Abstract：The comprehensive mechanical properties of ultra-high strength complex phase steel were optimized furtherly by regulating the microstructure morphology and the ratio of each phase structure. The enhancement mechanism of strength-plasticity was studied by characterization methods of scanning electron microscopy (SEM), electronic probe micro-analysis (EPMA) and transmission electron microscopy (TEM). The results show that the microstructure is composed of about 37% ferrite, 49% bainite and 14% retained austenite (volume fraction) when the annealing temperature is 820 ℃ which is in the (γ+α) two-phase critical region. The ferrite structure is composed of recrystallized ferrite and proeutectoid ferrite, bainite is blocky. Retained austenite is irregularly granular and mainly distributed at the ferrite grain boundary or between the ferrite and bainite phase interface, and its grain size is basically proportional to the BCC structure of the "carbon-poor region" around it. When the annealing temperature is 910 ℃ which is in the single-phase austenite region, the microstructure is composed of about 19% proeutectoid ferrite, 61% lath-like bainite ferrite and 20% lamellar retained austenite with a thickness of 60-130 nm. The bainite ferrite is a massive reference unit with recrystallized austenite grains as the phase transition and distributes in different directions. The proportion of high angle grain boundaries reaches 85.4%. The second phase particles of V(C,N) in the matrix are interphase precipitated, the diameter of the precipitated particles is 3-9 nm, the average column spacing is about 31 nm, and the calculated contribution to the strength of the material is about 281 MPa. The comprehensive mechanical properties of ultra-high strength complex phase steel are closely related to its micro-morphology, crystal structure and crystal orientation, second-phase precipitated particles, high-density dislocations and the TRIP effect contribution of retained austenite. When the annealing temperature is in the single-phase austenite region, the tensile strength of the complex phase steel reaches 1 226 MPa, while the elongation and hole expansion rate increase to 19.1% and 51%, respectively, and the product of strength and plasticity reaches 23.42 GPa·%. The research results can provide a reference for improving the comprehensive performance of high-strength materials.
CHU X H, GAO P F, CHEN W J,et al. Effect of Cr and isothermal holding temperature on microstructure and properties of complex phase steel with high formability(CH steel)[J]. Journal of Iron and Steel Research International, 2023, 30(2): 328.
[2]
陈炜煊,张永强,邱木生,等. CP1180镀锌复相钢电阻点焊焊接特性研究[J]. 焊接技术,2023,52(5):51. (CHEN W X, ZHANG Y Q, QIU M S, et al. Study on welding characteristics of CP1180 galvanized complex-phase steel by resistance spot welding[J]. Welding Technology, 2023, 52(5): 51.)
[3]
田秀刚,刘靖宝,邝霜. Cr-Mo-Nb-Ti-B系1 180 MPa级复相钢的性能稳定性[J]. 金属热处理,2022,47(9):182. (TIAN X G, LIU J B, KUANG S. Performance stability of 1 180 MPa complex phase steel in Cr-Mo-Nb-Ti-B series[J]. Heat Treatment of Metals, 2022, 47(9): 182.)
[4]
邹航,徐光,刘曼. 轧后冷却工艺对低碳高强复相钢组织和性能的影响[J]. 钢铁研究学报,2020,32(8):746. (ZOU H, XU G, LIU M. Effect of cooling process after rolling on microstructure and properties of a low-carbon high-strength complex-phase steel[J]. Journal of Iron and Steel Research, 2020, 32(8): 746.)
[5]
许立雄. Fe-Mn-Al系轻质低温钢的组织调控及强韧化机理研究[D]. 北京:北京科技大学,2019. (XU L X. Study on Microstructure Control and Strengthening-Toughening Mechanism of Fe-Mn-Al Light-Weight Cryogenic Steel[D]. Beijing:University of Science and Technology Beijing, 2019.)
[6]
周乃鹏. 基于TRIP效应的Fe-Mn-Al-C钢组织性能调控及变形机制研究[D]. 北京:北京科技大学,2020. (ZHOU N P. Investigation on Microstructure-Properties Control and Deformation Mechanism of Fe-Mn-Al-C TRIP Steels[D]. Beijing:University of Science and Technology Beijing, 2021.)
[7]
CHOI J Y,JI J H,SI W H,et al. Effects of nitrogen content on TRIP of Fe-20Cr-5Mn-xN duplex stainless steel[J]. Materials Science and Engineering A,2012,534:673.
[8]
ZHAO B,ZHAO T,LI G,et al. Effect of Nitrogen on Transformation Behaviors and Microstructure of VN Microalloyed steel[M]. Cham: Springer International Publishing,2016.
[9]
史根豪. 增氮与等温转变对低碳 Mo-V-Ti 钢复相组织和力学性能的影响研究[D]. 秦皇岛:燕山大学,2021. (SHI G H. Effects of Nitrogen Addition and Isothermal Transformation on Multi-phase Microstructure and Mechanical Properties of Low Carbon Mo-V-Ti Steel[D]. Qinhuangdao:Yanshan University,2021.)
[10]
侯晓英,毕永杰,郝亮. 热轧TRIP980钢微观组织及强化机制分析[J]. 钢铁,2019,54(4):63. (HOU X Y, BI Y J, HAO L. Analysis on microstructure and strengthening mechanisms of hot-rolled TRIP980 steel[J]. Iron and Steel, 2019, 54(4): 63.)
[11]
余灿生, 郑之旺, 常智渊,等. 热镀锌工艺对1 180 MPa级双相钢组织性能的影响[J]. 中国冶金,2023,33(6):108. (YU C S, ZHENG Z W, CHANG Z Y, et al. Effect of hot-dip galvanizing process on microstructure and properties of 1 180 MPa grade dual-phase steel[J]. China Metallurgy, 2023, 33(6): 108.)
[12]
侯晓英,王军,丁明凯,等. 基体组织对800 MPa级双相钢强塑性机制的影响[J]. 金属热处理,2022,47(12):222. (HOU X Y,WANG J,DING M K, et al. Effect of matrix structure on mechanism of strength and ductility for 800 MPa grade dual phase steel[J]. Heat Treatment of Metals, 2022, 47(12): 222.)
[13]
侯晓英,孙卫华,曹光明,等. 一种TRIP型双相钢的形貌特征与强塑性机制[J]. 材料热处理学报,2021,42(5):104. (HOU X Y,SUN W H,CAO G M,Morphological characteristics and the mechanism of strength-ductility of a TRIP-assisted dual-phase steel[J]. Transactions of Materials and Heat Treatment, 2021, 42(5): 104.)
[14]
TANG C J, SHANG C J, LIU S L, et al. Effect of volume fraction of bainite on strain hardening behavior and deformation mechanism of F/B multi-phase steel[J]. Material Science and Engineering A, 2018, 731: 173.
[15]
邹英,刘华赛,韩赟,等. 热基镀锌高扩孔钢的组织性能研究及其工业试制[J]. 轧钢,2022,39(4):76. (ZOU Y, LIU H S, HAN Y, et al. Study on microstructure and properties of hot-rolled galvanized high hole expansion steel and its industrial trial production[J]. Steel Rolling, 2022, 39(4): 76.)
[16]
薛建忠. 800 MPa级热轧复相钢的组织控制及扩孔性能研究[D]. 北京:北京科技大学,2021.(XUE J Z. Study on Microstructure Control and Hole Expansion Performance of 800 MPa Grade Hot-Rolled Complex Phase Steels[D]. Beijing:University of Science and Technology Beijing, 2021.)
[17]
王超. 高强度TRIP钢组织性能表征及基于微观组织的有限元模拟[D]. 沈阳:东北大学,2014. (WANG C. Characterization of Microstructures and Mechanical Properties in High Strength TRIP Steels and Microstructure-based Finite Element Simulation[D]. Shenyang:Northeastern University,2014.)
[18]
赵显蒙,康永林,韩启航. 1 000 MPa级冷轧双相钢奥氏体的等温相变动力学[J]. 材料热处理学报,2013,34(1):53.(ZHAO X M, KANG Y L, HAN Q H. Austenite isothermal transformation kinetics of a 1 000 MPa grade cold rolled dual phase steel[J]. Transactions of Materials and Heat Treatment, 2013,34(1):53.)
[19]
吴腾. 低碳热轧多相钢中形变亚结构的形成及作用[D]. 武汉:武汉科技大学,2021.(WU T. Formation and Effect of Deformation Substructure in Low Carbon Hot-Rolled Multiphase-Steel[D]. Wuhan:Wuhan University of Science and Technology,2021.)
[20]
SUIKKANCE P P, CAYRON C, DCARDO A J, et al. Crystallographic analysis of isothermally transformed bainite in 0.2C-2.0Mn-1.5Si-0.6Cr steel using EBSD[J]. Journal of Materials Science and Technology, 2011, 29(10): 359.
[21]
SUIKKANCE P P, CAYRON C, DCARDO A J, et al. Crystallographic analysis of martensite in 0.2C-2.0Mn-1.5Si-0.6Cr steel using EBSD[J]. Journal of Materials Science and Technology, 2011, 27(3): 920.
[22]
KANESHITA T, MIYAMOTO G, FURUHARA T. Variant selection in grain boundary nucleation of bainite in Fe-2Mn-C alloys[J]. Acta Materialia, 2017, 127: 368.
[23]
BRITO R M, KESTENBACH H J. On the dispersion hardening potential of interphase precipitation in micro-alloyed niobium steel[J]. Journal of Materials Science, 1981, 16:1257.
[24]
YI H L, YANG X U, SUN M X, et al. Influence of finishing cooling temperature and holding time on nanometer-size carbide of Nb-Ti microalloyed steel[J]. Journal of Iron and Steel Research International, 2014, 21(4): 433.
[25]
杨洪波,王豪,赵旭,等. 微合金高强钢纳米相间析出行为研究进展[J]. 钢铁,2021,56(12):10. (YANG H B, WANG H, ZHAO X, et al. Research progress on nano-scale interphase precipitation behavior of microalloyed high-strength steel[J]. Iron and Steel, 2021, 56(12): 10.)
[26]
周清. 塑性变形微观组织及控制[M]. 北京:科学出版社,2016. (ZHOU Q. Microstructure and Control of Plastic Deformation [M]. Beijing: Science Press, 2016.)
[27]
张伟,潘跃,刘华赛,等. 应变速率对增强成形性双相钢性能影响分析[J]. 钢铁,2022,57(4):123. (ZHANG W, PAN Y, LIU H S, et al. Effect of strain rate on properties of dual phase steel with high formability[J]. Iron and Steel, 2022, 57(4): 123.)
[28]
凌雨,胡锋,严恒,等. 2 GPa中碳中锰纳米贝氏体钢的相变和塑性机理[J]. 钢铁,2022,57(11):131. (LING Y, HU F, YAN H, et al. Microstructural transformation and plasticity mechanism of 2 GPa medium-carbon medium-manganese nano-bainitic steel[J]. Iron and Steel, 2022, 57(11): 131.)
[29]
蒋爱娟,祝贞凤,高千林,等. 淬火制度对Q&P钢微观组织和力学性能的影响[J]. 钢铁,2019,54(10):80. (JIANG A J, ZHU Z F, GAO Q L, et al. Influence of quenching process on microstructure and mechanical properties of Q&P stee[J]. Iron and Steel, 2019, 54(10):80.)
[30]
闫述. 基于亚稳奥氏体控制的先进高强钢组织性能研究[D]. 沈阳:东北大学,2016. (YAN S. Microstructure and Properties of Advanced High Strength Steels based on Control of Meta-stable Austenite[D]. Shenyang:Northeastern University,2016.)
2024, Vol. 34 
