An Assessment of the Fatigue Performance of Automotive Sheet Steels

This paper presents an overview of strain-controlled and spot-welded fatigue data for a variety of automotive sheet steels, including materials ranging from mild steel to advanced high strength dual phase and TRIP steels. Using both ISG fatigue results and those made available in the recent literature, general trends in fatigue resistance as a function of base metal mechanical properties are identified. Although fatigue resistance is shown to increase with increased strength in the base condition, the fatigue performance of spot-welded joints made from these same steels appears to be insensitive to the material properties and is essentially a function of joint geometry. Implications for vehicle design are discussed.