45钢连铸大方坯中心疏松与缩孔控制
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摘要
针对360 mm×450 mm断面的45钢连铸坯中心疏松和缩孔导致轧制后圆钢探伤不合格的问题,开展了拉速与二冷水对比试验、凝固末端电磁搅拌对比试验以及重压下压下辊辊型对比试验,采用低倍酸洗、原位分析和真密度分析了试验铸坯和轧制后圆钢质量。试验结果表明,采用拉速0.45 m/min、二冷采用中冷、凝固末端电磁搅拌采用300 A/2.4 Hz时有利于铸坯扩大铸坯等轴晶区,铸坯等轴晶区最大为280 mm×170 mm。重压下采用凸形辊生产的铸坯中心真密度为8.022 6 g/cm~3,致密度为0.998 4,高于平辊重压下。综合技术应用后,累计生产45圆钢2 583 t,45圆钢探伤合格率从70.85%提高到95.87%。
In order to reduce the rate of flaw detection disqualification in 45 round steel with diameters from ?200 mm to ?250 mm which was rolled in 360 mm×450 mm bloom. The main causes of flaw detection disqualification were center segregation and porosity of blooms. The casting speed,secondary cooling water and electromagnetic stirring at end of solidification were contrast tested. The roller of heavy reduction was optimized. Microscopy,scanning spectrometer and true density of the blooms were analyzed. The results show that the 0.45 m/min casting speed and low secondary cooling water with 300 A and 2.4 Hz parameters of electromagnetic stirring were benefit to the equiaxed grains expanding. The biggest area of equiaxed grains was 280 mm×170 mm.The true density and compactness of bloom with convex roller were 8.022 6 g/cm~3 and 0.998 4 respectively which was higher than that in flat roller. After comprehensive technology application,the qualification rate of flaw detection was improved form from 70.85% to 95.87% in 2 583 tons 45 round steel production.
In order to reduce the rate of flaw detection disqualification in 45 round steel with diameters from ?200 mm to ?250 mm which was rolled in 360 mm×450 mm bloom. The main causes of flaw detection disqualification were center segregation and porosity of blooms. The casting speed,secondary cooling water and electromagnetic stirring at end of solidification were contrast tested. The roller of heavy reduction was optimized. Microscopy,scanning spectrometer and true density of the blooms were analyzed. The results show that the 0.45 m/min casting speed and low secondary cooling water with 300 A and 2.4 Hz parameters of electromagnetic stirring were benefit to the equiaxed grains expanding. The biggest area of equiaxed grains was 280 mm×170 mm.The true density and compactness of bloom with convex roller were 8.022 6 g/cm~3 and 0.998 4 respectively which was higher than that in flat roller. After comprehensive technology application,the qualification rate of flaw detection was improved form from 70.85% to 95.87% in 2 583 tons 45 round steel production.
引文
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[14]杨晓江.唐钢薄板坯连铸高碳钢65Mn的质量控制[J].中国冶金,2016,26(12):36.(YANG Xiao-jiang.Quality control of65Mn thin slab casting high-carbon steel in Tangsteel[J].China Metallurgy,2016,26(12):36.)
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[16]朱苗勇,祭程.连铸大方坯凝固末端重压下技术及其应用[C]//第六届宝钢学术年会论文集.上海:宝钢,2015.(ZHU Miao-yong,JI Cheng.Heavy reduction technology and its application for bloom continuous casting process[C]//The 6th Bao Steel Academic Essays.Shang Hai:Baosteel,2015.)
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[18]陈亮,宋波,陈天明,等.320 mm×410 mm大方坯连铸重轨钢质量改进与应用[J].钢铁,2017,52(4):37.(CHEN Liang,SONG Bo,CHEN Tian-ming,et al.Inner quality improvement and application of 320 mm×410 mm bloom in continuous casting of railway steel[J].Iron and Steel,2017,52(4):37.)
[19]邹冰梅.中心偏析与中心疏松的形成与预防[J].钢铁技术,2005(2):1.(ZOU Bing-mei.Formation and prevention of center segregation and center porosity[J].Technology of Iron and Steel,2005(2):1.)
[20]刘宝喜,高彩茹,郑文超,等.高韧性桥梁钢Q420q D的开发[J].中国冶金,2018,28(2):67.(LIU Bao-xi,GAO Cai-ru,ZHENG Wen-chao,et al.Development of Q420q D bridge steel with high toughness[J].China Metallurgy,2018,28(2):67.)
[2]欧海龙,金林奎,黄持伟,等.45钢法兰调质处理开裂原因分析[J].理化检验:物理分册,2017,53(7):528.(OU Hai-long,JIN Lin-kui,HUANG Chi-wei,et al.Reason analysis on cracking of a 45 steel flange after quenching and tempering treatment[J].Physical Test and Chemical Analyze(Part A:Phys Test),2017,53(7):528.)
[3]王长健.45钢锥套淬火裂纹失效分析[J].金属热处理,2017,42(4):204.(WANG Chang-jian.Failure analysis on quenching cracks of 45 steel taper sleeve[J].Heat Treatment of Metals,2017,42(4):204.)
[4]张瑜,徐勇,吴军,等.45钢轴的疲劳断裂分析[J].失效分析与预防,2017,12(2):126.(ZHANG Yu,XU Yong,WU Jun,et al.Fatigue fracture analysis of 45 steel shaft[J].Failure Analysis and Prevention,2017,12(2):126.)
[5]储鸿文,留津津,金进文,等.45钢连铸矩形坯中心疏松和缩孔的研究[J].炼钢,2011,27(3):60.(CHU Hong-wen,LIU Jin-jin,JIN Jin-wen,et al.Study on center porosities and shrinkage cavities of rectangular blooms in continuous casting of 45steel[J].Steelmaking,2011,27(3):60.)
[6]朱施利,郑国渠,叶健松,等.二冷喷淋强度对连铸坯凝固组织的影响[J].钢铁,2014,49(8):48.(ZHU Shi-li,ZHENG Guo-qu,YE Jian-song,et al.Influence of spraying intensity on solidification structure of continuous casting billet during secondary cooling[J].Iron and Steel,2014,49(8):48.)
[7]贾燕璐,苗锋,赵文成.末端电磁搅拌对?400 mm铸坯碳偏析的影响[J].热加工工艺,2012,41(7):65.(JIA Yan-lu,MIAO Feng,ZHAO Wen-cheng.Effects of F-EMS on carbon content segregation in?400 mm round billets[J].Casting Forging Welding,2012,41(7):65.)
[8]王晓东,王宝峰,曹建刚,等.大方坯末端电磁搅拌位置和连铸工艺参数的确定[J].钢铁,2011,46(8):47.(WANG Xiaodong,WANG Bao-feng,CAO Jian-gang,et al.Determination of F-EMS position and process parameters in bloom continuous caster[J].Iron and Steel,2011,46(8):47.)
[9]王彪,谢植,贾光霖,等.凝固末端电磁搅拌参数确定及其对中心偏析的影响[J].钢铁,2007,42(3):18.(WANG Biao,XIE Zhi,JIA Guang-lin,et al.Parameter determination and effects on center segregation of F-EMS[J].Iron and Steel,2007,42(3):18.)
[10]曾杰,张森林,刘澄,等.高碳钢矩形坯凝固末端永磁搅拌试验[J].钢铁,2016,51(7):22.(ZENG Jie,ZHANG Sen-lin,LIU Cheng,et al.Final permanent magnet stirring in high carbon rectangular billet continuous casting[J].Iron and Steel,2016,51(7):22.)
[11]朱惠刚,缪新德,陶建军,等.连铸方坯末端电磁搅拌工艺实践[J].连铸,2007,61(6):35.(ZHU Hui-gang,MIAO Xin-de,TAO Jian-jun,et al.Practice on F-EMS at a bloom caster[J].Continuous Casting,2007,61(6):35.)
[12]刘伟,刘浏,何平,等.凝固传热模型在静态轻压下技术中的应用[J].钢铁,2010,45(1):32.(LIU Wei,LIU liu,HE Ping,et al.Application of solidification model to static soft reduction[J].Iron and Steel,2010,45(1):32.)
[13]董鹏莉,尚海霞,王华.铸坯及板卷典型质量缺陷成因与控制技术[J].中国冶金,2017,27(6):7.(DONG Peng-li,SHANG Hai-xia,WANG Hua.Typical quality defect cause and control technology of slab and plate[J].China Metallurgy,2017,27(6):7.)
[14]杨晓江.唐钢薄板坯连铸高碳钢65Mn的质量控制[J].中国冶金,2016,26(12):36.(YANG Xiao-jiang.Quality control of65Mn thin slab casting high-carbon steel in Tangsteel[J].China Metallurgy,2016,26(12):36.)
[15]江中块,蔡兆镇,牛振宇,等.1 650板坯压下过程热/力学行为及压下工艺优化[J].中国冶金,2017,27(7):22.(JIANG Zhong-kuai,CAI Zhao-zhen,NIU Zhen-yu,et al.Thermo-mechanical behavior of 1 650 slab during soft reduction and optimization of soft reduction process[J].China Metallurgy,2017,27(7):22.)
[16]朱苗勇,祭程.连铸大方坯凝固末端重压下技术及其应用[C]//第六届宝钢学术年会论文集.上海:宝钢,2015.(ZHU Miao-yong,JI Cheng.Heavy reduction technology and its application for bloom continuous casting process[C]//The 6th Bao Steel Academic Essays.Shang Hai:Baosteel,2015.)
[17]王博.重压下铸坯制过程中内部缺陷演变行为的研究[D].北京:北京科技大学,2017.(WANG Bo.Research on Evolution Behavior of Internal Defects in Heavy Reduction Slab During the Rolling Process[D].Beijing:University of Science and Technology,2017.)
[18]陈亮,宋波,陈天明,等.320 mm×410 mm大方坯连铸重轨钢质量改进与应用[J].钢铁,2017,52(4):37.(CHEN Liang,SONG Bo,CHEN Tian-ming,et al.Inner quality improvement and application of 320 mm×410 mm bloom in continuous casting of railway steel[J].Iron and Steel,2017,52(4):37.)
[19]邹冰梅.中心偏析与中心疏松的形成与预防[J].钢铁技术,2005(2):1.(ZOU Bing-mei.Formation and prevention of center segregation and center porosity[J].Technology of Iron and Steel,2005(2):1.)
[20]刘宝喜,高彩茹,郑文超,等.高韧性桥梁钢Q420q D的开发[J].中国冶金,2018,28(2):67.(LIU Bao-xi,GAO Cai-ru,ZHENG Wen-chao,et al.Development of Q420q D bridge steel with high toughness[J].China Metallurgy,2018,28(2):67.)