Effects of Mg and La on the evolution of inclusions and microstructure in Ca-Ti treated steel

Abstract

The evolution of inclusions and the formation of acicular ferrite (AF) in Ca-Ti treated steel was systematically investigated after Mg and La addition. The inclusions in the molten steel were Ca-Al-O, Ca-Al-Mg-O, and La-Mg-Ca-Al-O after Ca, Mg, and La addition, respectively. The type of oxide inclusion in the final quenched samples was the same as that in the molten steel. However, unlike those in molten steel, the inclusions were Ca-Al-Ti-O + MnS, Ca-Mg-Al-Ti-O + MnS, and La-Ca-Mg-Al-Ti-O + MnS in Mg-free, Mg-containing, and La-containing samples, respectively. The inclusions distributed dispersedly in the La-containing sample. In addition, the average size of the inclusions in the La-containing sample was the smallest, while the number density of inclusions was the highest. The size of effective inclusions (nucleus of AF formation) was mainly in the range of 1–3 µm. In addition, the content of ferrite side plates (FSP) decreased, while the percentage of AF increased by 16.2% due to the increase in the number of effective inclusions in the La-containing sample in this study.

Keywords

lanthanum / magnesium / calcium / titanium / nonmetallic inclusions / evolution / acicular ferrite

References

[1] Wan XL, Wei R, Wu KM. Effect of acicular ferrite formation on grain refinement in the coarse-grained region of heat-affected zone. Mater. Charact., 2010, 61(7): 726.

[2] Medina SF, Gómez M, Rancel L. Grain refinement by intragranular nucleation of ferrite in a high nitrogen content vanadium microalloyed steel. Scr. Mater., 2008, 58(12): 1110.

[3] H. Bhadeshia and R. Honeycombe, Steels Microstructure and Properties, 4th ed., Butterworth-Heinemann, Elsevier Ltd., 2017: 401–419.

[4] X. Wang, C. Wang, J. Kang, G. Yuan, R.D.K. Misra, and G.D. Wang, Improved toughness of double-pass welding heat affected zone by fine Ti-Ca oxide inclusions for high-strength low-alloy steel, Mater. Sci. Eng. A, 780(2020), art. No. 139198.

[5] Loder D, Michelic SK, Mayerhofer A, Bernhard C. On the capability of nonmetallic inclusions to act as nuclei for acicular ferrite in different steel grades. Metall. Mater. Trans. B, 2017, 48(4): 1992.

[6] Byun JS, Shim JH, Cho YW, Lee DN. Non-metallic inclusion and intragranular nucleation of ferrite in Ti-killed C-Mn steel. Acta Mater., 2003, 51(6): 1593.

[7] Jin HH, Shim JH, Cho YW, Lee HC. Formation of intragranular acicular ferrite grains in a Ti-containing low carbon steel. ISIJ Int., 2003, 43(7): 1111.

[8] Wen B, Song B, Pan N, Hu QY, Mao JH. Effect of SiMg alloy on inclusions and microstructures of 16Mn steel. Ironmaking Steelmaking, 2011, 38(8): 577.

[9] Mu WZ, Jönsson PG, Nakajima K. Recent aspects on the effect of inclusion characteristics on the intragranular ferrite formation in low alloy steels: A review. High Temp. Mater. Processes, 2017, 36(4): 309.

[10] Sarma DS, Karasev AV, Jönsson PG. On the role of non-metallic inclusions in the nucleation of acicular ferrite in steels. ISIJ Int., 2009, 49(7): 1063.

[11] Furuhara T, Yamaguchi J, Sugita N, Miyamoto G, Maki T. Nucleation of proeutectoid ferrite on complex precipitates in austenite. ISIJ Int., 2003, 43(10): 1630.

[12] Shim JH, Oh YJ, Suh JY, Cho YW, Shim JD, Byun JS, Lee DN. Ferrite nucleation potency of non-metallic inclusions in medium carbon steels. Acta Mater., 2001, 49(12): 2115.

[13] Li XB, Min Y, Yu Z, Liu CJ, Jiang MF. Effect of Mg addition on nucleation of intra-granular acicular ferrite in Al-killed low carbon steel. J. Iron Steel Res. Int., 2016, 23(5): 415.

[14] Koseki T, Thewlis G. Overview Inclusion assisted micro-structure control in C-Mn and low alloy steel welds. Mater. Sci. Technol., 2005, 21(8): 867.

[15] Xu LY, Yang J, Wang RZ, Wang WL, Wang YN. Effect of Mg addition on formation of intragranular acicular ferrite in heat-affected zone of steel plate after high-heat-input welding. J. Iron Steel Res. Int., 2018, 25(4): 433.

[16] Jiang M, Wang XH, Chen B, Wang WJ. Laboratory study on evolution mechanisms of non-metallic inclusions in high strength alloyed steel refined by high basicity slag. ISIJ Int., 2010, 50(1): 95.

[17] Park JH, Lee SB, Kim DS. Inclusion control of ferritic stainless steel by aluminum deoxidation and calcium treatment. Metall. Mater. Trans. B, 2005, 36(1): 67.

[18] Park JH, Lee SB, Gaye HR. Thermodynamics of the formation of MgO-Al₂O₃-TiO_x inclusions in Ti-stabilized 11Cr ferritic stainless steel. Metall. Mater. Trans. B, 2008, 39(6): 853.

[19] Opiela M, Grajcar A. Modification of non-metallic inclusions by rare-earth elements in microalloyed steels. Arch. Foundry Eng., 2012, 12(2): 129.

[20] Deng XX, Jiang M, Wang XH. Mechanisms of inclusion evolution and intra-granular acicular ferrite formation in steels containing rare earth elements. Acta Metall. Sinica Engl. Lett., 2012, 25(3): 241

[21] Song MM, Song B, Zhang SH, Xue ZL, Yang ZB, Xu RS. Role of lanthanum addition on acicular ferrite transformation in C-Mn steel. ISIJ Int., 2017, 57(7): 1261.

[22] Zhao XD, Jiang J, Li GB, Li FZ. Kinetics of formation of large-dimension rare earth inclusion in steels. J. Rare Earths, 2004, 22(3): 403

[23] X.K. Cui, B. Song, Z.B. Yang, Z. Liu, L.F. Li, and L. Wang, Effect of Mg on the evolution of inclusions and formation of acicular ferrite in La-Ti-treated steels, Steel Res. Int., 91(2020), No. 4, art. No. 1900563.

[24] Kim HS, Chang CH, Lee HG. Evolution of inclusions and resultant microstructural change with Mg addition in Mn/Si/Ti deoxidized steels. Scripta Mater., 2005, 53(11): 1253.

[25] H.N. Lou, C. Wang, B.X. Wang, Z.D. Wang, Y.Q. Li, and Z.G. Chen, Inclusion evolution behavior of Ti-Mg oxide metallurgy steel and its effect on a high heat input welding HAZ, Metals, 8(2018), No. 7, art. No. 534.

[26] Zhang LF, Thomas BG. State of the art in evaluation and control of steel cleanliness. ISIJ Int., 2003, 43(3): 271.

[27] Wang XH, Li XG, Li Q, Huang FX, Li HB, Yang J. Control of stringer shaped non-metallic inclusions of CaO-Al₂O₃ system in API X80 linepipe steel plates. Steel Res. Int., 2014, 85(2): 155.

[28] Li JY, Cheng GG, Ruan Q, Pan JX, Chen XR. Formation and evolution of oxide inclusions in titanium-stabilized 18Cr stainless steel. ISIJ Int., 2018, 58(12): 2280.

[29] Pan C, Hu XJ, Zheng JC, Lin P, Chou KC. Effect of calcium content on inclusions during the ladle furnace refining process of AISI 321 stainless steel. Int. J. Miner. Metall. Mater., 2020, 27(11): 1499.

[30] Yang SF, Li JS, Wang ZF, Li J, Lin L. Modification of MgOAl₂O₃ spinel inclusions in Al-killed steel by Ca-treatment. Int. J. Miner. Metall. Mater., 2011, 18(1): 18.

[31] Lou HN, Wang C, Wang BX, Wang ZD, Misra RDK. Effect of Ti-Mg-Ca treatment on properties of heat-affected zone after high heat input welding. J. Iron Steel Res. Int., 2019, 26(5): 501.

[32] Wu ZH, Zheng W, Li GQ, Matsuura H, Tsukihashi F. Effect of inclusions’ behavior on the microstructure in Al-Ti deoxidized and magnesium-treated steel with different aluminum contents. Metall. Mater. Trans. B, 2015, 46(3): 1226.

[33] Y.T. Zhou, S.F. Yang, J.S. Li, W. Liu, and A.P. Dong, Effects of heat-treatment temperature on the microstructure and mechanical properties of steel by MgO nanoparticle additions, Materials, 11(2018), No. 9, art. No. 1707.

[34] C. Wang, X. Wang, J. Kang, G. Yuan, and G.D. Wang, Effect of thermomechanical treatment on acicular ferrite formation in Ti-Ca deoxidized low carbon steel, Metals, 9(2019), No. 3, art. No. 296.

[35] Z. Liu, B. Song, Z.B. Yang, X.K. Cui, L.F. Li, L. Wang, and Z.R. Song, Effect of cerium content on the evolution of inclusions and formation of acicular ferrite in Ti-Mg-killed EH36 steel, Metals, 10(2020), No. 7, art. No. 863.

[36] Bai XF, Sun YH, Chen RM, Zhang YM, Cai YF. Formation and thermodynamics of CaS-bearing inclusions during Ca treatment in oil casting steels. Int. J. Miner. Metall. Mater., 2019, 26(5): 573.

[37] Li Y, Chen CY, Qin GQ, Jiang ZH, Sun M, Chen K. Influence of crucible material on inclusions in 95Cr saw-wire steel deoxidized by Si-Mn. Int. J. Miner. Metall. Mater., 2020, 27(8): 1083.

[38] L.Y. Lan and G.Q. Shao, Morphological evolution of HAZ microstructures in low carbon steel during simulated welding thermal cycle, Micron, 131(2020), art. No. 102828.

[39] Thewlis G. The nature of acicular ferrite in ferrous weld metals and the challenges for microstructure modelling. Mater. Sci. Forum, 2003, 426–432, 4019.

[40] Thewlis G. Classification and quantification of microstructures in steels. Mater. Sci. Technol., 2004, 20(2): 143.

[41] Ye GZ, Jönsson P, Lund T. Thermodynamics and kinetics of the modification of Al₂O₃ inclusions. ISIJ Int., 1996, 36, S105. No. Suppl

[42] Takata R, Yang J, Kuwabara M. Characteristics of inclusions generated during Al-Mg complex deoxidation of molten steel. ISIJ Int., 2007, 47(10): 1379.

[43] Y.Y. Xiao, G.C. Wang, H. Lei, and S. Sridhar, Formation pathways for MgOAl₂O₃ inclusions in iron melt, J. Alloys Compd., 813(2020), art. No. 152243.

[44] Zhang TS, Min Y, Liu CJ, Jiang MF. Effect of Mg addition on the evolution of inclusions in Al-Ca deoxidized melts. ISIJ Int., 2015, 55(8): 1541.

[45] Liu HH, Fu PX, Liu HW, Gao YF, Sun C, Du NY, Li DZ. Effects of rare earth elements on microstructure evolution and mechanical properties of 718H pre-hardened mold steel. J. Mater. Sci. Technol., 2020, 50, 245.

[46] Deng ZY, Chen L, Song GD, Zhu MY. Formation and evolution of non-metallic inclusions in Ti-bearing Al-killed steel during secondary refining process. Metall. Mater. Trans. B, 2020, 51(1): 173.

[47] Zhang TS, Liu CJ, Jiang MF. Effect of Mg on behavior and particle size of inclusions in Al-Ti deoxidized molten steels. Metall. Mater. Trans. B, 2016, 47(4): 2253.

[48] Ren Y, Zhang LF, Yang W, Duan HJ. Formation and thermodynamics of Mg-Al-Ti-O complex inclusions in Mg-Al-Ti-deoxidized steel. Metall. Mater. Trans. B, 2014, 45(6): 2057.

[49] Mu WZ, Dogan N, Coley KS. Agglomeration of non-metallic inclusions at the steel/Ar interface: Model application. Metall. Mater. Trans. B, 2017, 48(4): 2092.

[50] Yu Z, Liu CJ. Evolution mechanism of inclusions in medium-manganese steel by Mg treatment with different aluminum contents. Metall. Mater. Trans. B, 2019, 50(2): 772.

[51] Kimura S, Nakajima K, Mizoguchi S. Behavior of alumina-magnesia complex inclusions and magnesia inclusions on the surface of molten low-carbon steels. Metall. Mater. Trans. B, 2001, 32(1): 79.

[52] Kimura S, Nabeshima Y, Nakajima K, Mizoguchi S. Behavior of nonmetallic inclusions in front of the solid-liquid interface in low-carbon steels. Metall. Mater. Trans. B, 2000, 31(5): 1013.

[53] Li P, Li GQ, Zheng W. Effects of Al-Ti deoxidation on MnS precipitation and the microstructure of non-quenched and tempered steel. J. Iron Steel Res., 2013, 25(11): 49

[54] Mabuchi H, Uemori R, Fujioka M. The role of Mn depletion in intra-granular ferrite transformation in the heat affected zone of welded joints with large heat input in structural steels. ISIJ Int., 1996, 36(11): 1406.

[55] Cheng L, Xu C, Lu LL, Yu L, Wu KM. Experimental and first principle calculation study on titanium, zirconium and aluminum oxides in promoting ferrite nucleation. J. Alloys Compd., 2018, 742, 112.

[56] Li XB, Min Y, Liu CJ, Jiang MF. Effect of Mg addition on the characterization of γ-α phase transformation during continuous cooling in low carbon steel. Steel Res. Int., 2015, 86(12): 1530.

[57] Cheng L, Wu KM. New insights into intragranular ferrite in a low-carbon low-alloy steel. Acta Mater., 2009, 57(13): 3754.