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具有低屈服点、高强度、高塑性及无屈服延伸的铁素体+马氏体组织的双相铜,由于其优异的冷成型性而成为汽车减重的理想材料,被称谓“八十年代产品”。本研究以低碳 Mn-Mo 及 MnVN 铜为对象,探讨了热轧后在(α+γ)区热处理后获得80～90%铁素体+10～20%马氏体组织的工艺制度。分析了冷却速度、加热温度及保温时间对金相组织及机械性能的影响。观察了具有不同马氏体量样品的断裂特点。试验钢是在150公斤中频电炉冶炼的,试验室开坯后在现场热轧至2.5～3.0毫米,热处理是在中温盐浴炉中进行的,结果表明,冷却速度选择适当(4～8℃/秒),两相区加热温度及保温时间(5～15分)对其金相组织及机械性能无明显影响。并提供了一批样品在汽车厂进行零件的试冲,结果表明,双相钢的冷成型性远高于同等强度的低合金钢。
Biphasic copper with a ferrite + martensite structure with a low yield point, high strength, high plasticity and no yield elongation has been the ideal material for weight reduction in automobiles due to its excellent cold formability. It is called “Eighties product”. In this study, the low-carbon Mn-Mo and MnVN copper as the object, to explore the hot-rolled (α + γ) zone after the heat treatment to obtain 80-90% ferrite + 10-20% martensite microstructure. The effects of cooling rate, heating temperature and holding time on microstructure and mechanical properties were analyzed. The fracture characteristics of samples with different amounts of martensite were observed. The test steel was smelted in a 150 kilogram intermediate frequency electric furnace. The laboratory was hot-rolled to 2.5-3.0 millimeters in the field after dicing. The heat treatment was carried out in a medium-temperature salt bath furnace. The results showed that the cooling rate was properly selected (4-8 ° C / Sec), two-phase zone heating temperature and holding time (5 to 15 minutes) had no significant effect on its microstructure and mechanical properties. And provided a batch of samples for trial-punching of parts in automobile factories. The results show that the cold formability of duplex steel is much higher than that of low-alloy steel of the same strength.