双相变回温温度对钢组织及其热塑性的影响

doi:10.13228/j.boyuan.issn0449-749x.20220423

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Abstract Continuous casting of Nb-bearing steels is easy to produce transverse cracks on slab corners. Applying a cyclic phase transformation cooling process(γ→α→γ),which can greatly improve the structure ductility of steel at high temperature,to the slab corners during continuous casting,the cracks could be greatly reduced. As one of most important parameters,the returning temperature at the stage of α→γ phase transformation is an important factor affecting the applying effect of the process. In the present work,the detection methods,such as Gleeble thermal simulation,OM,TEM,as well as the fracture scanning are used to analyze the micro-structure evolution and plasticity of a Q345D-Nb steel under the different returning temperatures of the cyclic phase transformation cooling process. The results showed that the austenite grains would not be refined at the returning temperature of 850 ℃. The average size of the grains was about 502.2 μm,which was similar to that of the conventional cooling process. When the returning temperature rose to 900 ℃,the austenite showed mixed growth. When the returning temperature rose to 950 ℃,the grain size was refined to 61.2 μm. When the returning temperature rose to 1 000 ℃,the austenite grain coarsely grew. The average size of austenite grains increased 38.07 % compared with that of the returning temperature to 950 ℃. Under the conventional cooling process and the cyclic phase transformation cooling process at the returning temperature of 850,900,950 and 1 000 ℃,respectively,the minimum reduction of area (RA) at the temperature range of 700-900 ℃ were 29.6%,45.0%,56.3%,68.2%,and 63.2%. Under the conventional cooling process,the thickness of ferrite film at grain boundary of the steel at 750 ℃ was 20-25 μm,and the carbonitride precipitated with large size and chain structure distribution,and the fracture mode was intergranular brittle fracture. At the same tensile fracture temperature,the thickness of ferrite film of austenite grain boundary under the cyclic phase transformation cooling process decreased to 5-10 μm,and the carbonitride precipitates dispersedly and finely. The fracture mode transforms to the plastic fracture gradually. The plasticity was significantly improved. Applying the cyclic phase transformation cooling process to the practice,the average grain sizes of austenite at the depths of 5 mm and 10 mm below the corner of slab were refined to 186 μm and 362 μm,which increased the ability of slab to resist cracks.

Key words： micro-alloyed steel returning temperature transverse corner crack cyclic phase transformation grain refinement carbonitride precipitation

Received: 16 June 2022

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	CHENG Biao
	CAI Zhao-zhen
	AN Jia-zhi
	ZHU Miao-yong

Cite this article:

CHENG Biao,CAI Zhao-zhen,AN Jia-zhi等. Effect of cyclic phase transformation cooling process at returning temperature on microstructure and plasticity of steels[J]. Iron and Steel, 2023, 58(1): 67-77.

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http://www.chinamet.cn/Jweb_gt/EN/10.13228/j.boyuan.issn0449-749x.20220423 OR http://www.chinamet.cn/Jweb_gt/EN/Y2023/V58/I1/67

[1] 韩荣,刘洪喜,尉文超,等. Ti-V-Mo微合金化22MnB5钢中析出相及其强化作用[J]. 钢铁,2022,57(2):127.(HAN Rong,LIU Hong-xi,WEI Wen-chao,et al. Precipitates and their strengthening in Ti-V-Mo microalloyed 22MnB5 steel[J]. Iron and Steel,2022,57(2):127.)
[2] 张朝磊,邵洙浩,李戬,等. 铌微合金化技术在中高碳钢中的应用现状与发展[J]. 材料导报,2021,35(5):5102.(ZHANG Chao-lei,SHAO Zhu-hao,LI Jian,et al. Application and development of niobium microalloying technology in medium and high carbon steel[J]. Materials Reports,2021,35(5):5102.)
[3] XU Li-jun,ZHANG Shu-lan,QIU Chun-gen,et al. Surface microstructure control of microalloyed steel during slab casting[J]. Journal of Iron and Steel Research, International,2017,24(8):803.
[4] 宋扬,刘丽华,张中武. 钛微合金化低碳钢的研究进展[J]. 材料导报,2021,35(15):15175.(SONG Yang,LIU Li-hua,ZHANG Zhong-wu. Research progress on the titanium microalloyed low carbon steels[J]. Materials Reports,2021,35(15):15175.)
[5] 张剑君,张慧,席常锁,等. 薄板坯连铸中碳钢角横裂缺陷成因及控制[J]. 钢铁,2017,52(11):32.(ZHANG Jian-jun,ZHANG Hui,XI Chang-suo,et al. Analysis and control of transverse corner cracking formation on middle carbon steel in thin slab casting[J]. Iron and Steel,2017,52(11):32.)
[6] 唐萍,罗琳青,文光华,等. 基于激光共聚焦显微镜模拟微合金钢连铸过程中第二相的析出行为[J]. 工程科学学报,2015,37(9):1130.(TANG Ping,LUO Lin-qing,WEN Guang-hua,et al. Precipitation behaviors of secondary phases in micro-alloy steels during continuous casting simulated by CLSM[J]. Chinese Journal of Engineering,2015,37(9):1130.)
[7] QU Tian-peng,TIAN Jun,CHEN Kai-lai,et al. Precipitation behaviour of TiN in Nb-Ti containing alloyed steel during the solidification process[J]. Ironmaking and Steelmaking,2019,46(4):353.
[8] 田星,朱国明,康永林,等. CSP 流程钛微合金化高强钢的第二相粒子析出行为[J]. 工程科学学报,2015,37(1):42.(TIAN Xing,ZHU Guo-ming,KANG Yong-lin,et al. Precipitation behavior of Ti-microalloyed high-strength steel by CSP process[J]. Chinese Journal of Engineering,2015,37(1):42.)
[9] YANG Gai-yan,ZHU Li-guang,CHENG Wei,et al. Initiation of surface cracks on beam blank in the mold during continuous casting[J]. Metals,2018,8(9):712.
[10] NIU Zhen-yu,CAI Zhao-zhen,ZHU Miao-yong. Effect of mold cavity design on the thermomechanical behavior of solidifying shell during microalloyed steel slab continuous casting[J]. Metallurgical and Materials Transactions B,2021,52(3):1556.
[11] ZENG Ya-nan,FENG Qian,LI Jun-guo,et al. Effect of the microstructure on the crack initiation during thermal cycling of Nb-Ti-bearing continuous casting slabs[J]. Ironmaking and Steelmaking,2021,48(4):370.
[12] 马静超. 板坯非正常角部横裂纹产生原因分析[J]. 中国冶金,2021,31(6):77.(MA Jing-chao. Analysis of abnormal transverse corner crack in slab[J]. China Metallurgy,2021,31(6):77.)
[13] WANG Ya-dong,REN Qing,ZHANG Li-feng,et al. Formation and control of transverse corner cracks in the continuous casting slab of a microalloyed steel[J]. Steel Research International,2021,92(6):2000649.
[14] 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.(ZHANG Fu-qiang,LI Chao,JIANG Zhen-sheng,et al. Formation mechanism and prevention of centerline and triangle-zone cracking in continuous cast slabs[J]. Iron and Steel,2004,39(10):20.)
[15] Scheller P R,Lachmann S,Klinkenberg C. Nb-alloyed Cr-steel in simulated strip casting process[J]. ISIJ International,2007,46(12):1865.
[16] Umemoto M,Hai Guo Z,Tamura I. Effect of cooling rate on grain size of ferrite in a carbon steel[J]. Materials Science and Technology,1987,3(4):249.
[17] MA Fan-jun,WEN Guang-hua,TANG Ping,et al. In situ observation and investigation of effect of cooling rate on slab surface microstructure evolution in microalloyed steel[J]. Ironmaking and Steelmaking,2010,37(3):211.
[18] Grange R A. Strengthening steel by austenite grain refinement[J]. ASM Trans Quart,1966,59(1):26.
[19] Schmidt L,Josefsson A. On the formation and avoidance of transverse cracks in continuously cast slabs from curved mould machines[J]. Scandinavian Journal of Metallurgy,1974,3(1):193.
[20] Sagaradze V V. An ultrafine grain structure formed as a result of cyclic γ→α→γ transformations[J]. Nanostructured Materials,1997,9(1):201.
[21] Kato T,Ito Y,Kawamoto M,et al. Prevention of slab surface transverse cracking by microstructure control[J]. ISIJ International,2003,43(11):1742.
[22] Ito Y,Kato T,Yamanaka A,et al. Improvement of hot ductility in continuously cast strand by ferrite precipitation control[J]. Tetsu-to-Hagane,2003,89(10):1023.
[23] Lee U H,Park T E. Assessment of hot ductility with various thermal histories as an alternative method of situ solidification[J]. ISIJ International,2010,20(4):540.
[24] 郭军力,文光华,符姣姣,等. 冷却速率对包晶钢凝固过程中包晶转变收缩的影响[J]. 金属学报,2019,55(10):1311.(GUO Jun-li,WEN Guang-hua,FU Jiao-jiao,et al. Influence of cooling rate on the contraction of periectic transformation during solidification of peritectic steels[J]. Acta Metallurgical Sinica,2019,55(10):1311.)
[25] 兰鹏,杜辰伟,陈培莉,等. 微合金钢连铸表面横裂纹形成机理与控制技术研究现状[J]. 钢铁研究学报,2017,29(1):1.(LAN Peng,DU Chen-wei,CHEN Pei-li,et al. Research status of surface transverse cracking formation mechanism and control technique for continuously cast microalloyed steels[J]. Journal of Iron and Steel Research,2017,29(1):1.)
[26] 袁航,杨树峰,王田田,等. 亚包晶微合金钢连铸板坯角部横裂纹研究进展[J]. 中国冶金,2020,30(10):1.(YUAN Hang,YANG Shu-feng,WANG Tian-tian,et al. Research progress of transverse crack at corner on hypo-peritectic micro-alloyed steel slab[J]. China Metallurgy,2020,30(10):1.)
[27] 蔡兆镇,安家志,刘志远,等. 微合金钢连铸坯角部裂纹控制技术研发及应用[J]. 钢铁研究学报,2019,31(2):117.(CAI Zhao-zhen,AN Jia-zhi,LIU Zhi-yuan,et al. Research on development and application of micro-alloyed steel slab corner transversal crack control technology[J]. Journal of Iron and Steel Research,2019,31(2):117.)
[28] 刘志远,王重君,蔡兆镇,等. 含铌微合金钢连铸坯角部裂纹控制二冷新工艺[J]. 中国冶金,2018,28(3):22.(LIU Zhi-yuan,WANG Chong-jun,CAI Zhao-zhen,et al. New secondary cooling process for transverse corner crack control of Nb micro-alloyed steel slab[J]. China Metallurgy,2018,28(3):22.)
[29] 陈登福,徐佩,龙木军,等. 钢液连铸二次冷却先进工艺模型的发展与研究[J]. 钢铁,2020,55(3):40.(CHEN Deng-fu,XU Pei,LONG Mu-jun,et al. Development and investigation of advanced process model for secondary cooling in continuous of molten steel[J]. Iron and Steel,2020,55(3):40.)
[30] 郑宏光,刘华松. 铸态奥氏体晶粒粗化与热装再加热中晶粒的演化[J]. 连铸,2020,45(2):45.(ZHENG Hong-guang,LIU Hua-song. Grain coarsening of as-cast austenite and evolution of grain structure during hot charging reheating[J]. Continuous Casting,2020,45(2):45.)
[31] 杜肖臣,刘青,张江山,等. 喷淋水量分布对C38 N2钢大方坯冷却效果的影响[J]. 中国冶金,2022,32(5):93.(DU Xiao-chen,LIU Qing,ZHANG Jiang-shan,et al. Influence of spray water distribution on cooling effect of C38 N2 bloom[J]. China Metallurgy,2022,32(5):93.)
[32] 王海宝,张炯明,赵新宇,等. 冷却模式对铸坯表面组织的影响[J]. 钢铁,2013,48(4):35.(WANG Hai-bao,ZHANG Jiong-ming,ZHAO Xin-yu,et al. Effect of cooling pattern on surface microstructure of slab[J]. Iron and Steel,2013,48(4):35.)
[33] DU C,ZHANG J,WEN J,et al. Hot ductility trough elimination through single cycle of intense cooling and reheating for microalloyed steel casting[J]. Ironmaking and Steelmaking,2016,43(5):331.
[34] Maehara Y,Yasumoto K,Tomono H,et al. Surface cracking mechanism of continuously cast low carbon low alloy steel slabs[J]. Materials Science and Technology,1990,6(9):793.
[35] 杨壹,郑志斌,叶志国,等. 轻质高锰钢的组织及力学性能[J]. 钢铁研究学报,2021,33(11):1189.(YANG Yi,ZHENG Zhi-bin,YE Zhi-guo,et al. Microstructure and mechanical properties of lightweight high manganese steel[J]. Journal of Iron and Steel Research,2021,33(11):1189.)
[36] 周晏锋,严玲,李胜利,等. 690 MPa级海洋工程用钢的高温热塑性[J]. 金属热处理,2016,41(8):14.(ZHOU Yan-feng,YAN Ling,LI Sheng-li,et al. Hot plasticity of 690 MPa grade steel for marine engineering[J]. Heat Treat Metal,2016,41(8):14.)
[37] 陈明昕,杨晓江,孟庆勇. 中锰钢高温热塑性研究[J]. 钢铁研究学报,2020,32(6):519.(CHEN Ming-xin,YANG Xiao-jiang,MENG Qing-yong. Study on high temperature thermoplasticity of medium manganese steel[J]. Journal of Iron and Steel Research,2020,32(6):519.)
[38] 冯运莉,段宝美,胡小明,等. V-N微合金化Q420B大规格角钢连铸坯高温热塑性的研究[J]. 热加工工艺,2014,43(16):57.(FENG Yun-li,DUAN Bao-mei,HU Xiao-ming,et al. Study on high-temperature thermal plasticity of V-N microalloying Q420B large width angle steel continuous cast slab[J]. Hot Working Technology,2014,43(16):57.)
[39] 王昆鹏,王郢,廖家明,等. 超深拉拔类线材夹杂物及断口分析[J]. 钢铁,2022,57(2):101.(WANG Kun-peng,WANG Ying,LIAO Jia-ming,et al. Investigation on inclusions and breakages in ultra-deep drawing wire rod[J]. Iron and Steel,2022,57(2):101.)
[40] Banks K M,Tuling A,Mintz B. Influence of thermal history on hot ductility of steel and its relationship to the problem of cracking in continuous casting[J]. Materials Science and Technology,2012,28(5):536.
[41] Mintz B. Understanding the low temperature end of the hot ductility trough in steels[J]. Materials Science and Technology,2008,24(1):112.
[42] 唐国章,曾亚南,李俊国. 二冷区温度波动下含Nb-Ti微合金钢热塑性行为研究[J]. 热加工工艺,2016,45(22):47.(TANG Guo-zhang,ZENG Ya-nan,LI Jun-guo. Research on hot ductility behavior of Nb-Ti microalloyed steel with temperature fluctuation in secondary cooling zone[J]. Hot Working Technology,2016,45(22):47.)
[43] MA Fan-jun,WEN Guang-hua,WANG Wan-lin. Effect of cooling rates on the second-phase precipitation and proeutectoid phase transformation of a Nb-Ti microalloyed steel slab[J]. Steel Research International,2013,84(4),370.
[44] 邹雷雷,刘青,杜肖臣,等. 基于非调质钢凝固特性的二次冷却控制[J]. 工程科学学报,2022,44(3):357.(ZOU Lei-lei,LIU Qing,DU Xiao-chen,et al. Secondary cooling control based on solidification characteristics of non-quenched and tempered steel[J]. Chinese Journal of Engineering,2022,44(3):357.)