低碳钢连铸方坯角部横裂形成分析和控制工艺

Analysis on Formation of Transverse Crack at Corner of Concasting Bloom of Low Carbon Steel and Control Technology

兴澄特钢300mm×320mm低碳钢铸坯酸洗后,可观察到铸坯角部振痕波谷处的横向裂纹,其长度为10～30mm,最大宽度达2mm。生产实践表明,当SA-210系列锅炉钢(%:0.13～0.25C、0.45～1.10Mn)的[Alt]从0.009%增加至0.021%时,铸坯角部横裂纹指数从0.03增加到2.64。因微量钛能改善钢在较低变形速率下的热成型性,钢中加微量钛,可以明显减少铸坯角部横裂纹的产生。通过控制加Al量使[Alt]≤0.010%,加Ti使[Ti]≈0.02%,同时采用提高钢水流动性和铸坯矫直温度≥900℃等措施,避免了SA-210C钢的铸坯角部横裂纹的产生。

The transverse cracks with length 10 ～ 30 mm and maximum wide 2 mm at billet comer vibrating mark trough of pickled 300 mm × 320 mm low carbon steel cast bloom produced at Xingcheng special Steel were observed. The production practice indicated that as [ Alt ] of SA-210 series steel for boiler （0.13 ～ 0. 25C, 0.45 ～ 1.10Mn） increased from 0. 009% to 0. 021% the index of transverse crack at comer of casting bloom increased from 0. 03 to 2. 64, while with adding micro titanium in steel the transverse crack at comer of casting bloom decreased obviously as micro titanium is available to improve hot forming ability of steel at lower deformation rate. The formation of transverse crack at comer of casting bloom of SA-210C steel was avoided by control adding Al amount to ensure [ Alt ]≤0. 010%, adding Ti to get about 0. 02% [ Ti ], and adopting the operation measures such as to increase molten steel flowability and cast bloom straightening temperature ≥900℃.