连铸板坯凝固末端大压下改善铸坯内部质量

探讨了单对辊凝固末端大压下对连铸板坯内部质量的影响。研究中,分析检测了不同拉速条件下Q345D连铸坯低倍组织特征,并对铸坯中心疏松进行了定量测量。结果表明,采用大压下能够有效改善连铸坯的内部质量。拉速为0.70 m/min时,大压下15 mm相比轻压下时铸坯在宽度1/2位置、1/4位置处的中心疏松体积均明显降低。轻压下时铸坯宽度1/2、1/4位置处的中心疏松体积分别为1.73×10-7、2.68×10-7 cm3/g;大压下15 mm时铸坯宽度1/2、1/4位置处的中心疏松体积分别为5.33×10-8、-1.84×10-8cm3/g。轻压下、大压下15 mm时连铸坯中心碳偏析均较轻,但后者相对稍重,最大值分别为1.176、1.282;轻压下与大压下条件下,铸坯宽度1/4位置中心碳偏析均高于宽度1/2位置。特别地,大压下15 mm时,铸坯宽度1/2位置、1/4位置处,连铸坯中心靠外弧侧出现负偏析,最大负偏析值为0.916。

Improvement of internal quality for continuous casting slab by heavy reduction at solidification endpoint

The influence of the heavy reduction of the single-roller solidification end on the internal quality of continuous casting slab was discussed. The microstructure of Q345D continuous casting slab under different drawing speeds was analyzed and the quantitative measurement of the porosity of the slab center was carried out. The results showed that the internal quality of the continuous casting slab can be effectively improved by using heavy reduction. When the pulling speed was 0.70 m/min, the center porosity volume was significantly reduced at a 1/2 position and a 1/4 position of the slab width when the heavy reduction was 15 mm. The center porosity volume at the 1/2 and 1/4 position of the slab width on the condition of soft reduction was 1.73×10-7 cm3/g and 2.68×10-7 cm3/g, respectively. The center porosity volume at the 1/2 and 1/4 positions of the slab width at a heavy reduction of 15 mm was 5.33×10-8 cm3/g and -1.84×10-8 cm3/g, respectively. Under the soft reduction, the maximum value of center carbon segregation was 1.176, and under the heavy reduction of 15 mm, the maximum value of center carbon segregation was 1.282. A slight negative segregation occurred at 15 mm under a heavy reduction, and the maximum negative segregation value was 0.916.