高碳钢丝冷拔中的组织演变和强化机理研究
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摘要
利用透射电子显微镜、X射线衍射仪对不同冷拔应变量下70钢丝的珠光体片层间距、渗碳体片层厚度、位错密度以及抗拉强度进行了测定。结果表明,随着真应变从0增加到1.24,珠光体平均片层间距由140 nm减小至70 nm,渗碳体平均片层厚度由37 nm减小至20 nm,位错密度由8.4×10~(13)m~(-2)增加到1.3×10~(15)m~(-2),抗拉强度则由1168 MPa增加到1545 MPa,铁素体晶粒内部形成<110>丝织构。基于金属材料经典强化理论和模型,分别计算出不同应变下位错强化和边界强化对钢丝总强度的贡献。结果表明,边界强化为最主要强化机制,其次为位错强化;当应变为1.24时,边界强化、位错强化分别达到1096 MPa和333 MPa。
The pearlite lamellar spacing, cementite lamellar thickness, dislocation density and tensile strength of 70 steel wire with different cold drawing strains were measured by transmission electron microscope and X ray diffractometer. The results show that with the increase of true strain form 0 to 1.24, the average lamellar spacing of pearlite decreases from 140 nm to70 nm, the average lamellar thickness of cementite decreases from 37 nm to 20 nm, and the dislocation density increases from 8.4×10~(13)m~(-2) to 1.3×10~(15)m~(-2). The tensile strength increases from 1168 MPa to 1545 MPa. The <110> wire texture is formed in ferrite grains. Based on the classical strengthening theory and model of metal materials, the contribution of dislocation strengthening and boundary strengthening to the total strength of the steel wire under different strains was calculated respectively. The results show that boundary strengthening is the most important strengthening mechanism, and the second is dislocation strengthening. When the strain is 1.24, the boundary strengthing and dislocation strengthening reach 1096 MPa and 333 MPa, respectively.
The pearlite lamellar spacing, cementite lamellar thickness, dislocation density and tensile strength of 70 steel wire with different cold drawing strains were measured by transmission electron microscope and X ray diffractometer. The results show that with the increase of true strain form 0 to 1.24, the average lamellar spacing of pearlite decreases from 140 nm to70 nm, the average lamellar thickness of cementite decreases from 37 nm to 20 nm, and the dislocation density increases from 8.4×10~(13)m~(-2) to 1.3×10~(15)m~(-2). The tensile strength increases from 1168 MPa to 1545 MPa. The <110> wire texture is formed in ferrite grains. Based on the classical strengthening theory and model of metal materials, the contribution of dislocation strengthening and boundary strengthening to the total strength of the steel wire under different strains was calculated respectively. The results show that boundary strengthening is the most important strengthening mechanism, and the second is dislocation strengthening. When the strain is 1.24, the boundary strengthing and dislocation strengthening reach 1096 MPa and 333 MPa, respectively.
引文
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[21]Embury J D,Fisher RM.The structure and properties of drawn pearlite[J].Acta Metallurgica,1966,14:147-159.
[22]崔忠圻,覃耀春.金属学与热处理[M].北京:机械工业出版社,2008:180-183.
[2]Fu Wantang,Xiong Yi,Zhao Jun,et al.Microstructural evolution of pearlite in eutectoid Fe-C alloys during severe cold rolling[J].Journal of Materials Science and Technology,2005,21(1):25-27.
[3]张晓丹,Godfrey A,刘伟,等.珠光体钢丝冷拔过程中微观组织及铁素体微区取向与织构演变[J].金属学报,2010,46(2):141-146.
[4]赵天章,宋鸿武,张光亮.拉拔过程中珠光体钢丝心部的织构演化规律及其对力学性能的影响[J].金属学报,2014,50(6):667-673.
[5]胡显军,谢俊,周立初,等.渗碳体形态对珠光体钢丝拉拔形变的影响[J].钢铁研究学报,2018,30(2):120-126.
[6]张必明,赵宇飞,方峰,等.冷拉SAE1008低碳钢丝强化机制的探讨[J].材料热处理学报,2014,35(1):115-119.
[7]Embury J D,Fisher R M.The structure and properties of drawn pearlite[J].Acta Metallurgica,1966,14:147-159.
[8]Langford G.Deformation of pearlite[J].Metall Trans,1977,8A:861-863.
[9]Nishida S,Yoshie A,Imagumbal M.Work hardening of hypereutectoid and eutectoid steels during drawing[J].ISIJInternational,1998,38(2):177-186.
[10]Zelin M.Microstructure evolution in pearlitic steels during wire drawing[J].Acta Materialia,2002,50:4431-4447.
[11]Borchers Christine,Kirchheim Reiner.Cold-drawn pearlitic steel wires[J].Progress in Materials Science,2016,82:405-444.
[12]Williamson G K,Smallman RE.Dislocation densities in some annealed and cold-worked metals from measurementas on the X-ray Debye-Scherrer spectrum[J].Philosophical Magazine,1955,1:34-46.
[13]Williamson G K,Hall W H.X-ray line broadening from filed aluminium and wolfram[J].Acta Metallurgica,1953,1(1):22-31.
[14]倪海涛,张喜燕,朱玉涛.纳米结构位错的研究进展[J].材料导报,2010,24(6):112-115.
[15]Langford G.Deformation of pearlite[J].Metallurgical and Materials Transactions A,1977,8(6):861-875.
[16]Zhang X D,Godfrey A,Hansen N.Evolution of cementite morphology in pearlitic steel wire during wet wire drawing[J].Materials Characterization,2010,61:65-72.
[17]Embury J D,Fisher R M.The Structure and properties of drawn pearlite[J].Acta Metallurgical,1966,14:147-159.
[18]Zhang X D,Godfrey A,Huang X X,et al.Microstructure and strengthening mechanisms in cold-drawn pearlitic steel wire[J].Acta Materialia,2011,59:3422-3430.
[19]Zhang X D,Hansen N,Godfrey A,et al.Dislocation-based plasticity and strengthening mechanisms in sub-20 nm lamellar structures in pearlitic steel wire[J].Acta Materialia,2016,114:176-183.
[20]Hansen N.Boundary strengthening in undeformed and deformed polycrystals[J].Materials Science and Engineering A,2005,409(1/2):39-45.
[21]Embury J D,Fisher RM.The structure and properties of drawn pearlite[J].Acta Metallurgica,1966,14:147-159.
[22]崔忠圻,覃耀春.金属学与热处理[M].北京:机械工业出版社,2008:180-183.