基于应变设计的X70直缝埋弧焊管应变硬化能力研究

从A、B两种轧制状态的X70抗大变形钢板制成的钢管中取样，用板状试样测定了拉伸应力-应变曲线，计算了该钢的应变硬化指数n值，研究了时效及两种轧制状态的n值分布规律。结果表明，工艺B状态的钢管时效前n统计均值为0.116 0，时效后n统计均值为0.112 0，下降约3.4%；工艺A状态的钢管时效前n统计均值为0.115 0，时效后n统计均值为0.105 4，下降约8.3%。X70工艺B状态钢管的n值、屈强比及屈服强度呈明显线性关系。0.8%和1.4%扩径率对应钢管的应变硬化指数n值差别不大，但1.4%扩径率对应钢管的均匀延伸率均值下降明显，比0.8%扩径率对应钢管均匀延伸率均值低约2%。

Study on the Strain Hardening Ability of X70 SAWL Pipe Based on Strain Design

Plate samples were sampled from A,B two kinds of rolling state of the X70 SAWL pipe with large deformation resistance.The stress-strain curve of tensile performance was inspected by using plate sample,the strain hardening exponent(n value) were calculated,the strain aging and the distribution rule of rolling state on n value were studied.The results showed that the statistical average n value of the B state samples is 0.116 0 before aging,and the value is 0.112 0 after aging,the value reduced by 3.4%;the statistical average n value of the A state samples is 0.115 0 before aging,and the value is 0.105 4 after aging,the value reduced by 8.3%.The n value is linearly proportional to yield ratio and yield strength.The 0.8% and 1.4% expanding rate have little difference on strain hardening exponent(n value),but the 1.4% expanding rate corresponding to uniform elongation decreased significantly,the uniform elongation value of 1.4% expanding rate is lower about 2% than that of 0.8% expanding rate.