【摘要】 试制了C-Si-Mn冷轧双相钢。采用力学测试、显微组织观察与修正的C-J分析方法研究了双相钢的应变硬化特性。研究结果表明,双相钢的应变硬化具有两阶段。第一阶段应变硬化能力较强,第二阶段硬化能力减弱。两阶段硬化之间存在一个转折应变。当马氏体体积分数小于16%,随马氏体体积分数的增加,两阶段硬化能力均增强。当马氏体体积分数大于16%,随马氏体体积分数的增加,两阶段硬化能力均减弱。硬化转折应变则随马氏体体积分数增加单调递减。铁素体与马氏体的弹塑性行为差异是导致双相钢两阶段硬化的主要原因。马氏体体积分数增加,其强化效果增加,但是由于马氏体中的碳含量降低,其塑性抗力降低。只有当马氏体量增加带来的强化效应大于碳含量减少的弱化效应时,双相钢的应变硬化能力才随之增加。更多还原

【Abstract】 A cold rolled dual phase steel with C-Si-Mn alloy system was piloted.Strain-hardening characteristics of the trial steel were investigated by using mechanical test,microstructure observation and modified C-J analytical method.The results show that there exist two stages in the strain-hardening process of dual phase steel.The strain-hardening ability is strong in the first stage while weak in the second stage.There is a transition strain existing between the two stages.Strain-hardening abilities of both stages strengthen with the increase of martensite volume fraction(Vm) when Vm is less than 16%,but weaken with the increase of Vm when Vm exceeds 16%.The transition strain monotonically decreases with the increase of Vm.The difference of elastic-plastic behaviors between ferrite and martensite in dual phase steel is the main reason to induce two stage hardening characteristics.The increase of Vm could improve strengthening effects,but the plastic resistance of martensite decreases due to the dilution of carbon content in martensite.Only when the strengthening effect caused by the increase of Vm is more than the weakening effect caused by the decrease of carbon content in martensite,strain-hardening ability of dual phase steel could increase.更多还原