DEFORMATION AND FATIGUE BEHAVIOR OF A COLD-ROLLED SAE 1010 STEEL

An SAE 1010 low-carbon steel was cold rolled to 22, 56 and 76% thickness reductions. Monotonic tensile tests, smooth and notched specimen fatigue tests and crack propagation tests were performed. The effect of loading direction on fatigue behaviour was examined. The monotonic and cyclic yield strengths increased and the ductility decreased as the degree of cold rolling increased. The increase in yield strength and the decrease in ductility were more pronounced in the transverse direction than in the longitudinal direction. Under strain control, the fatigue life at high strain amplitudes was lower for loading in the transverse direction than for loading in the longitudinal direction. At low strain amplitudes the fatigue lives in both directions were approximately equal. The notched specimen fatigue strength was only slightly increased by cold rolling since two opposing factors, the smooth specimen fatigue strength and the notch sensitivity, were both increased by cold rolling. The threshold stress intensity decreased and the crack propagation rate, at a given stress intensity, increased as the degree of cold rolling increased.