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针对硬线钢盘条拉拔断裂问题,分别对拉拔性能较差批次的盘条和在拉拔过程中断裂的产品取样,采用光学金相显微镜、拉伸试验机、扫描电镜和能谱仪对其表面质量、化学成分、力学性能、夹杂物、显微组织和中心偏析等分析。结果表明:盘条拉拔断裂的主要原因是盘条中存在中心孔洞及中心碳偏析,其次是在断口存在的Al_2O_3夹杂物和大颗粒球状夹杂物,在拉拔过程中形成微裂纹并逐步扩展导致断裂。通过确保精炼钢包底吹效果,控制中包过热度及温度波动分别在20~35℃和±5℃,稳定连铸拉速和波动分别在2 m/min和±0.2 m/min后,铸坯内部缺陷明显减轻,盘条拉拔断裂现象减少。
In order to solve the drawing and breaking problem of hard wire rod, samples of wire rod with poor drawing performance and products broken during drawing were respectively sampled. Optical microscope, tensile testing machine, scanning electron microscope and energy spectrum Instrument on its surface quality, chemical composition, mechanical properties, inclusions, microstructure and center segregation analysis. The results show that the main reason of wire rod fracture and fracture is the presence of central hole and center carbon segregation in the wire rod, followed by the presence of Al 2 O 3 inclusions and large spherical inclusions in the fracture. Microcracks are formed during the drawing and are gradually extended Lead to fracture. By ensuring that the ladle bottom blowing effect of the ladle is controlled, the degree of superheat and the temperature fluctuation in the control package are controlled at 20 to 35 ° C and ± 5 ° C, respectively, and after stable casting speed and fluctuation are respectively 2 m / min and ± 0.2 m / min, Significantly reduce the internal defects, wire rod fracture phenomenon reduced.