The mechanical properties in tailor rolled blank of dual phase steel (DP-TRB) at different thickness zones present significant differences after annealing. In this paper, the differences in mechanical property of the tailor rolled blank were investigated. The work hardening behavior is analyzed by C-J analysis method. The results indicate that the microstructure of DP-TRB is composed of ferrite and martensite at 800–820 °C. It is interesting that the martensite islands gradually chang to equiaxed morphology from rod-like shape at annealing temperature of 800 °C. In addition, the differences in mechanical properties between different thicknesses zones become less with the increased intercritical temperature from 760 °C to 820 °C. It indicates that the difference in yield strength decreases from 230 MPa to 60 MPa with the intercritical temperature changing from 760 °C to 820 °C. Ferrite recrystallization or not is the main reason for the differential properties. The critical thickness for recrystallization is same ~ 1.6 mm, and the 1.6 mm zones is experimentally proved to possess the largest strength at 760 °C, 800 °C, and 820 °C. The samples in thinner zones are softened because of the recrystallization, while the samples in the larger thickness zone are not strong enough as 1.6 mm with less work-hardening. After the yield point, there is an extra work hardening stage in 1.6 mm and 1.8 mm samples relative to 1.0–1.4 mm samples, which can eliminate nonuniform deformation and prepare for the followed uniform deformation. Consequently, turning of this feature of properties differentiation rationally would play an important role in application of DP-TRB.

退火后，双相钢（DP-TRB）的定制轧制坯料在不同厚度区域的力学性能存在显着差异。在本文中，研究了定制轧制毛坯的机械性能差异。用CJ分析法分析加工硬化行为。结果表明，DP-TRB的显微组织在800–820°C时由铁素体和马氏体组成。有趣的是，在800°C的退火温度下，马氏体岛逐渐从棒状转变为等轴形态。此外，随着临界温度从760°C升高到820°C，不同厚度区域之间的机械性能差异变得越来越小。结果表明，随着临界温度从760°C变为820°C，屈服强度差从230 MPa减小到60 MPa。是否有铁素体再结晶是产生差异特性的主要原因。重结晶的临界厚度相同，约为1.6 mm，实验证明1.6 mm的区域在760°C，800°C和820°C时具有最大强度。较薄区域中的样品由于重结晶而软化，而较厚区域中的样品强度不足至1.6 mm，而加工硬化较少。在屈服点之后，相对于1.0-1.4 mm的样品，在1.6 mm和1.8 mm的样品中还有一个额外的加工硬化阶段，这可以消除不均匀的变形并为随后的均匀变形做准备。所以，