研究了缓慢冷却速度和缓慢冷却终止温度对C—MnCr系冷轧双相钢的显微组织和力学性能的影响。结果表明，随缓慢冷却速度的增加，试验钢的强度增加，伸长率则减小，屈强比变化不大，均在0．46左右。在不同缓慢冷却速度下，试验钢的显微组织均由铁索体和马氏体组成，随着缓慢冷却速度的增加，晶粒尺寸逐渐减小，马氏体体积分数明显增多。铁素体中存在非连续的碳化物沉淀相，能谱分析表明，该沉淀相为（Fe，Cr，Mn）3C，并且在较慢的缓慢冷却速度下，这种非连续的碳化物沉淀相数量少、尺寸大。缓慢冷却终止温度从590℃增加到680℃，试验钢的强度略有降低，而缓慢冷却终止温度超过700℃后，强度迅速降低，伸长率呈上升趋势，屈强比基本不变。在低缓慢冷却终止温度下，试验钢的显微组织由铁素体和马氏体组成，并且马氏体中存在微细孪晶，而在高缓慢冷却终止温度下的马氏体则为板条状。
The effect of slow cooling rate and slow cooling end temperature on microstructures and properties of C- Mn Cr cold rolled dual phase steel was investigated. The results show that with increase of the slow cooling rate, the strength of the trial steel is increased, the elongation is decreased, and the yield ratio is about 0.46 constant. Under different slow cooling rate, the microstructure of trial steel is composed of ferrite and martensite. Grain sizes gradual reduce and martensite volume fraction increase markedly with increasing of slow cooling rate. It is （Fe, Cr, Mn）xCy analyzed by energy spectrum that discontinuous precipitated phase exist in ferrite. When the slow cooling rate is lower, its quantity is fewer and its size is bigger. The strength of trial steel reduces slightly while slow cooling end temperature raise from 590 to 680℃. But when the temperature exceed 700℃, the strength decrease rapidly, the elongation rise, yield ratio change a little. At low slow cooling end temperature, the microstructure of trial steel is composed of ferrite and martensite and micro-twins exist in martensite. While the martensite is lath-shaped at high slow cooling end temperature.
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