基于修正C-J法和RVE模型的780MPa级冷轧双相钢的应变硬化行为

Characterization and Simulation of Strain-hardening Behavior of a Cold-rolled Dual Phase Steel of 780 MPa Grade by Means of Modified C-J Method and RVE Model

针对经不同工艺热处理的780 MPa级冷轧双相钢板,采用修正的C-J(Crussard-Jaoul)法分析了应变硬化行为,并基于真实组织形貌的代表性体积单元(Representative volume element,RVE)模型模拟其形变行为。结果表明:不同状态的实验钢均表现出较高的初始应变硬化率。岛状和针状马氏体表现出两阶段应变硬化特征,依次对应铁素体塑性变形和铁素体/马氏体协同塑性变形;当马氏体为粗大块状呈现三阶段应变硬化特征,其中第三阶段主要发生马氏体塑性变形时应变硬化能力下降明显。模拟结果表明:当块状和针状马氏体的应变集中分布在铁素体和马氏体界面,岛状马氏体的应变集中分布在马氏体块的连接部位。

The strain-hardening behavior of a cold-rolled dual phase steel of 780 MPa grade after different heat treatments was analyzed by a modified Crussard-Jaoul（ C-J） method, and the deformation behavior of which was simulated with representative volume element（RVE） model. The results show that dual phase steels of different states all exhibit higher initial strain-hardening rate. The steel containing island-and needle-like martensite showed two-stage strain-hardening characteristics which related to the plastic deformation of ferrite and coordination plastic deformation of ferrite and martensite respectively,while the steel containing coarse block-like martensite exhibited three-stage strain-hardening characteristics and of which, the strain hardening capacity of the third stage decreases significantly due to the plastic deformation. The finite element method（FEM） simulation result showed that the strain concentration of the dual phase steel containing coarse block-and needle-like martensite mainly distributed in the interface of ferrite and martensite, while that containing island-like martensite distributed in junctions of martensite grains.