以复相高强钢Trip600与深冲成形用DC04钢板材为材料,介绍了ISO 10113标准测定r值的回归方法,并探讨了与常规单一应变数据对求解r值方法的相关特性。试验表明,采用单点法测定r值时,平行试样间及不同试验机结果间的离散性较大,且r值与应变呈现显著的路径特征。屈服变形、纵向与横向引伸计在试验初始时刻的延迟效应及速度切换时的惯性效应是应变测量误差的重要来源,采用回归方法可以有效消除这些系统与或随机误差的累积。考虑引伸计系统因上述不稳定效应造成的不同步现象,当采用拟合方法时,拟合直线不应设定通过原点的边界条件。

By using high strength steel TRIP 600 with multiphase microstructures and DC04 steel sheet for deep drawing as testing materials,the determination of plastic strain ratio by regression method presented in the ISO 10113 standard (2006) was introduced,with the discussion about the relationship between the regression method and conventional method,i.e. single strain pairs method as well. It was clearly shown that the evolvement tendency of r value was significantly influenced by the strain path,leading to the scatter of r value results by conventional method. The instability of yield deformation,the initial signal delay on the threshold of testing and the inertia effect when test speed switching were the major causes of strain error,which could be removed by the regression method. Considering the unsynchronization phenomena during longitude and transverse strain measurement,the regression line fitted in the selected range should not be set with the boundary condition,i.e. not through the original of coordinate.