采用亚微米级分辨率的数字图像相关(DIC)方法, 探究了分级淬火得到的马氏体体积分数分别为33.8%和58.3%双相钢在不同拉伸变形量下的应变分配规律。结果表明: 两种双相钢在不同变形量下的微观应变分配规律相似, 应变分布都很不均匀, 且变形量较大时应变分布不均匀性更为显著; 在马氏体体积分数较小的双相钢中, 应变在铁素体和马氏体间分配的不均匀性更显著; 微区内存在应变集中的变形带, 变形带主要分布在铁素体上, 在块状马氏体间的较窄铁素体区域出现的概率比较大; 在马氏体上或相界面处也有少量应变集中的变形带, 马氏体体积分数较小时沿相界面扩展的变形带数量较多; 马氏体体积分数较大时变形带穿过马氏体的概率更大。

The strain partitioning behavior of step quenched dual phase steels with martensite volume fraction of 33.8% or 58.3% was studied in different tensile deformation degrees using digital image correlation (DIC) method of sub-micron scale. The results show that the strain partitioning behavior was similar for both dual phase steels in different deformation degrees; the strain distribution was quite inhomogeneous, especially when the deformation degree was increased; the inhomogeneity of strain partitioning behavior between ferrite and martensite was more pronounced for dual phase steel with less martensite. There were deformation bands with intense strain in the micro area, which mainly distributed in ferrite regions, especially in narrow ferrite bands between martensite. There were also few deformation bands in martensite and along the phase interfaces, and the deformation bands along the phase interfaces increased in number when the volume fraction of martensite was small. The probability of deformation bands crossing martensite was larger for dual-phase steel with large volume fraction of martensite.