对含Si低碳钢连铸坯发生的横向断裂缺陷进行了金相、扫描电镜检验分析及加热工艺模拟试验；对铸坯从钢水凝固到轧前加热断裂的热历程中所受外力及其与裂纹形成的关系进行了分析。检验分析结果表明：引起铸坯横向断裂的主要原因是浇注时钢水过热度高，凝固组织冷却慢，晶粒发生了严重的粗化，柱状晶间界的强度大大降低，使铸坯在弯曲矫直过程中形成内部裂纹，当再加热时，其热应力使内部裂纹进一步扩展而开裂。所以，控制好铸坯的浇注温度，提高铸坯中心等轴晶率，是防止含硅低碳钢连铸坯横向断裂的有效途径。
The inspection and analysis and the process thermal simulation test have been made by using metallographic microscope and SEM on the failure of transverse rupture in the containing silicon low carbon steel billets after continuous casting. The continuous casting billet bearing internal and external forces and their dependence with crack growth have been analyzed in the whole thermal process from liquid steel solidification to rupture as heating before rolling. The result indicates that the failure is mainly owing to the higher degree of superheat of cast molten steel, the slower cooling rate of solidified structure, and thus the serious coarsening grains were got, the greatly decreased strength of columnar crystal boundary, thus internal cracks during the process of reeling and curving of billet were formed. When reheating, the thermal stress makes the internal cracks sustainedly expanded and finally rupture. Therefore the most effective way to prevent billet from transverse rupture is to adjust the casting temperature of the containing silicon low carbon steel billet to a proper degree, so as to enhance the center equiaxed grain rate in the solidified structure.
参考文献
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%