基于X70管线钢n值计算方法的优化

Optimization of n value calculation method based on X70 pipeline steel

鉴于中厚板应变硬化指数(n值)暂无规范的计算标准,本文利用代表体积单元(RVE)有限元模拟的方法,结合实验探究了X70管线钢宏观应变硬化指数(n值)与微观组织之间的关系,并结合薄板n值计算方法对X70管线钢中厚板n值计算方法进行优化。结果表明:RVE模型可以准确描述X70管线钢中厚板宏观力学性能与微观组织之间的关系。计算X70管线钢n值时,选择发生位错机制的塑性阶段最合理。其中P_(17.5)/P_(7.5)两点法较四点法、七点法计算更方便且准确,结果误差≤1%。

In view of the fact that there is no normative calculation standard for the strain hardening index(n value)of medium and thick plates,this paper uses the representative volume element(RVE)finite element simulation method,combined with experiments to explore the relationship between the macroscopic strain hardening index(n value)and the microstructure of X70 pipeline steel,and combines the thin plate n value calculation method to optimize the n value calculation method of medium and thick plates for X70 pipeline steel.The results show that RVE model can accurately describe the relationship between macro mechanical properties and microstructure of the X70 pipeline steel plate.When calculating the n value of the X70 pipeline steel,it is the most reasonable to select the plastic stage where dislocation mechanism occurs.The P_(17.5)/P_(7.5) two-point method is more convenient and accurate than four point method and seven point method,and the error is less than 1%.