残留奥氏体对微纳贝氏体钢塑韧性的影响
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摘要
采用高碳和中碳低温贝氏体转变工艺(0.95C钢为200℃等温10 d,0.30C钢为320℃等温1 d)研究了残留奥氏体对微纳结构钢塑韧性的影响,对不同试样的显微组织、各相体积分数、伸长率和冲击韧性进行观察、检测和分析。试验结果表明,中碳钢贝氏体转变的塑韧性明显高于高碳钢贝氏体转变,主要原因是中碳钢贝氏体转变中存在一定的亚微米级薄膜状残留奥氏体,在拉伸或冲击过程中引起的残留奥氏体的塑性变形,使断裂的能量增加,可以显著提高样品的塑韧性。
The effect of retained austenite on the plasticity and toughness in micro/nano-structured steels was analyzed by high and medium carbon bainitic transformation processes(200 ℃ for 10 days in 0.95 C and 320 ℃ for 1 day in 0.30 C steel). The microstructure, phase fraction, elongation and impact toughness of different steels were observed, detected and analyzed. The results show that the plasticity and impact properties of medium-carbon bainitic transformation were significantly higher than those of high-carbon bainitic transformation. The main reason is that some retained austenite in shape of sub-micron film is formed in medium-carbon bainitic transformation. The plastic deformation of the retained austenite in the stretching or impact process can significantly improve the plasticity and toughness of the steel since the fracture energy was increased.
The effect of retained austenite on the plasticity and toughness in micro/nano-structured steels was analyzed by high and medium carbon bainitic transformation processes(200 ℃ for 10 days in 0.95 C and 320 ℃ for 1 day in 0.30 C steel). The microstructure, phase fraction, elongation and impact toughness of different steels were observed, detected and analyzed. The results show that the plasticity and impact properties of medium-carbon bainitic transformation were significantly higher than those of high-carbon bainitic transformation. The main reason is that some retained austenite in shape of sub-micron film is formed in medium-carbon bainitic transformation. The plastic deformation of the retained austenite in the stretching or impact process can significantly improve the plasticity and toughness of the steel since the fracture energy was increased.
引文
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[15] 谢振家.高性能低合金钢中残余奥氏体调控机理及性能研究[D]//北京: 北京科技大学,2016.(Xie J Z.Control mechanism retained austenite and properties in high performance low alloy steels[D]//Beijing: University of Science and Technology Beijing,2016.)
[16] Caballero F G,Miller M K,Babu S S,et al.Atomic scale observations of bainite transformation in a high carbon high silicon steel[J].Acta Materialia,2007,55(1):381.
[17] Tsukatani I,Hashimoto S,Inoue T.Effects of silicon and manganese addition on mechanical properties of high strength hot-rolled sheet steel containing retained austenite[J].ISIJ International,1991,31(9):992.
[18] 戴品强,何则荣,毛志远.奥氏体-贝氏体球墨铸铁断裂的微观过程及强韧化机理[J].钢铁研究学报,2001,13(6):47.(Dai P Q,He Z R,Mao Z Y.Micro-process of fracture and mechanism of strengthening,toughening for austempered ductile iron[J].Journal of Iron and Steel Research,2001,13(6): 47.)
[2] Bhadeshia H K D H.Nanostructured bainite[J].Proceedings of the Royal Society,2010,466A(5):3.
[3] Caballero F G,Bhadeshia H K D H.Very strong bainite[J].Current Opinion in Solid and Materials Science,2004(8):251.
[4] Timokhina I B,Beladi H,Xiong X Y,et al.Nanoscale microstructural characterization of a nanobainitic steel[J].Acta Materialia,2011,59(4):5511.
[5] Tsai Y T,Chang H T,Huang B M,et al.Microstructural characterization of Charpy-impact-tested nanostructured bainite[J].Materials Characterization,2015,107(6):63.
[6] Caballero F G,Santofimia M J,García-Mateo C,et al.Theoretical design and advanced microstructure in super high strength steels[J].Materials and Design,2009,30(6):2077.
[7] Caballero F G,Chao J,Cornide J,et al.Toughness deterioration in advanced high strength bainitic steels[J].Materials Science and Engineering 2009,525A(1/2):87.
[8] Timokhina I B,Hodgson P D,Pereloma E V.Effect of microstructure on the stability of retained austenite in transformation-induced-plasticity steels[J].Metallurgical and Materials Transactions,2004,35A(8):2331.
[9] 胡锋.纳米结构双相钢中残留奥氏体微结构调控及其对力学性能的影响[D]//武汉:武汉科技大学,2014.(Hu F.Regulation mechanism of retained austenite microstructure in the nanostructured dual-phase steels and its effect on the mechanical properties[D]// Wuhan: Wuhan University of Science and Technology,2014.)
[10] Caballero F G,Garcia-Mateo C,Santofimia M J,et al.New experimental evidence on the incomplete transformation phenomenon in steel[J].Acta Materialia,2009,57(1):8.
[11] 胡立光,谢希文.钢的热处理(原理和工艺)[M].西安: 西北工业大学出版社,2004.(Hu L G,Xie X W.Heat treatment of Steel (Principle and Technology)[M].Xi′an: Northwestern Polytechnical University Press,2004.)
[12] 李麟.相变塑性钢-原理、性能、设计和应用[M].北京: 科学出版社,2009.(Li L.Phase Transformation Plastic Steel: Principle,Properties,Design and Application [M].Beijing: Science Press,2009.)
[13] Pereloma E V,Timokhina I B,Miller M K,et al.Three-dimensional atom probe analysis of solute distribution in thermo-mechanically processed TRIP steels[J].Acta Materialia,2007,55(8):2587.
[14] 陶浪,吴开明.热处理工艺对低温贝氏体钢力学及搅拌磨损性能的影响[J].钢铁研究学报,2018,30(2):144.(Tao L,Wu K M.Effect of heat treatment on mechanical and stirring wear properties of low temperature bainite steels[J].Journal of Iron and Steel Research,2018,30(2):144.)
[15] 谢振家.高性能低合金钢中残余奥氏体调控机理及性能研究[D]//北京: 北京科技大学,2016.(Xie J Z.Control mechanism retained austenite and properties in high performance low alloy steels[D]//Beijing: University of Science and Technology Beijing,2016.)
[16] Caballero F G,Miller M K,Babu S S,et al.Atomic scale observations of bainite transformation in a high carbon high silicon steel[J].Acta Materialia,2007,55(1):381.
[17] Tsukatani I,Hashimoto S,Inoue T.Effects of silicon and manganese addition on mechanical properties of high strength hot-rolled sheet steel containing retained austenite[J].ISIJ International,1991,31(9):992.
[18] 戴品强,何则荣,毛志远.奥氏体-贝氏体球墨铸铁断裂的微观过程及强韧化机理[J].钢铁研究学报,2001,13(6):47.(Dai P Q,He Z R,Mao Z Y.Micro-process of fracture and mechanism of strengthening,toughening for austempered ductile iron[J].Journal of Iron and Steel Research,2001,13(6): 47.)