Accidental overloading effect on the S-N curve of welded joint of three steel grades

This paper focuses on the analysis of the fatigue behaviour of soldered points of tree grades of steel under loading with accidental overload. For analyzing the sensitivity of the material to accidental overloads four expressions of F-N curve are selected. Two accidental overload ratios (1.4 and 2.3) are applied. The experimental results and those of the four F-N models indicate the beneficial effect of accidental overloading for the stresses greater than the level stress of the pivot point. Below this level of stress, accidental overload is detrimental to the material. F-N curve obtained with a ratio 2.3 shows that the breaking strength Rm of the material is greater than that of the curve F-N ratio 1.4. But, the value sD of the endurance limit obtained with a ratio 2.3 is lower than that obtained with a ratio of 1.4.