卷取温度对薄板坯连铸连轧含硼低碳钢板性能的影响

Effect of coiling temperature on the properties of low carbon steel with boron produced by TSCR

本文以包钢TSCR生产线生产的5mm厚加硼低碳冷轧基板为研究对象,利用光学显微镜、扫描电镜观察了含硼热轧、退火板的金相组织,并通过拉伸试验以及电解化学相分析实验研究了卷取温度对钢板深冲性能的影响,对冷轧基板中第二相粒子强化作用的影响做了深入探讨。研究表明,卷取温度影响热轧后铁素体晶粒的大小,卷取温度越高,晶粒平均尺寸越大。钢板的伸长率和n值分别在50%和0.23左右。四个卷取温度相比较,深冲钢屈服强度和抗拉强度差异不大,r值达到最大值1.466,获得良好的深冲性能。粒度分析表明,570℃卷取冷轧钢板中析出M3C粒子在1～10nm的占钢的质量分数为0.0445%,比600℃卷取冷轧钢板中析出的M3C粒子高0.0028%,对强度贡献大。

In this study a 5 mm thickness low carbon B-steel hot band from BaoGang Group Co., LTD was tested as a sample. The microstructures of hot band and annealing sheet were observed by optical microscopy and scanning electronic microscopy, while the influence on deep drawability of the steel sheet at different coiling temperatures was studied by tensile test and electrolytic chemical phase analysis, and the strengthening effect of second-phase particle was also studied in details. The results demonstrated that the ferrite grain size is affected by coiling temperature, the higher the coiling temperature, the larger the mean size of the grain is. The elongation rate and the n value are about 50% and 0.23, respectively. At the four coiling temperatures, the yield strength and tensile strength of deep drawing sheet are similar, while r value reaches the peak value 1.466, thus, the deep drawability is good. By the analysis, the mass percentage of M3C precipitates with the size range of 1~10 nm in hot band coiled at 570℃ is 0.044 5%, which is by 0.002 8% higher than 0.041 7% in hot band coiled at 600℃. Therefore, 570℃ has more contribution to the strength.