高强度冷轧双相钢应变硬化行为

Strain-hardening behavior of cold rolled dual phase steel with high strength

为了研究双相钢在变形过程中的应变硬化特性,采用Hollomon法与修正的Crussard-Jaoul法分析了试验钢的应变硬化曲线,并利用力学测试与显微组织观察等手段研究了组织结构对应变硬化行为的影响机制.结果表明:三种试验钢,均表现出较高的初始加工硬化能力.具有岛状马氏体与类针状马氏体的双相钢表现出两个阶段的应变硬化特征,具有粗大块状马氏体的双相钢则表现出三个阶段的硬化特征.与类针状和粗大块状马氏体相比,含有岛状马氏体的双相钢表现出较强的加工硬化能力和强度与塑性的良好配合.块状马氏体较早的进入塑性变形,导致双相钢变形协调难度加大并在晶界周围产生孔洞而使塑性恶化.

In order to research the strain-hardening characteristics of dual phase （DP） steels during deformation, the strain-hardening curves of experimental steels were analyzed with Hollomon and modified Crussard-Jaoul （C-J） methods. And the influencing mechanism of microstructure on the strain-hardening behavior was investigated with mechanical property tests and microstructural observation. The results show that three kinds of experimental steels all exhibit higher initial work-hardening capability. The DP steels containing island-shaped and needle-like martensite show two-stage strain-hardening characteristics, while the DP steel containing coarse massive martensite exhibits three-stage strain-hardening characteristics. Compared with the DP steels containing needle-like and coarse massive martensite, the DP steel with island-like martensite possesses stronger working-hardening capability and better match in both strength and plasticity. The massive martensite participates in plastic deformation at earlier stage, which increases the difficulty in the deformation compatibility of DP steel and causes the deterioration in the plasticity due to the appearance of voids around grain boundaries.