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在武钢CSP生产线上,通过控轧控冷工艺生产低成本低碳C-Mn钢薄板。结果表明,生产出的薄板屈服强度大于313 MPa,抗拉强度高于400 MPa,伸长率超过37%,屈强比低于0.83,冷弯性能良好,满足塑性要求,但常出现表面裂纹。从热力学角度分析出尺寸大于83 nm的硬脆粒子会引起裂纹,而钢中析出物尺寸约为30 nm,不足以引起裂纹。金相和扫描电镜观察到裂纹周围有混晶现象,计算表明混晶造成的应力集中约为120 MPa,大于F3轧制时钢带的强度,容易导致裂纹的产生。经提高开轧温度、降低终轧温度及卷取温度后,表面裂纹发生率从3.67%降低到了1.34%。
In WISCO CSP production line, through the controlled rolling and controlled cooling process to produce low-cost low-carbon C-Mn steel sheet. The results show that the yield strength of the produced sheet is more than 313 MPa, the tensile strength is higher than 400 MPa, the elongation is over 37%, the yield ratio is lower than 0.83, the cold bending performance is good and the plastic requirements are met, but surface cracks often occur. From the thermodynamic point of view, hard and brittle particles larger than 83 nm in size can cause cracks, whereas the size of precipitates in steel is about 30 nm, which is not enough to cause cracks. Metallographic and scanning electron microscopy showed the phenomenon of mixed crystals around the crack. The calculation shows that the stress concentration caused by the mixed crystal is about 120 MPa, which is greater than the strength of the strip during the rolling process of F3, which easily leads to the occurrence of cracks. By increasing the open-rolling temperature, reducing the finishing temperature and coiling temperature, the incidence of surface cracks decreased from 3.67% to 1.34%.