卷取温度对高强贝氏体双相钢组织性能的影响
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摘要
采用UFC-TMCP技术生产了600 MPa级热轧贝氏体双相钢。采用光学显微镜、扫描电镜和拉伸试验等研究了卷取温度对其组织性能的影响。结果表明:当卷取温度由480℃降至400℃时,铁素体平均晶粒尺寸由6.1μm减小到3.8μm,体积分数由75.7%减少到69.2%,组织中贝氏体由粒状向板条状转变,钢的抗拉强度也增加至636 MPa,伸长率较高均在25.0%左右,扩孔率先增加后减小。440℃卷取时钢中铁素体晶粒尺寸为5.2μm,屈服强度为526 MPa,抗拉强度达到628 MPa,伸长率为25.0%,扩孔率高达116%,表现出优良的强塑性匹配和高的延伸凸缘性能。
600 MPa grade hot rolled bainite dual phase steel was prepared by UFC-TMCP technology,and the effects of coiling temperature on microstructure and properties of the steel were investigated by means of optical microscope,scanning electron microscopy and tensile test. The results show that when the coiling temperature decreases from 480 ℃ to 400 ℃,the average grain size of ferrite of the steel decreases from 6. 1 μm to 3. 8 μm,the volume fraction of the ferrite decreases from 75. 7% to 69. 2%,the granular bainite transforms to lath bainite,and the tensile strength of the steel increases up to 636 MPa,the elongation is about 25. 0% and the hole expansion rate increases first and then decreases. When the coiling temperature is 440 ℃,the grain size of ferrite,yield strength,tensile strength,elongation and the hole expansion rate of the steel are 5. 2 μm,526 MPa,628 MPa,25. 0% and 116%,respectively,exhibiting excellent strength,ductility and high stretch-flangeability.
600 MPa grade hot rolled bainite dual phase steel was prepared by UFC-TMCP technology,and the effects of coiling temperature on microstructure and properties of the steel were investigated by means of optical microscope,scanning electron microscopy and tensile test. The results show that when the coiling temperature decreases from 480 ℃ to 400 ℃,the average grain size of ferrite of the steel decreases from 6. 1 μm to 3. 8 μm,the volume fraction of the ferrite decreases from 75. 7% to 69. 2%,the granular bainite transforms to lath bainite,and the tensile strength of the steel increases up to 636 MPa,the elongation is about 25. 0% and the hole expansion rate increases first and then decreases. When the coiling temperature is 440 ℃,the grain size of ferrite,yield strength,tensile strength,elongation and the hole expansion rate of the steel are 5. 2 μm,526 MPa,628 MPa,25. 0% and 116%,respectively,exhibiting excellent strength,ductility and high stretch-flangeability.
引文
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[16]徐莽,蔡晓辉,弓俊杰,等.铁素体贝氏体双相钢延伸凸缘性能及裂纹扩展行为[J].材料热处理学报,2016,37(11):108-112.XU Mang,CAI Xiao-hui,GONG Jun-jie,et al.Stretch-flangeability and crack growth behavior of ferrite/bainite dual phase steel[J].Transactions of Materials and Heat Treatment,2016,37(11):108-112.
[2]Tang C J,Liu S L,Shang C J.Micromechanical behavior and failure mechanism of F/B multi-phase high performance steel[J].Journal of Iron and Steel Research,2016,23(5):489-494.
[3]Varshneya A,Sangala S,Kundub S,et al.Super strong and highly ductile low alloy multiphase steels consisting of bainite,ferrite and retained austenite[J].Materials and Design,2016,95(5):75-88.
[4]吴腾,吴润,熊维亮,等.终轧温度对C-Mn型热轧双相钢组织与性能的影响[J].金属热处理,2017,42(4):124-127.WU Teng,WU Run,XIONG Wei-liang,et al.Effect of finishing rolling temperature on microstructure and mechanical properties of C-Mn hot-rolled dual phase steel[J].Heat Treatment of Metals,2017,42(4):124-127.
[5]康永林.现代汽车板的质量控制与成形性[M].北京:冶金工业出版社,1999.
[6]魏元生.第三代高强度汽车钢的性能与应用[J].金属热处理,2015,40(12):34-39.WEI Yuan-sheng.Performance and application of the 3rd generation high strength automobile steel[J].Heat Treatment of Metals,2015,40(12):34-39.
[7]潘红波,汪杨,阎军,等.钒微合金化600 MPa级高强钢筋的组织与性能[J].材料热处理学报,2016,37(3):114-121.PAN Hong-bo,WANG Yang,YAN Jun,et al.Microstructure and properties of 600 MPa grade vanadium-microalloyed high strength steel rebar[J].Transactions of Materials and Heat Treatment,2013,34(10):55-61.
[8]Lee Y K.Empirical formula of isothermal bainite start temperature of steels[J].Journal of Materials Science Letters,2002,22(16):1253-1255.
[9]Capdevila C,Caballero F G,Garcia D E,et al.Determination of Ms temperature in steels:a Bayesian neural network model[J].ISIJ International,2002,42(8):894-902.
[10]徐平光,方鸿生,白秉哲,等.仿晶界型铁素体/粒状贝氏体复相组织的韧性[J].金属学报,2002,38(3):255-260.XU Ping-guang,FANG Hong-sheng,BAI Bing-zhe,et al.Toughness of grain boundary allotriomorphic ferrite/granular bainite duplex microstructure[J].Acta Metallurgica Sinica,2002,38(3):255-260.
[11]曾尚武,赵征志,赵爱民,等.贝氏体区等温温度对含钒TRIP1180钢组织性能的影响[J].材料热处理学报,2014,35(1):120-124.ZENG Shang-wu,ZHAO Zheng-zhi,ZHAO Ai-min,et al.Effect of isothermal bainite transformation temperature on microstructure and mechanicalproperties of TRIP1180 steel containing vanadium[J].Transactions of Materials and Heat Treatment,2014,35(1):120-124.
[12]Xu P G,Fang H S,Bai P Z,et al.New duplex microstructure of grain boundary allotriomorphic ferrite/granular bainite[J].Journal of Iron and Steel Research International,2002,9(2):33-38.
[13]Lee J,Lee S J,Bruno C,et al.Effect of micro-alloying elements on the stretch-flangeability of dual phase steel[J].Materials Science and Engineering A,2012,536:231-238.
[14]商艳,丁桦,王卫卫,等.含Nb低碳FB钢组织与扩孔性能的研究[J].钢铁,2014,35(1):120-124.SHANG Yan,DING Hua,WANG Wei-wei,et al.Study of microstructure and stretch-flange-formability of low carbon FB steel with niobium[J].Iron and Steel,2008,43(10):74-90.
[15]Hyun D I,oak S M,Kang S S,et al.Estimation of hole flanggeability for high strength steel plates[J].Journal of Materials Processing Technology,2002,130(131):9-13.
[16]徐莽,蔡晓辉,弓俊杰,等.铁素体贝氏体双相钢延伸凸缘性能及裂纹扩展行为[J].材料热处理学报,2016,37(11):108-112.XU Mang,CAI Xiao-hui,GONG Jun-jie,et al.Stretch-flangeability and crack growth behavior of ferrite/bainite dual phase steel[J].Transactions of Materials and Heat Treatment,2016,37(11):108-112.