EFFECT OF PRE-STRAIN ON TORSIONAL FATIGUE PROPERTIES OF MIDDLE CARBON STEEL
预应变对中碳钢扭转疲劳特性的影响

Fatigue test was performed to investigate the reversed torsional fatigue properties of non-pre-strained carbon steel and three kinds of pre-strained carbon steel. Main results summarized in this study are as follows: In the case of pre-strain rate lower than 5{\%}, the fatigue limit is 10{\%} lower than the non-pre-strained specimen. In the case of pre-strain rate higher than 5{\%}, the fatigue limit increases with increasing pre-strain rate. For the pre-strain rate of 8{\%}, the fatigue limit is equal to the fatigue limit of non-pre-strained specimen. The non-propagatinig cracks are observed in all specimens' surfaces after 1$\times $10$^{7}$ cycles under the stress amplitude of fatigue limit.