Push-Pull Low Endurance Fatigue of En 25 and En 32B Steels at 20°C and 450°C

Abstract

Mild steel (En 32B) and a 2 1/2 Ni-Cr-Mo steel in soft and heat treated conditions were subjected to reversed uniaxial strain cycling at 20°C and 450°C with continuous cycling at 2–10 c/min and also 10 min hold-times. The results are plotted in graphical form from which a number of empirical relationships are derived between plastic strain range, stable stress range, cycles to failure, strain energy, and true fracture ductility and strength. High temperature causes a marked reduction in strength for both materials, which is greater at the lower strain ranges, compared with room temperature cycling. There is little or no effect due to hold-time compared with continuous cycling at room temperature for En 25 (heat treated). There is only a slight reduction in strength at 450°C, but the situation is likely to be worse for longer hold-times.