Design and application of new mold flux for high-Al steel continuous casting
LIU Chengjun1,2, QI Jie1,2, JIANG Maofa1,2
1. Key Laboratory of Ecological Metallurgy of Multimetallic Mineral Ministry Education, Shenyang 110819, Liaoning, China; 2. School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China
Abstract:In the industrial application process of low reactive CaO-Al2O3 based mold flux, the slag rim grow fast, and the sticking alarm was frequent, so the stable continuous casting production cannot be realized. In view of the above problems, a new CaO-Al2O3-based mold flux was designed and applied in industry on the basis of analyzing the problems of industrial mold flux. The results show that the main reasons for the deterioration of the performance of the mold flux were the strong crystallization performance of the industrial mold flux and the premature precipitation of Ca12Al14O32F2 and LiAlO2. The phase diagram analysis show that adjusting the w(CaO)/w(Al2O3) value is one of the effective measures to control the crystallization performance. With the increase of w(CaO)/w(Al2O3) from 0.93 to 1.65, the melting temperature decreased from 1 050 ℃ to 959 ℃. Under the influence of melt structure depolymerization, the viscosity decreased from 0.132 Pa·s to 0.054 Pa·s at 1 300 ℃. With the increase of w(CaO)/w(Al2O3), the crystallization properties of mold flux were first inhibited and then gradually enhanced, the breaking temperature decreased first and then increased. Near the breaking temperature, the change rule of the crystallization phase was LiAlO2→Ca2Al2SiO7→Ca12Al14O32F2+LiAlO2. The change rule of crystalline phase after full crystallization is LiAlO2+Ca2Al2SiO7→Ca2Al2SiO7→LiAlO2+Ca12Al14O32F2+Ca3B2O6. Based on the above results, a new type of mold flux was designed. The melting temperature, viscosity and breaking temperature of the new mold flux are lower than those of the previous industrial test slag. Moreover, the new g mold flux can maintain a single liquid phase above 1 000 ℃, and the crystallization performance is obviously weakened. The continuous casting of high aluminum low density and high strength steel was successfully realized by using the new mold flux, and the new mold flux has good stability in the casting process. The quality of continuous casting slab is significantly improved.An important support can be provided for the series development of low density and high strength steel and the design and the development of low reactivity mold fluxes for high aluminum steel continuous casting.
刘承军, 亓捷, 姜茂发. 高铝钢用新型连铸保护渣的设计开发与应用[J]. 钢铁, 2023, 58(9): 116-126.
LIU Chengjun, QI Jie, JIANG Maofa. Design and application of new mold flux for high-Al steel continuous casting[J]. Iron and Steel, 2023, 58(9): 116-126.
[1] JACQUES P, FURNEMONT Q, PARDOEN T. On the role of martensitic transformation on damage and cracking resistance in TRIP-assisted multiphase steels[J]. Acta Materialia, 2001, 49(1): 139. [2] 江利, 陈涛. 相变诱发塑性锚杆材料控冷热处理组织与性能[J]. 中国矿业大学学报, 1999, 28(3): 269. (JIANG L,CHEN T. Microstructure and property of the controlled cooling heat-treatment of TRIP-bolt steel[J]. Journal of China University of Mining and Technology,1999,28(3):269.) [3] 谢晓心, 张新仁. 主要成分和工艺对极低铁损高磁感无取向电工钢磁性的影响[J]. 钢铁研究, 2003, 31(5): 52. (XIE X X,ZHANG X R. Effect of composition and technology of non-oriented electric steel with ultra-low coreloss and high magnetic induction on its magnetic properties[J]. Research on Iron and Steel,2003,31(5):52.) [4] TONG W P, HAN Z, WANG L M. Low-temperature nitriding of 38CrMoAl steel with a nanostructured surface layer induced by surface mechanical attrition treatment[J].Surface and Coatings Technology, 2008, 202(20): 4957. [5] GAN M, PU W, SHEN L, LI P, et al. Mechanical properties of nitrogen implanted 38CrMoAl nitrided steel[J]. Surface and Coatings Technology, 1994, 66(1/2/3): 288. [6] 刘洋. 无磁钢热变形行为及组织性能研究[D]. 沈阳: 东北大学, 2009. (LIU Y. Study on Hot Deformation Behavior and Microstructures-Properties of Non-Magnetic Steel[D].Shenyang:Northeastern University,2009.) [7] 张彦生, 苏丽娟. 30Mn20Al3无磁钢及低温钢的研究[J]. 金属学报, 1983, 19(4): 1. (ZHANG Y S,SU L J. A study on non-magnetic and cryogenic steel 30Mn20Al3[J]. Acta Metallurgica Sinica,1983,19(4):1.) [8] 何杨. 高铝FeCrAl不锈钢凝固特性及高温力学性能基础研究[D]. 北京: 北京科技大学, 2019. (HE Y. Fundamental Research on the Solidification Characteristics and High-Temperature Mechanical Properties of High-Al FeCrAl Stainless Steel[D]. Beijing:University of Science and Technology Beijing,2019.) [9] SOHN S S, SONG H, KIM J G, et al. Effects of annealing treatment prior to cold rolling on delayed fracture properties in ferrite-austenite duplex lightweight steels[J]. Metallurgical and Materials Transactions A, 2016, 47A(2): 706. [10] 满廷慧, 彭伟, 王子波, 等. Fe-Mn-Al-C低密度钢研究现状及展望[J]. 中国冶金, 2022, 32(1): 11. (MAN T H,PENG W,WANG Z B,et al. Research progress and prospect of Fe-Mn-Al-C low-density steels[J]. China Metallurgy,2022,32(1):11.) [11] RAABE D, SPRINGER H, GUTIERREZ-URRUTIA I, et al. Alloy design, combinatorial synthesis, and microstructure-property relations for low-density Fe-Mn-Al-C austenitic steels[J]. JOM, 2014, 66(9): 1845. [12] YOO J D, PARK K T. Microband-induced plasticity in a high Mn-Al-C light steel[J]. Materials Science and Engineering: A, 2008, 469(1/2): 417. [13] 王强, 仇圣桃, 赵沛, 等. 高铝钢连铸保护渣的研究现状[J]. 炼钢, 2012, 28(1): 74. (WANG Q,QIU S T,ZHAO P,et al. Status of research on mold flux for high aluminum steel[J]. Steelmaking,2012,28(1):74.) [14] 黎江玲. 高铝钢连铸保护渣的物理化学研究[D]. 北京: 北京科技大学, 2016. (LI J L. Study on the Physics and Chemistry of Mold Flux for High Aluminum Steel Casting[D]. Beijing:University of Science and Technology Beijing,2016.) [15] 何生平, 王谦, 曾建华, 等. 高铝钢连铸保护渣性能的控制[J]. 钢铁研究学报, 2009, 21(12): 59. (HE S P,WANG Q,ZENG J H,et al. Effect of Li2O on crystallization properties of CaO-Al2O3 based mold fluxes[J]. Journal of Iron and Steel Research,2009,21(12):59.) [16] 张江浩, 亓捷, 刘承军, 等. Li2O对CaO-Al2O3基保护渣结晶性能的影响[J].钢铁研究学报, 2022, 34(11): 1211. (ZHANG J H,QI J,LIU C J,et al. Effect of Li2O on crystallization properties of CaO-Al2O3 based mold fluxes[J]. Journal of Iron and Steel Research,2022,34(11):1211.) [17] 王旭凤, 王强强,张旭彬, 等. AlN对高铝钢用CaO-SiO2基保护渣性能的影响[J].钢铁, 2022, 57(5): 64. (WANG X F,WANG Q Q,ZHANG X B,et al. Effect of AlN on properties of CaO-SiO2 based mold fluxes for high-Al steel[J]. Iron and Steel,2022,57(5):64.) [18] 莫嵘臻, 张立峰, 任英, 等.高铝钢用低反应型保护渣成分对其黏度的影响[J]. 钢铁研究学报, 2021, 33(8): 695. (MO R Z,ZHANG L F,REN Y,et al. Review on effect of composition on viscosity of low-reactive mold flux for high-Al steel[J]. Journal of Iron and Steel Research,2021,33(8):695.) [19] JI C X, CUI Y, ZENG Z, et al. Continuous casting of high-Al steel in Shougang Jingtang steel works[J]. Journal of Iron and Steel Research International, 2015, 22(s1): 53. [20] YU X, WEN G H, TANG P, et al. Behavior of mold slag used for 20Mn23Al nonmagnetic steel during casting[J]. Journal of Iron and Steel Research International, 2011, 18(1): 20. [21] BECKER J J, MADDEN M A, NATARAJAN T T, et al. Liquid/solid Interactions during continuous casting of high-Al advanced high strength steels[C]//Aistech-Iron and Steel Technology Conference Proceedings. Charlotte:Association for Iron and Steel Technology,2005: 99. [22] MOON K H, PARK M S, YOO S, et al. Molten mold flux technology for continuous casting of the ULC and TWIP steel[C]//Proceedings of the 8th Pacific Rim International Congress on Advanced Materials and Processing. Switzerland:Springer International Publishing, 2016: 735. [23] 高铝钢及微合金钢板坯连铸关键技术开发与应用[J]. 中国冶金, 2023, 33(2): 144. (Development and application of key technologies for slab continuous casting of high aluminum steel and microalloyed steel[J]. China Metallurgy,2023,33(2):144.) [24] OMOTO T, SUZUKI T, OGATA H. Development of "SIPS series" mold powder for high Al electromagnetic steel[J]. Shinagawa Technical Report, 2007, 50: 57. [25] SHAO H Q, GAO E, WANG W, et al. Effect of fluorine and CaO/Al2O3 mass ratio on the viscosity and structure of CaO-Al2O3-based mold fluxes[J]. Journal of the American Ceramic Society, 2019, 102(8): 1. [26] STREET S, JAMES K, MINOR N, et al. Production of high-aluminum steel slabs[J]. Iron and Steel Technology, 2008, 5(7): 38. [27] BLAZEK K, YIN H, SKOCZYLAS G, et al. Development and evaluation of lime-alumina-based mold powders for casting high-aluminum TRIP steel grades[J]. Iron and Steel Technology, 2011, 8(3): 232. [28] 余杰, 王万林, 肖丹, 等. MgO和BaO对CaO-Al2O3系保护渣熔化与结晶行为的影响[J]. 连铸, 2018 (4): 37. (YU J,WANG W L,XIAO D,et al. Effects of MgO and BaO on the melting and crystallization behaviors of the mold flux in CaO-Al2O3 series[J]. Continuous Casting,2018(4):37.) [29] 冯鑫, 姚稳, 黎江玲. BaO对CaO-Al2O3基保护渣熔化温度、结晶及微观结构的影响[J]. 连铸, 2021 (2): 38. (FENG X,YAO W,LI J L. Effect of BaO on melting temperature, crystallization and structure of CaO-Al2O3 based mold flux[J]. Continuous Casting,2021(2):38.) [30] 靳贺斌, 吉俊德, 王时松, 等. 钢渣反应对高钛钢保护渣物化特性的影响[J].连铸, 2021 (6): 59. (JIN H B,JI J D,WANG S S,et al. Effect of steel-slag reaction on physicochemical properties of mold fluxes of high-titanium steel[J]. Continuous Casting,2021(6):59.) [31] 李建民, 姜茂发, 孙丽枫. 20Mn23AlV钢用低反应性连铸保护渣的开发[J].中国冶金, 2017, 27(12): 28. (LI J M,JIANG M F,SUN L F. Development of low responsiveness mold fluxes for 20Mn23AlV[J]. China Metallurgy,2017,27(12):28.) [32] 朱立光, 张晓仕, 王杏娟, 等. 高钛焊丝钢CaO-Al2O3基专用保护渣熔化特性分析[J].中国冶金, 2020, 30(10): 9. (ZHU L G,ZHANG X S,WANG X J, et al. Development of low responsiveness mold fluxes for 20Mn23AlV[J]. China Metallurgy,2020,30(10):9.) [33] CHO J W, BLAZEK K, FRAZEE M, et al. Assessment of CaO-Al2O3 based mold flux system for high aluminum TRIP casting[J]. ISIJ International, 2013, 53(1): 62. [34] LIU Q, WEN G, LI J, et al. Development of mould fluxes based on lime-alumina slag system for casting high aluminium TRIP steel[J]. Ironmaking and Steelmaking, 2014, 41(4):292. [35] KIM T S, PARK J H. Structure-viscosity relationship of low-silica calcium aluminosilicate melts[J]. ISIJ International, 2014, 54(9): 2031. [36] YAN W, CHEN W, YANG Y, et al. Effect of CaO/Al2O3 ratio on viscosity and crystallisation behaviour of mould flux for high Al non-magnetic steel[J]. Ironmaking and Steelmaking, 2015, 42(9): 698.