连铸板坯内部裂纹的形成机制及控制实践
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摘要
通过对连铸坯内裂纹的形貌、形成机制的系统性概括与分析,发现其内裂纹的产生主要有两方面的原因:(1)设备因素:辊子间距、变形、弯曲以及矫直方法等(;2)操作因素:浇铸速度、二次冷却强度以及P、S等元素的浓化等。而减少连铸坯内部裂纹的发生机率,需要采取措施使作用于铸坯上应力的总和达到最小程度,尤其要控制好连铸坯鼓肚。据此,提出了维护好连铸机的设备功能精度、减少连铸坯鼓肚量、坯壳凝固前沿所受的各种机械应力的方法,以减少连铸坯内裂纹的产生。综上所述,依据连铸坯凝固收缩原理和凝固末端轻压下原理而开发的动态轻压下技术或静态辊缝收缩控制技术是控制连铸坯内部裂纹最经济、最有效的措施。
In the present work,the morphologies and formation mechanism of inner cracks of continuous casting slab were systematically generalized and investigated. It was found that the formation of inner cracks could be ascribed to two primary reasons:(1)apparatus issues:roller spacing,deformation,bending and straightening method and casting speed etc.(2)controlling issues:casting speed,secondary cooling intensity and thickening of P and S etc. Besides,to reduce the possibility of inner cracks formation,measures should be taken to minimize the whole casting stress,especially to control the bulge of continuous casting slab. Based on the fact,it was suggested that maintaince of the accuracy of continuous casting machine,reduction of the bulging capacity as well as various mechanical stress forced on the shell before solidification to reduce the formation of inner cracks. In summary,the dynamic soft reduction technology which is based on the solidification and shrinkage principle or static roll gap shrinkage technology can be regarded as the most cost-effective measures to control the inner cracks of continuous casting slab.
In the present work,the morphologies and formation mechanism of inner cracks of continuous casting slab were systematically generalized and investigated. It was found that the formation of inner cracks could be ascribed to two primary reasons:(1)apparatus issues:roller spacing,deformation,bending and straightening method and casting speed etc.(2)controlling issues:casting speed,secondary cooling intensity and thickening of P and S etc. Besides,to reduce the possibility of inner cracks formation,measures should be taken to minimize the whole casting stress,especially to control the bulge of continuous casting slab. Based on the fact,it was suggested that maintaince of the accuracy of continuous casting machine,reduction of the bulging capacity as well as various mechanical stress forced on the shell before solidification to reduce the formation of inner cracks. In summary,the dynamic soft reduction technology which is based on the solidification and shrinkage principle or static roll gap shrinkage technology can be regarded as the most cost-effective measures to control the inner cracks of continuous casting slab.
引文
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[14]曾全胜,蒋云云,隋然.连铸钢板坯凝固壳横截面变形与内部裂纹的关系[J].理化检验(物理分册),2003,39(6):290.
[15]王保东,孙吉才.板坯内部裂纹成因分析与对策[J].连铸,2008(6):39.
[16]汪洪峰.连铸板坯角横裂纹的形成机理及控制措施[J].连铸,2015,1(1):61.
[2] Birat J P,Marchionni C. Continuous casting-past,present and future[J]. Revue De Métallurgie,2006,102(6):441.
[3] Grimm B,Andrzejewski P,Müller K,et al. Inclusions in continuously cast steel slabs-numerical model and validation[J]. Steel Research,2016,70(10):420.
[4] Yong C,Hong P,Guo-Rong W U. Quality control for continuously cast slab of high strength weathering steel Q450NQR1[J].Journal of Iron and Steel Research(International),2011(S1):557.
[5] Zhong H,Chen X,Han Q,et al. A thermal simulation method for solidification process of steel slab in continuous casting[J].Metallurgical and Materials Transactions B,2016,47(5):2963.
[6] Choudhary S K,Ganguly S,Sengupta A,et al. Solidification morphology and segregation in continuously cast steel slab[J].Journal of Materials Processing Technology,2017,243:312.
[7]汤伟,孟令涛,孙利斌,等. Q235B钢连铸板坯中间裂纹成因分析及改进措施[J].连铸,2017,42(5):59.
[8]张帆,胡兵.板坯三角区裂纹的产生及控制[J].连铸,1999(2):21.
[9]张富强,李超,姜振生,等.连铸板坯中心裂纹和三角区裂纹的成因及防止[J].钢铁,2004,39(10):20.
[10]赵晶,王臻明,王国连,等. 400 mm特厚板坯尾坯浇铸工艺的研究[J].连铸,2019,44(1):1.
[11]韩志强,蔡开科.连铸坯内裂纹形成条件的评述[J].钢铁研究学报,2001,13(1):68.
[12]贺景春,陈建军,梁志刚.连铸坯裂纹主要影响因素及对策研究[J].包钢科技,2004,30(5):8.
[13]中田博士,井上正,稻积透,等.高强度热轧钢板及其制造方法[P]. CN 1322256 A.
[14]曾全胜,蒋云云,隋然.连铸钢板坯凝固壳横截面变形与内部裂纹的关系[J].理化检验(物理分册),2003,39(6):290.
[15]王保东,孙吉才.板坯内部裂纹成因分析与对策[J].连铸,2008(6):39.
[16]汪洪峰.连铸板坯角横裂纹的形成机理及控制措施[J].连铸,2015,1(1):61.