硼铬微合金钢的脆性断裂失效分析
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摘要
为了研究硼铬微合金钢的脆性断裂失效机理,以工厂履带拖拉机支重轮的中心轴脆性断裂为研究背景,通过对中心轴断口的观察以及不同位置的组织和晶粒度的对比,得出了硼铬微合金钢的断裂失效机理。利用FactSage和Thermo-Calc软件对TiN夹杂物的析出机理和控制进行理论计算。结果表明,钛合金的不完全溶解和钛、氮元素质量分数的不合理控制,导致大量的大尺寸硬质TiN夹杂物在凝固过程中析出,使得钛元素的加入没有起到很好地细化晶粒的效果,中心区域的铁素体+奥氏体组织的晶粒度过于粗大。大尺寸TiN夹杂物作为裂纹源和心部粗大的晶粒导致了硼铬微合金钢的脆性断裂失效。热力学计算表明,TiN夹杂物在凝固过程中形成,低钛低氮和钛、氮质量分数的合理搭配可以有效推迟TiN夹杂物的析出,降低其尺寸。较小的夹杂物尺寸和细小的晶粒均可以有效增强材料抵抗裂纹扩展的能力。
In order to identify the fracture failure of B-Cr microalloyed steel,the brittle fracture of track roller during the operation of tracking tractor was taken as the research background.The fracture failure of TiN inclusion on B-Cr microalloyed steel was studied by observing the fracture surface of the central axis and comparing the microstructure and grain size at different positions.The FactSage and Thermo-Calc software were used to calculate the formation and control mechanism of TiN inclusion.The results were as follows.Due to the incomplete dissolution of Ti alloy and irrational control of Ti and N mass fraction in the molten steel,lots of large-size TiN inclusions were formed during the solidification of B-Cr micro-alloyed steel.The addition of Ti element did not play agood role in refining grain,resulting in the large grain size in the center,and further reducing the impact property of B-Cr microalloyed steel.Large-size TiN inclusion acted as the crack origin and the large grain size led to the brittle fracture of B-Cr microalloyed steel.Thermodynamic calculation showed that the TiN inclusion formed during the solidification process and the precipitation temperature of TiN can be effectively delayed with low Ti and N mass fraction in molten steel.Small inclusion size and fine grain size can effectively enhance the crack resistance of the material.
In order to identify the fracture failure of B-Cr microalloyed steel,the brittle fracture of track roller during the operation of tracking tractor was taken as the research background.The fracture failure of TiN inclusion on B-Cr microalloyed steel was studied by observing the fracture surface of the central axis and comparing the microstructure and grain size at different positions.The FactSage and Thermo-Calc software were used to calculate the formation and control mechanism of TiN inclusion.The results were as follows.Due to the incomplete dissolution of Ti alloy and irrational control of Ti and N mass fraction in the molten steel,lots of large-size TiN inclusions were formed during the solidification of B-Cr micro-alloyed steel.The addition of Ti element did not play agood role in refining grain,resulting in the large grain size in the center,and further reducing the impact property of B-Cr microalloyed steel.Large-size TiN inclusion acted as the crack origin and the large grain size led to the brittle fracture of B-Cr microalloyed steel.Thermodynamic calculation showed that the TiN inclusion formed during the solidification process and the precipitation temperature of TiN can be effectively delayed with low Ti and N mass fraction in molten steel.Small inclusion size and fine grain size can effectively enhance the crack resistance of the material.
引文
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[19] YANG L,CHENG G,LI S,et al.Generation mechanism of TiN inclusion for GCr15SiMn during electroslag remelting process[J].ISIJ International,2015,55(9):1901.
[20]万响亮,李光强,吴开明.原位观察TiN粒子对低合金高强度钢模拟焊接热影响区粗晶区晶粒细化作用[J].工程科学学报,2016,38(3):371.
[21]张朋彦,燕际军,高彩茹,等.含钛夹杂物对大热输入焊接用钢HAZ韧性的影响[J].钢铁,2012,47(11):79.
[22] Medina S F,Chapa M,Valles P,et al.Influence of Ti and N contents on austenite grain control and precipitate size in structural steels[J].ISIJ International,1999,39(9):930.
[23] Zhu Z X,Marimuthu M,Kuzmikova L,et al.Influence of Ti/N ratio on simulated CGHAZ microstructure and toughness in X70steels[J].Science and Technology of Welding and Joining,2013,18(1):45.
[24] Echeverri A,Rodriguez-Ibabe J M.The role of grain size in brittle particle induced fracture of steels[J].Materials Science and Engineering:A,2003,346(1):149.
[25] Du J,Strangwood M,Davis C L.Effect of TiN particles and grain size on the charpy impact transition temperature in steels[J].Journal of Materials Science and Technology,2012,28(10):878.
[2] ZHU Y,LI B,LIU P.Effect of annealing and hot rolling on grain boundary segregation of arsenic in an Mn-steel microalloyed by Ti,Cr and Nb[J].Journal of Iron and Steel Research,International,2013,20(9):67.
[3] Fadel A,Gli3ic'D,Radovic'N,et al.Influence of Cr,Mn and Mo addition on structure and properties of V microalloyed medium carbon steels[J].Journal of Materials Science and Technology,2012,28(11):1053.
[4] PAN T,CHAI X,WANG J,et al.Precipitation behavior of VN microalloyed steels during normalizing[J].Journal of Iron and Steel Research,International,2015,22(11):1037.
[5]师仲然,王瑞珍,王青峰,等.钒微合金钢粗晶热影响区的组织和韧性[J].钢铁,2015,50(4):70.
[6]李冰,郑磊,崔天成,等.钼、铬对低碳铌钛微合金钢连续冷却转变行为的影响[J].钢铁,2011,46(10):80.
[7]王壮飞,石明浩,陈俊,等.钒和铌-钒低碳微合金钢的静态再结晶行为[J].钢铁,2018,53(4):62.
[8]杨忠民,王凯,孙秀,等.铌钛微合金钢铸坯晶界铁素体形貌与晶界裂纹[J].钢铁,2018,53(11):70.
[9]吴俊平,靳星,龙木军,等.含钛微合金钢低温冲击韧性波动的原因与改进[J].中国冶金,2017,27(12):59.
[10]高志玉,潘涛,王卓,等.高淬透性硼微合金化特厚板钢成分优化设计[J].工程科学学报,2015,37(4):447.
[11]马莉,王毛球,徐香秋,等.铌硼微合金化齿轮钢的晶粒尺寸及淬透性[J].材料热处理学报,2009,30(5):74.
[12] WANG Y,BAO Y,WANG M,et al.Precipitation behavior of BN type inclusions in 42CrMo steel[J].International Journal of Minerals,Metallurgy,and Materials,2013,20(1):28.
[13] Tomita Y,Saito N,Tsuzuki T,et al.Improvement in HAZ toughness of steel by TiN-MnS addition[J].ISIJ International,1994,34(10):829.
[14] Yasuhide O,Okamura Y,Matsuda S,et al.Characteristics of HAZ microstructure in Ti-B treated steel for large heat input welding[J].Tetsu-to-Hagané,1987,73(8):1010.
[15]易顺,陶勇,阮方,等.帘线钢凝固过程中钛和氮偏析及TiN夹杂尺寸计算[J].钢铁,2016,51(4):70.
[16] Balart M J,Davis C L,Strangwood M.Cleavage initiation in Ti-V-N and V-N microalloyed ferritic-pearlitic forging steels[J].Materials Science and Engineering:A,2000,284(1):1.
[17] YAN W,SHAN Y Y,YANG K.Effect of TiN inclusions on the impact toughness of low-carbon microalloyed steels[J].Metallurgical and Materials Transactions:A,2006,37(7):2147.
[18] YAN W,SHAN Y Y,YANG K.Influence of TiN inclusions on the cleavage fracture behavior of low-carbon microalloyed steels[J].Metallurgical and Materials Transactions:A,2007,38(6):1211.
[19] YANG L,CHENG G,LI S,et al.Generation mechanism of TiN inclusion for GCr15SiMn during electroslag remelting process[J].ISIJ International,2015,55(9):1901.
[20]万响亮,李光强,吴开明.原位观察TiN粒子对低合金高强度钢模拟焊接热影响区粗晶区晶粒细化作用[J].工程科学学报,2016,38(3):371.
[21]张朋彦,燕际军,高彩茹,等.含钛夹杂物对大热输入焊接用钢HAZ韧性的影响[J].钢铁,2012,47(11):79.
[22] Medina S F,Chapa M,Valles P,et al.Influence of Ti and N contents on austenite grain control and precipitate size in structural steels[J].ISIJ International,1999,39(9):930.
[23] Zhu Z X,Marimuthu M,Kuzmikova L,et al.Influence of Ti/N ratio on simulated CGHAZ microstructure and toughness in X70steels[J].Science and Technology of Welding and Joining,2013,18(1):45.
[24] Echeverri A,Rodriguez-Ibabe J M.The role of grain size in brittle particle induced fracture of steels[J].Materials Science and Engineering:A,2003,346(1):149.
[25] Du J,Strangwood M,Davis C L.Effect of TiN particles and grain size on the charpy impact transition temperature in steels[J].Journal of Materials Science and Technology,2012,28(10):878.