The Effect of Rotatory Bending Stress on the Hardness of Low Carbon Steel

Abstract

We measured the micro-Vickers hardness of 0.13%-carbon steel, which had been subjected to a rotatory bending stress. The hardness testing was held under 50 gram and l000 gram loads. Summary of the results is as follows : (1) The increase of the hardness number of ferrite is not always dependent on the magnitude of the repeated stress at the measuring point and the number of stress cycles. (2) The hardness number of the ferrite, which has been increased by the repeated stress lower than the yielding point, is reduced to the hardness of the centre of the cross section by annealing at 600°C for three hours. (3) But the same heat-treatment cannot recover the hardness of the pearlite at the same condition to the previous state.