Abstract
The requirement of the high processing high strength light steel sheet recently rises in the car from the global environmental problems and so on from the body lightening because of fuel expenses and the view point of the safety improvement at the time of the collision. In the present paper, fatigue properties of extra-low carbon steels with different tin contents, varied from 0.002 to 0.22% mass, are investigated. The results show that the fatigue strength by (10)^7 cycles increases with increasing Sn content.The fatigue strength of annealing specimens at 750℃ is higher than that at 650℃. The cracks initiated from the surface of specimen and propagated mainly in intergranular modes for all materials.
