X80钢弯曲的力学性能测试

针对钢管制管过程中钢材板卷反复弯曲展平对钢材强度的影响，对X80钢制成的试样进行了4点弯曲实验．在各弯曲试样得到不同的预应变后，又对其进行反向加载，记录不同预应变下各试样反向加载的弯矩随表面应变的变化曲线．实验结果表明，存在预应变后，试样的弯矩-应变曲线低于初次加载的弯矩-应变曲线，且试样的预应变越大，弯矩-应变曲线越低，即随预应变的增加，材料的屈服强度降低，且出现了包申格效应．通过进一步理论计算，得出了材料预弯到屈服后再反向加载时，不同预应变下的屈服弯矩值，且实验测试和理论计算的屈服弯矩值能较好地吻合．

Mechanical property test of X80 steel

In order to study the steel pipe strength change occurred during the manufacturing process, schemes of four bending experiments of X80 Steel were made in this paper. In these experiments, speci- mens were bending to produce different pre-strain respectively, and then reverse bending were taken one by one. The Monmet-strain curves were recorded. The results show that the specimens is work-hardening under the reverse loading and the yield strength is lower than that of the first forward loading test, and the yield strength difference increased as the pre-stain grew. In this paper the yield moment were also calculated according to elastic-plastic mechanics, the agreement between measurements and calculations is very good.