为了研究屈强比升高对管线钢使用安全性的影响, 测试了5种常用钢材的工程应力及真应力-真应变曲线, 计算了名义屈强比、真实屈强比和静力韧度。结果表明: 随着钢强度级别的升高, 名义屈强比会不断升高, 材料的塑性指标有下降的趋势; 真实屈强比在表征材料塑性变形余量方面比名义屈强比更客观, 名义屈强比放大了屈强比升高的安全隐患; X80管线钢的屈强比虽然较高, 但其抵抗变形的能力并未降低; 对高强度管线钢规定过低的屈强比, 会造成不必要的浪费。

The nominal yield ratio, true yield ratio and static toughness of five normal steels were calculated and the engineering stress, true stress and true strain curves were tested to analyze the effects of yield ratio rising on the use security of pipeline steels. The results show that the nominal yield ratio increased gradually and the plasticity index decreased with the increase of the strength level. Comparing with the nominal yield ratio, it was more objective to use the true yield ratio to characterize plastic deformation, and the nominal yield ratio magnified the potential safety hazard caused by raising yield ratio. The yield ratio of X80 pipeline steel was high, but its capability of resisting deformation did not decrease. It would cause unnecessary waste to require fairly low yield ratio for high strength pipeline steels.