a constant amplitude strain control mode. The welded joints experienced a fatigue life reduction with respect to the DP980 steel of ~16% at strain amplitudes of 0.2, 0.3, and 0.4%. For strain amplitudes larger than 0.6%. The fatigue life of the welded joint was reduced by 39%.

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