组织结构及夹杂物对高强结构厚板冷弯开裂影响的研究
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摘要
冷弯开裂一直是制约高强度结构厚板应用的关键,其影响因素较多。实验对Q690D厚板冷弯开裂原因开展了深入分析。通过金相组织分析发现厚板表面存在1层100μm左右、由粗大贝氏体和细晶铁素体所组成的带状组织是导致钢板冷弯开裂的主要原因。此外,对试验钢中氧、氮、氢含量进行化学检测,发现氧含量超标,且通过扫描电镜及能谱观察发现钢中存在较多氧化镁、氧化铝类夹杂,评级为D类和DS类1.0级。据此,提出增加试验钢中硅元素的含量,可以有效抑制锰元素偏聚造成的带状组织,同时可降低钢中的氧化物夹杂。
Cold bending cracking was always the key to restrict the application of high strength structural thick plate,and there were many influencing factors.The reasons for cold bending cracking of Q690 Dthick plate were deeply analyzed.The metallographic structure analysis showed that a layer of banded structure(about 100μm,which was composed of coarse bainite and fine grain ferrite)on the surface of thick plate was the main reason to cause cold bending cracking of steel plate.In addition,the content of oxygen,nitrogen and hydrogen in the tested steel was detected by chemical method.It was found that the content of oxygen exceeded the standard.The scanning electron microscope(SEM)observation and energy spectrum analysis indicated that many magnesium oxide and aluminum oxide inclusions existed in steel.The grade was Level 1.0 of Class D and Class DS.Therefore,it was proposed to enhance the content of silicon in the tested steel to effectively inhibit the banded structure caused due to the segregation of manganese.Meanwhile,the oxide inclusions in steel could be also reduced.
Cold bending cracking was always the key to restrict the application of high strength structural thick plate,and there were many influencing factors.The reasons for cold bending cracking of Q690 Dthick plate were deeply analyzed.The metallographic structure analysis showed that a layer of banded structure(about 100μm,which was composed of coarse bainite and fine grain ferrite)on the surface of thick plate was the main reason to cause cold bending cracking of steel plate.In addition,the content of oxygen,nitrogen and hydrogen in the tested steel was detected by chemical method.It was found that the content of oxygen exceeded the standard.The scanning electron microscope(SEM)observation and energy spectrum analysis indicated that many magnesium oxide and aluminum oxide inclusions existed in steel.The grade was Level 1.0 of Class D and Class DS.Therefore,it was proposed to enhance the content of silicon in the tested steel to effectively inhibit the banded structure caused due to the segregation of manganese.Meanwhile,the oxide inclusions in steel could be also reduced.
引文
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[3]赵伟,孔小东,甘众远,等.SPA-H钢冷弯开裂研究及工艺改进[J].金属材料与冶金工程,2016,44(1):37-40.ZHAO Wei,KONG Xiao-dong,GAN Zhong-yuan,et al.Research on cold bending cracking and improving methods of SPA-H steels[J].Metal Materials and Metallurgy Engineering,2016,44(1):37-40.
[4]郭亚婷,王福明,黄泉金,等.510L汽车大梁钢冷弯开裂研究[J].金属热处理,2015,40(6):190-194.GUO Ya-ting,WANG Fu-ming,HUANG Quan-jin,et al.Cold bending cracking of 510Lsteel automobile beam[J].Heat Treatment of Metals,2015,40(6):190-194.
[5]肖广耀,宋进英,田亚强,等.硫化物夹杂及成分偏析对610L钢冷弯开裂的影响[J].河北联合大学学报,2012,34(3):71-74.XIAO Guang-yao,SONG Jin-ying,TIAN Ya-qiang,et al.Segregation and sulphide inclusions influence on cracking of cold-formed for 610L[J].Journal of Hebei United University,2012,34(3):71-74.
[6]申少华,刘国林,韦玄,等.中厚钢板中的硫化物夹杂及其对冷弯性能的影响[J].宽厚板,2005,11(2):26-29.SHEN Shao-hua,LIU Guo-lin,WEI Xuan,et al.Sulfide inclusion in medium and heavy plate and its effect on cold bending properties[J].Wide and Heavy Plate,2005,11(2):26-29.
[7]衣海龙,宋勇军,徐兆国,等.TT610L大梁钢冷弯裂纹原因分析[J].东北大学学报:自然科学版,2010,31(6):812-815.YI Hai-long,SONG Yong-jun,XU Zhao-guo,et al.Causal analysis of cold bending cracks of TT610Lsteel plates for chassis frames[J].Journal of Northeastern University:Natural Science,2010,31(6):812-815.
[8]焦安杰,薛俊峰,陈静.汽车大梁钢610L折弯层状开裂原因分析[J].物理测试,2018,4(2):35-38.JIAO An-jie,XUE Jun-feng,CHEN Jing.Cause analysis of lamellar cracking of automobile beam steel 610Lduring bending[J].Physics Examination and Testing,2018,4(2):35-38.
[9]LIU X,LU Z X,CHEN Y,et al.Failure assessment for the high-strength pipelines with constant-depth circumferential surface cracks[J].Advances in Materials Science and Engineering,2018,5(14):514-518.
[10]万荣春,付立铭,王学双,等.980MPa级汽车薄板钢拉深冲杯延迟开裂性能的研究[J].热加工工艺,2017,46(3):54-56.WAN Rong-chun,FU Li-ming,WANG Xue-shuang,et al.Study on deep drawing delayed fracture properties of980MPa steel thin sheets for automotive[J].Hot Working Technology,2017,46(3):54-56.
[11]赵楠,穆海玲,周丽萍.BM510汽车大梁钢冷弯开裂原因分析[J].机械工程材料,2008,32(11):72-75.ZHAO Nan,MU Hai-ling,ZHOU Li-ping.Cold bending cracking analysis of BM510steel plates for automobile frames[J].Materials for Mechanical Engineering,2008,32(11):72-75.
[12]Ogawa T,Koyama M,Nishikura Y,et al.Fatigue behavior of Fe-Cr-Ni-based metastable austenitic steels with an identical tensile strength and different solute carbon contents[J].Tetsu to Hagane-Journal of the Iron and Steel Institute of Japan,2018,104(2):88-97.