450～780MPa系列双相钢扩孔性能实验
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摘要
目的避免双相钢在成形过程中经常出现的翻边或扩孔开裂的问题,提高生产效率。方法以几种强度级别为450~780 MPa的双相钢为实验对象,测试材料的单向拉伸和扩孔性能,并从微观组织上分析影响双相钢强度和扩孔性能的因素。结果 450~780 MPa强度级别双相钢的屈服强度随铁素体晶粒尺寸的减小而增加,抗拉强度随马氏体体积分数的增加呈近似线性增加。双相钢的扩孔性能随着材料强度的提高呈下降的趋势。DP500与DP450和DP600相比,抗拉强度(579 MPa)居中,伸长率最高,但由于其马氏体形态和分布的差异,其扩孔性能反而最低。结论双相钢的扩孔性能会受到马氏体的含量、尺寸、形态和分布的影响,与材料强度和伸长率没有必然的关系,当马氏体呈颗粒状均匀分布时,具有更好的扩孔性能。
The paper aims to avoid flanging or hole-expansion in forming dual-phase steel to improve the productivity. Uniaxial tensile test and hole-expansion test for several dual-phase steels between 450 MPa and 789 MPa were carried out. Effects of microstructure on mechanical properties of dual-phase steels were analyzed. The yield strength for 450~780 MPa dual-phase steels increased with the reduction of ferrite's grain size. The ultimate tensile strength increased almost linearly with the increase of martensite's volume fraction. Compared with DP450 and DP600, DP500 had an intermediate ultimate tensile strength(579 MPa) and a maximum elongation; but for the difference of martensite's shape and distribution, it had a minimum hole-expansion ratio. The hole-expansion ability of dual-phase steel was mainly affected by total volume fraction, size, shape and distribution of martensite particle rather than strength and elongation of material. Uniform distribution of globular martensite particle indicates better hole-expansion ability.
The paper aims to avoid flanging or hole-expansion in forming dual-phase steel to improve the productivity. Uniaxial tensile test and hole-expansion test for several dual-phase steels between 450 MPa and 789 MPa were carried out. Effects of microstructure on mechanical properties of dual-phase steels were analyzed. The yield strength for 450~780 MPa dual-phase steels increased with the reduction of ferrite's grain size. The ultimate tensile strength increased almost linearly with the increase of martensite's volume fraction. Compared with DP450 and DP600, DP500 had an intermediate ultimate tensile strength(579 MPa) and a maximum elongation; but for the difference of martensite's shape and distribution, it had a minimum hole-expansion ratio. The hole-expansion ability of dual-phase steel was mainly affected by total volume fraction, size, shape and distribution of martensite particle rather than strength and elongation of material. Uniform distribution of globular martensite particle indicates better hole-expansion ability.
引文
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[10]祝洪川,雷泽红,吴青松.DP600的组织对成形性能的影响[J].钢铁研究,2013,41(2):32—36.ZHU Hong-chuan,LEI Ze-hong,WU Qing-song.Influence of Microstructure of DP600 on Formability[J].Research on Iron&Steel,2013,41(2):32—36.
[11]雷毅,许晓锋,余圣甫.面向高性能结构材料的超细晶粒钢研究现状及发展方向[J].中国石油大学学报(自然科学版),2007,31(2):154—162.LEI Yi,XU Xiao-feng,YU Sheng-fu.Present Status and Developmental Direction of High Performance Structural Material-oriented Ultra-fine Grained Steel[J].Journal of China University of Petroleum,2007,31(2):154—162.
[2]OSCAR Rene Terrazas,KIP Owen Findley,CHESTER John Van Tyne.Influence of Martensite Morphology on Sheared-Edge Formability of Dual-Phase Steels[J].ISIJ International,2017,57(5):937—944.
[3]KOHEI Hasegawa,KENJI Kawamura,TOSHIAKI Urabe,et al.Effects of Microstructure on Stretch-flange-formability of 980 MPa Grade Cold-rolled Ultra High Strength Steel Sheets[J].ISIJ International,2004,44(3):603—608.
[4]祝洪川,孙宜强,吴青松.先进高强钢断裂性能研究[J].锻压技术,2015,40(12):115—119.ZHU Hong-chuan,SUN Yi-qiang,WU Qing-song.Study on the Fracture Performance of AHSS[J].Forging&Stamping Technology,2015,40(12):115—119.
[5]MONDAL D K,DEY R M.Effect of Grain Size on the Microstructure and Mechanical Properties of a C-Mn-V Dual-phase Steel[J].Materials Science and Engineering A,1992,149:173—181.
[6]KIM N J,THOMAS G.Effects of Morphology on the Mechanical Behavior of Dual Phase Fe/2Si/0.1C Steel[J].Metallurgical Transactions A,1981,12(3):483—489.
[7]CORINNA Thomser,VITOON Uthaisangsuk,WOLFGANG Bleck.Influence of Martensite Distribution on the Mechanical Properties of Dual Phase Steels:Experiments and Simulation[J].Materials Technology,2009,80(8):582—587.
[8]PENG-HENG C A,PREBAN G.The Effect of Ferrite Grain Size and Martensite Volume Fraction on the Tensile Properties of Dual Phase Steel[J].Acta Mefall,1985,33(5):897—903.
[9]IRINA Pushkareva,SéBASTIEN Allain,COLIN Scott,et al.Relationship between Microstructure,Mechanical Properties and Damage Mechanisms in High Martensite Fraction Dual Phase Steels[J].ISIJ International,2015,55(10):2237—2246.
[10]祝洪川,雷泽红,吴青松.DP600的组织对成形性能的影响[J].钢铁研究,2013,41(2):32—36.ZHU Hong-chuan,LEI Ze-hong,WU Qing-song.Influence of Microstructure of DP600 on Formability[J].Research on Iron&Steel,2013,41(2):32—36.
[11]雷毅,许晓锋,余圣甫.面向高性能结构材料的超细晶粒钢研究现状及发展方向[J].中国石油大学学报(自然科学版),2007,31(2):154—162.LEI Yi,XU Xiao-feng,YU Sheng-fu.Present Status and Developmental Direction of High Performance Structural Material-oriented Ultra-fine Grained Steel[J].Journal of China University of Petroleum,2007,31(2):154—162.