Fatigue strength of sheet steel

This report summarizes recent studies on fatigue strength in sheet steel, with special regards to high tensile strength steel (HTSS) 1) Fatigue strength in a smooth specimen increase with tensile strength below 700 MPa. 2) Pre-straining improves fatigue strength, however this effect on HTSS above 600 MPa is limited. Thermal aging such as paint baking after prestraining, is effective in improving fatigue strength in HTSS. 3) Fatigue strength of a notched specimen with a shearing edge or punched hole, does not increase with tensile strength. 4) Fatigue strength of spot and arc welded joints does not depend on tensile strength but microstructure and welding procedure. Therefore, fatigue strength can be increased using joints whose tensile residual stress and stress concentration are relatively small.