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本文研究了热轧态铁素体+马氏体型双相钢线材冷拔—回复—冷拔过程(简称LHL工艺)的力学性能及显微组织的变化。试验结果表明:(1)双相钢线材的冷拔形变强化可分两个阶段,第一阶段为减速强化阶段,在σ—ε曲线上的斜率(dσ/dε)随ε的增加而减小。第二阶段为恒速强化阶段,σ—ε关系符合珠光体型冷拔强化的Embury-Fisher关系。第一阶段与第二阶段分界的ε值约为1.20—1.50;(2)双相钢的冷拔强化虽然可以获得2300MPa以上的强度水平,但塑性、韧性严重恶化,难以实际应用。冷拔钢丝的回复及回复后的冷拔,是双相钢冷拔形变强化及韧化的有效途径。本文用SEM、TEM电镜观察了显微组织,对LHL工艺的强化与韧化机理进行了分析。
In this paper, the mechanical properties and microstructure changes of hot-rolled ferritic + martensitic dual-phase steel during cold drawing-reclaiming-cold drawing process (LHL) were studied. The results show that: (1) Cold drawing deformation of dual-phase steel wire can be divided into two stages. The first stage is the stage of decelerating and strengthening. The slope (σσ / dε) on σ-ε curve decreases with the increase of ε . The second stage is the constant-speed strengthening stage, and the σ-ε relationship is consistent with the Embury-Fisher relationship of pearlite cold drawing. The ε value of the boundary between the first stage and the second stage is about 1.20-1.50. (2) Although the strength of duplex steel can be obtained above 2300MPa, the ductility and toughness of the duplex steel deteriorate severely and are hard to be practically used. The recovery of cold-drawn steel and cold-drawn after the recovery, is an effective way of dual-phase steel cold drawn deformation and toughening. In this paper, the microstructure was observed by SEM and TEM, and the strengthening and toughening mechanism of LHL process was analyzed.