不同片层厚度TC4合金的原位拉伸变形行为
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摘要
将TC4合金加热到相变点以上,经不同冷却方式冷却后获得了不同厚度的α相片层组织,用扫描电镜观察了不同片层厚度TC4钛合金在室温下的原位拉伸变形过程;使用原子力显微镜和激光共聚焦显微镜分别观察了拉伸变形后的滑移情况和断口的3D形貌。结果表明:TC4钛合金在热处理过程中,冷速越快,α片层越薄;在塑性变形阶段,厚薄两种片层组织中的滑移剪切带与拉伸方向呈大约45°角;拉伸加载初期,微裂纹萌生于试样缺口处,随着载荷的增加次生裂纹易产生于α/β相界,然后相互连接形成主裂纹;厚片层试样中裂纹主要沿相界和穿层的方式扩展,薄片层试样中裂纹扩展主要以穿层方式为主;厚片层试样的拉伸断口中存在着较多解理面以及撕裂棱,主要是解理断裂,而薄片层试样断口中有少量韧窝和解理面,主要是准解理断裂。
The microstructure of α phase with different lamellar thickness of TC4 titanium alloy was obtained after heating above the phase transition point then cooling with different cooling rates. The in-situ tensile deformation process of the TC4 titanium alloy with different lamellar thickness at room temperature was observed by scanning electron microscopy(SEM). Atomic force microscopy(AFM) and laser confocal microscopy(LSCM) were used to observe the slip after tensile deformation and the 3 D morphology of fracture surface, respectively. The results show that the faster the cooling rate is, the thinner the α-lamellar is in the process of heat treatment of TC4 titanium alloy, and in the plastic deformation stage, the slip shear band and the tensile direction of the two kinds of lamellar structure are about 45°. At the initial stage of tensile loading, the micro-cracks occur at the notch of the specimen, and the secondary cracks tend to occur at the α/β phase boundary with the increase of load, and then the main cracks are formed by joining each other. In the thick α-lamellar specimen, the crack mainly propagates along the phase boundary and traverse the lamellar, and the crack propagation in the thin lamellar specimen is mainly to traverse the lamellar. There are many cleavage planes and tearing ribs in the tensile fracture of the thick lamellar specimen, mainly cleavage fracture, while there are a few dimples and cleavage planes in the fracture surface of the thin lamellar specimen, mainly quasi-cleavage fracture.
The microstructure of α phase with different lamellar thickness of TC4 titanium alloy was obtained after heating above the phase transition point then cooling with different cooling rates. The in-situ tensile deformation process of the TC4 titanium alloy with different lamellar thickness at room temperature was observed by scanning electron microscopy(SEM). Atomic force microscopy(AFM) and laser confocal microscopy(LSCM) were used to observe the slip after tensile deformation and the 3 D morphology of fracture surface, respectively. The results show that the faster the cooling rate is, the thinner the α-lamellar is in the process of heat treatment of TC4 titanium alloy, and in the plastic deformation stage, the slip shear band and the tensile direction of the two kinds of lamellar structure are about 45°. At the initial stage of tensile loading, the micro-cracks occur at the notch of the specimen, and the secondary cracks tend to occur at the α/β phase boundary with the increase of load, and then the main cracks are formed by joining each other. In the thick α-lamellar specimen, the crack mainly propagates along the phase boundary and traverse the lamellar, and the crack propagation in the thin lamellar specimen is mainly to traverse the lamellar. There are many cleavage planes and tearing ribs in the tensile fracture of the thick lamellar specimen, mainly cleavage fracture, while there are a few dimples and cleavage planes in the fracture surface of the thin lamellar specimen, mainly quasi-cleavage fracture.
引文
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[22] 欧阳德来,杜海明,鲁世强,等.β热处理工艺对Ti-6Al-2Zr-1Mo-1V钛合金片层组织演变的影响[J].材料热处理学报,2016,37(12):42-46.OUYANG De-lai,DU Hai-ming,LU Shi-qiang,et al.Influence of β heat treatment on lamellar microstructure evolution of Ti-6Al-2Zr-1Mo-1V alloy[J].Transactions of Materials and Heat Treatment,2016,37(12):42-46.
[23] Shao H,Zhao Y,Ge P,et al.In-situ SEM observations of tensile deformation of the lamellar microstructure in TC21 titanium alloy[J].Materials Science and Engineering A,2013,559:515-519.
[24] 李保元,赵清.超高锰钢原位拉伸断裂及机理分析[J].热加工工艺,2016,45(14):36-38.LI Bao-yuan,ZHAO qing.In-situ tension fracture of super-high Mn steel and mechanism analysis[J].Hot Working Technology,2016,45(14):36-38.
[25] 陆严清.塑性变形理论及应用[M].北京:国防工业出版社,1988.
[26] Partridge P G.The crystallography and deformation modes of hexagonal close-packed metals[J].Metallurgical Reviews,1967,12(1):169-194.
[27] Eshelby J D,Frank F C,Nabarro F R N.The equilibrium of linear arrays of dislocations[J].Philosophical Magazine,1951,42(327):351-364.
[28] 赵光菊,钟蜀晖,邓建华.TA6V钛合金疲劳小裂纹扩展行为研究[J].贵州大学学报:自然科学版,2009,26(3):72-76.ZHAO Guang-ju,ZHONG Shu-hui,DENG Jian-hua.Study on the fatigue small crack growth behavior in TA6V titanium alloy[J].Journal of Guizhou University(Natural Science),2009,26(3):72-76.
[29] 薛丁琪.TC11钛合金塑性加工裂纹形成及其机理的研究[D].哈尔滨:哈尔滨工业大学,2008.XUE Ding-qi.The study on the crack initlates and propagates mechanism of TC11 alloy in the forging processing[D].Harbin:Harbin Institute of Technology,2008.
[30] 钟群鹏,赵子华,张峥.断口学的发展及微观断裂机理研究[J].机械强度,2005,27(3):358-370.ZHONG Qun-peng,ZHAO Zi-hua,ZHANG Zheng.Development of “fractography” and research of fracture micromechanism[J].Journal of Mechanical Strength,2005,27(3):358-370.
[2] Chang M C,Luo C W,Huang M S,et al.High-temperature microstructural characteristics of a novel biomedical titanium alloy[J].Journal of Alloys and Compounds,2010,499(2):171-175.
[3] Luan J H,Jiao Z B,Chen G,et al.Improved ductility and oxidation resistance of cast Ti-6Al-4V alloys by microalloying[J].Journal of Alloys and Compounds,2014,602:235-240.
[4] Yang,F,Gabbitas,B.Feasibility of producing Ti-6Al-4V alloy for engineering application by powder compact extrusion of blended elemental powder mixtures[J].Journal of Alloys and Compounds,2017,695:1455-1461.
[5] 赵光菊,郭献忠,毛宗良,等.Ti6A14V高锁螺栓疲劳断口形貌及断口分析[J].贵州大学学报:自然科学版,2012,29(3):50-52.ZHAO Guang-ju,GUO Xian-zhong,MAO Zong-liang,et al.Study on the fatigue fracture of hi-lock pins in Ti6A14V titanium alloy[J].Journal of Guizhou University:Natural Science,2012,29(3):50-52.
[6] Oh J,Kim N J,Lee S,et al.Correlation of fatigue properties and microstructure in investment cast Ti-6Al-4V welds[J].Materials Science and Engineering A,2003,340(1/2):232-242.
[7] Filip R,Kubiak K,Ziaja W,et al.The effect of microstructure on the mechanical properties of two-phase titanium alloys[J].Journal of Materials Processing Technology,2003,133(1/2):84-89.
[8] Ivasishin O M,Markovsky P E,Matviychuk Y V,et al.A comparative study of the mechanical properties of high-strength β-titanium alloys[J].Journal of Alloys and Compounds,2008,457(1/2):0-309.
[9] Guo P,Zhao Y Q,Zeng W D.Fatigue crack growth behavior in TC4-DT titanium alloy with different lamellar microstructures[J].Rare Metal Materials and Engineering,2015,44(2):277-281.
[10] 马英杰,刘建荣,雷家峰,等.TC4ELI合金疲劳裂纹尖端塑性区对裂纹扩展的影响[J].中国有色金属学报,2009,19(10):1789-1794.MA Ying-jie,LIU Jian-rong,LEI Jia-feng,et al.Influence of fatigue crack tip plastic zone on crack propagation behavior in TC4ELI alloy[J].The Chinese Journal of Nonferrous Metals,2009,19(10):1789-1794.
[11] 党薇,薛祥义,李金山,等.TC21合金片层组织特征对其断裂韧性的影响[J].中国有色金属学报,2010,20(S1):16-20.DANG Wei,XUE Xiang-yi,LI Jin-shan,et al.Influence of lamellar microstructure feature on fracture toughness of TC21 alloy[J].The Chinese Journal of Nonferrous Metals,2010,20(S1):16-20.
[12] 靳丹,程兴旺,郑超,等.片层宽度对TC21钛合金动态压缩性能及其绝热剪切敏感性的影响规律[J].稀有金属材料与工程,2016,45(11):2953-2958.JIN Dan,CHENG Xing-wang,ZHENG Chao,et al.Effects of lamellar α thickness on dynamic mechanical properties and sensitivity to adiabatic shear banding of TC21 alloy[J].Rare Metal Materials and Engineering,2016,45(11):2953-2958.
[13] 陈煜,孙宁,李宏周,等.原位加载扫描电镜技术及应用[J].化工新型材料,2012,40(2):43-45.CHEN Yu,SUN Ning,LI Hong-zhou,et al.Progress and application of the in-situ SEM technique[J].New Chemical Material,2012,40(2):43-45.
[14] Zhang X,Zhang S,Zhao Y,et al.In-situ observations of the tensile deformation and fracture behavior of a fine-grained titanium alloy sheet[J].Journal of Alloys and Compounds,2018,740:660-668.
[15] Shao H,Zhao Y,Ge P,et al.Crack initiation and mechanical properties of TC21 titanium alloy with equiaxed microstructure[J].Materials Science and Engineering A,2013,586:215-222.
[16] Boehlert C J,Cowen C J,Tamirisakandala S,et al.In situ scanning electron microscopy observations of tensile deformation in a boron-modified Ti-6Al-4V alloy[J].Scripta Materialia,2006,55(5):465-468.
[17] 单迪,何鑫玉,王睿,等.TC21钛合金片层组织裂纹萌生和扩展的原位研究[J].兵器材料科学与工程,2015,38(6):20-22.SHAN Di,HE Xin-yu,WANG Rui,et al.In-situ study of crack initiation and propagation of lamellar microstructure in TC21 titanium alloy[J].Ordnance Material Science and Engineering,2015,38(6):20-22.
[18] Peng X,Guo H,Shi Z,et al.Study on the hot deformation behavior of TC4-DT alloy with equiaxed α+β starting structure based on processing map[J].Materials Science and Engineering A,2014,605:80-88.
[19] Lunt D,Fonseca J Q D,Rugg D,et al.Microscopic strain localisation in Ti-6Al-4V during uniaxial tensile loading[J].Materials Science and Engineering A,2017,680:444-453.
[20] Kim Y,Song Y B,Lee S H.Microstructure and intermediate-temperature mechanical properties of powder metallurgy Ti-6Al-4V alloy prepared by the prealloyed approach[J].Journal of Alloys and Compounds,2015,637:234-241.
[21] 李壮,康少酺,于欢欢,等.TC4钛合金冷却过程中组织变化分析[J].沈阳航空航天大学学报,2014,31(5):44-49.LI Zhuang,KANG Shao-pu,YU Huan-huan,et al.The microstructural evolution of TC4 alloy during cooling fromthe solution temperature[J].Journal of Shenyang Aerospace University,2014,31(5):44-49.
[22] 欧阳德来,杜海明,鲁世强,等.β热处理工艺对Ti-6Al-2Zr-1Mo-1V钛合金片层组织演变的影响[J].材料热处理学报,2016,37(12):42-46.OUYANG De-lai,DU Hai-ming,LU Shi-qiang,et al.Influence of β heat treatment on lamellar microstructure evolution of Ti-6Al-2Zr-1Mo-1V alloy[J].Transactions of Materials and Heat Treatment,2016,37(12):42-46.
[23] Shao H,Zhao Y,Ge P,et al.In-situ SEM observations of tensile deformation of the lamellar microstructure in TC21 titanium alloy[J].Materials Science and Engineering A,2013,559:515-519.
[24] 李保元,赵清.超高锰钢原位拉伸断裂及机理分析[J].热加工工艺,2016,45(14):36-38.LI Bao-yuan,ZHAO qing.In-situ tension fracture of super-high Mn steel and mechanism analysis[J].Hot Working Technology,2016,45(14):36-38.
[25] 陆严清.塑性变形理论及应用[M].北京:国防工业出版社,1988.
[26] Partridge P G.The crystallography and deformation modes of hexagonal close-packed metals[J].Metallurgical Reviews,1967,12(1):169-194.
[27] Eshelby J D,Frank F C,Nabarro F R N.The equilibrium of linear arrays of dislocations[J].Philosophical Magazine,1951,42(327):351-364.
[28] 赵光菊,钟蜀晖,邓建华.TA6V钛合金疲劳小裂纹扩展行为研究[J].贵州大学学报:自然科学版,2009,26(3):72-76.ZHAO Guang-ju,ZHONG Shu-hui,DENG Jian-hua.Study on the fatigue small crack growth behavior in TA6V titanium alloy[J].Journal of Guizhou University(Natural Science),2009,26(3):72-76.
[29] 薛丁琪.TC11钛合金塑性加工裂纹形成及其机理的研究[D].哈尔滨:哈尔滨工业大学,2008.XUE Ding-qi.The study on the crack initlates and propagates mechanism of TC11 alloy in the forging processing[D].Harbin:Harbin Institute of Technology,2008.
[30] 钟群鹏,赵子华,张峥.断口学的发展及微观断裂机理研究[J].机械强度,2005,27(3):358-370.ZHONG Qun-peng,ZHAO Zi-hua,ZHANG Zheng.Development of “fractography” and research of fracture micromechanism[J].Journal of Mechanical Strength,2005,27(3):358-370.