ECAP挤压道次对6061铝合金力学性能及耐磨性的影响
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摘要
采用等通道转角挤压(Equal Channel Angular Pressing,ECAP)工艺,在110℃下对6061铝合金进行4道次挤压变形。借助显微硬度测试、室温拉伸试验和断口SEM分析,研究了挤压道次对6061铝合金力学性能的影响规律;通过摩擦磨损试验,获得了不同挤压道次下6061铝合金的摩擦系数以及磨损率,并对磨损表面进行了形貌观察和EDS能谱分析。结果表明:随着挤压道次的增加,6061铝合金硬度和强度逐渐增加,且前两个道次增幅最大,4道次变形后,材料晶粒得到显著细化,显微硬度和抗拉强度分别达到了93. 4 HV和250. 2 MPa;同时,显微硬度分布趋于均匀,材料塑性降低,拉伸断口表现出明显的韧性断裂特征。随着挤压道次的增加,6061铝合金耐磨性能和抗氧化能力均得到显著提升,平均摩擦系数和平均磨损率逐渐降低,分别从1道次的0. 457、0. 028 mm3·m-1下降到4道次的0. 355、0. 014 mm3·m-1。ECAP变形后6061铝合金磨损机制是以磨粒磨损和氧化剥层磨损为主导的混合磨损机制。
The equal channel angular pressing( ECAP) process was used,the four-pass extrusion deformation of 6061 aluminum alloy was conducted at 110 ℃,and the influences of ECAP passes on mechanical properties of 6061 aluminum alloy were investigated by the micro hardness measurements,tensile tests at room temperature and fracture analysis( SEM). Then,the friction coefficient and wear rate of6061 aluminum alloy under different ECAP passes were obtained by friction-wear test,and the wear surface morphology observation and energy spectrum analysis of specimen were conducted. The results show that with the increase of ECAP passes,the micro hardness and tensile strength of 6061 aluminum alloy increase,and the largest increase takes place in the first two passes. After four passes of ECAP,the grain size of material is refined significantly,and the micro hardness and tensile strength are up to 93. 4 HV and 250. 2 MPa,respectively. Moreover,the micro hardness distribution tends to be more uniform,and the material shows lower plasticity with ductile fracture.With the increase of ECAP passes,the wear resistance and oxidation resistance are greatly improved,and the average friction coefficient and wear rate decrease from 0. 457,0. 028 mm3·m-1 of the first pass to 0. 355,0. 014 mm3·m-1 of the fourth pass,respectively. Thus,the wear mechanism of 6061 aluminum alloy after ECAP process is a mixed wear mechanism dominated by abrasive wear and oxidation wear.
The equal channel angular pressing( ECAP) process was used,the four-pass extrusion deformation of 6061 aluminum alloy was conducted at 110 ℃,and the influences of ECAP passes on mechanical properties of 6061 aluminum alloy were investigated by the micro hardness measurements,tensile tests at room temperature and fracture analysis( SEM). Then,the friction coefficient and wear rate of6061 aluminum alloy under different ECAP passes were obtained by friction-wear test,and the wear surface morphology observation and energy spectrum analysis of specimen were conducted. The results show that with the increase of ECAP passes,the micro hardness and tensile strength of 6061 aluminum alloy increase,and the largest increase takes place in the first two passes. After four passes of ECAP,the grain size of material is refined significantly,and the micro hardness and tensile strength are up to 93. 4 HV and 250. 2 MPa,respectively. Moreover,the micro hardness distribution tends to be more uniform,and the material shows lower plasticity with ductile fracture.With the increase of ECAP passes,the wear resistance and oxidation resistance are greatly improved,and the average friction coefficient and wear rate decrease from 0. 457,0. 028 mm3·m-1 of the first pass to 0. 355,0. 014 mm3·m-1 of the fourth pass,respectively. Thus,the wear mechanism of 6061 aluminum alloy after ECAP process is a mixed wear mechanism dominated by abrasive wear and oxidation wear.
引文
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[2] Jin H. Improvement of superplasticity in AA5083 by equal channelangular extrusion and rolling[J]. Materials Science and Technolo-gy,2017,33(14):1696-1702.
[3] Avvari M,Narendranath S. Effect of secondary Mg17Al12 phaseon AZ80 alloy processed by equal channel angular pressing(ECAP)[J]. Silicon,2018,10(1):39-47.
[4] Khelfa T,Rekik M,Munoz B J A,et al. Microstructure andstrengthening mechanisms in an Al-Mg-Si alloy processed by equalchannel angular pressing(ECAP)[J]. International Journal ofAdvanced Manufacturing Technology, 2018, 95(1-4):1165-1177.
[5] Tanski T,Snopinski P,Hilser O. Microstructure and mechanicalproperties of two binary Al-Mg alloys deformed using equal channelangular pressing[J]. Materialwissenschaft Und Werkstofftechnik,2017,48(5):439-446.
[6] Guillard A,Zhou Q,Destech I. Effect of microstructures on corro-sion properties of CP-Ti for medical applications[A]. 3rd Interna-tional Conference on Applied Mechanics and Mechanical Automa-tion[C]. Thailand:Phuket,2017.
[7]胡玉军,李峻薇,旷军平. ECAP和轧制工艺对H65黄铜β相形态和抗拉强度的影响[J].锻压技术,2017,42(10):101-105.Hu Y J,Li J W,Kuang J P. Influences of ECAP and rollingprocess onβphase morphology and tensile strength of brass H65[J]. Forging&Stamping Technology,2017,42(3):101-105.
[8]刘满平,韦江涛,李毅超,等.等通道转角挤压Al-Mg-Si铝合金的动态时效特性和力学性能[J].材料研究学报,2016,30(10):721-730.Liu M P,Wei J T,Li Y C,et al. Dynamic aging behavior and me-chanical properties of an Al-Mg-Si aluminium alloy induced byequal channel angular pressing[J]. Chinese Journal of Materialsresearch,2016,30(10):721-730.
[9]韦江涛.超细晶6061Al-Mg-Si铝合金的力学性能和摩擦磨损行为[D].镇江:江苏大学,2016.Wei J T. Mechanical Properties and Wear Behaviors in Ultrafine-grained 6061 Al-Mg-Si Aluminum Alloy[D]. Zhenjiang:JiangsuUniversity,2016.
[10]葛灵丹,王树奇,杨子润. 7075铝合金的磨损行为及其机理探讨[J].特种铸造及有色合金,2011,31(2):178-182,205.Ge L D,Wang S Q,Yang Z R. Wear behavior and its mechanismof 7075 aluminum alloy[J]. Special-cast and Non-ferrous Alloys,2011,31(2):178-182,205.
[11]赵男男,刘群浩,吴俊,等.纯铝等径角挤压塑性流动的有限元模拟分析[J].材料与冶金学报,2015,14(4):263-268.Zhao N N,Liu Q H,Wu J,et al. The finite element simulation ofplastic flow in equal channel angular pressing for pure Al[J].Journal of Materials and Metallurgy,2015,14(4):263-268.
[12]张旭.纯铝等径角挤压有限元模拟及实验研究[D].沈阳:东北大学,2012.Zhang X. The Finite Element Simulation and Experimental Investi-gation in Equal Channel Angular Pressing for Pure Al[D]. Sheny-ang:Northeastern University,2012.
[13] Vinogradov A,Ishida T,Kitagawa K,et al. Effect of strain pathon structure and mechanical behavior of ultra-fine grain Cu–Cralloy produced by equal-channel angular pressing[J]. Acta Ma-terialia,2005,53(8):2181-2192.
[14]房大然.等通道转角挤压(ECAP)铝合金的力学性能和断裂行为[D].天津:天津大学,2007.Fang D R. Mechanical Properties and Fracture Behavior of Al Al-loys Subjected to Equal Channel Angular Pressing[D]. Tianjin:Tianjin University,2007.
[15] Ko Y G,Dong H S,Park K T,et al. An analysis of the strainhardening behavior of ultra-fine grain pure titanium[J]. ScriptaMaterialia,2006,54(10):1785-1789.