Influence of the Welding Process on Changes in the S460MC Fine-grained Steel Joints Fatigue life

Structural designs of the dynamically loaded welded structures are currently based primarily on the values of the parent base material fatigue life. Although it tries to capture the influence of the given process by using the safety constants of the notch effect both of the weld and the thermal influence, it is only a theoretical estimation. Due to that, it very often results in large oversizing and, in worse cases, in under-sizing of the engineering design. As a result, there is either an overly robust and heavy construction, which is unacceptable (especially when applied in the automotive industry) or on the contrary, there is failure of parts due to cracks earlier than their planned service life is reached. The paper shows the effect of MAG welding method on the fatigue life of fillet and butt welds made of the fine-grained structural steel S460MC. The comparison of such influence is performed via using experimentally determined Wöhler curves of the parent material and both types of welded joints.