6061铝合金加工技术在国内的研究进展

综述了6061铝合金加工技术研究的进展,主要包括6061铝合金的合金化、复合技术、表面处理、塑性加工、焊接工艺等方面,分析了6061铝合金加工技术研究存在的问题,并指出了6061铝合金加工技术研究的重点.     

7075高强铝合金构件冷成形强化机制研究

目的 针对7075高强铝合金构件在固溶-淬火-时效处理过程中成形精度低的问题,提出了7075高强铝合金预强化冷成形工艺,研究7075高强铝合金构件冷成形强化机制。方法 基于高强铝合金短流程高性能成形技术,经过固溶-时效处理,获得预强化处理的7075铝合金板料,使用预强化处理的7075铝合金板料冷成形试制帽形梁。通过拉伸试验、杯突试验测试预强化处理的7075铝合金板料及帽形梁力学性能,并通过透射电子显微镜试验解释7075高强铝合金构件冷成形强化机制。结果 预强化处理的7075铝合金板料抗拉强度为540 MPa,延伸率为19.3%,强度接近7075铝合金T6态强度水平,塑性接近7075铝合金O态塑性水平。杯突值为16.6 mm,达到7075铝合金O态的87%。使用预强化处理的7075铝合金板料冷成形试制的帽形梁表面质量良好,无破裂等情况。经过烤漆工艺后,帽形梁抗拉强度为(560±5)MPa,屈服强度为(480±5)MPa,与7075高强铝合金T6态强度相当。结论 预强化处理的7075铝合金板料基体内部存在大量GP Ⅱ区组织,这有助于提高7075高强铝合金的强度和塑性。使用预强化处理的7075铝合金板料冷成形试制的帽形梁在烤漆工艺处理时,基体中部分GP Ⅱ区会转变为η''相,析出相的转变和加工硬化的结合提高了成形构件的强度,使其强度可以达到7075高强铝合金T6态强度水平。     

LY12铝合金微观组织在交变磁场作用下组织变化研究

通过对LY12铝合金试件在交变磁场作用前后的微观组织变化研究,分析磁处理前后微观组织组成成份变化,进而得出交变磁场导致LY2铝合金组织细化的组织因素及作用机理,发现磁处理技术对铝合金的塑性有所提高,强度变化不人.     

Al-Zn-Mg-Cu系超高强铝合金的研究进展

评述了国内外超高强铝合金的研究及应用概况,介绍了Zn、Mg、Cu等主要元素与Zr、Sc、Li、Ag、Be及稀土等微量元素对Al-Zn-Mg-Cu系超高强铝合金组织与性能的影响,介绍了Al-Zn-Mg-Cu系合金制备技术、热处理工艺及其最新进展,讨论了超高强铝合金主要强化机制以及微观组织与性能之间的关系.针对超高强铝合金现存的问题,提出了今后研究开发的方向.     

不同热处理工艺对6061铝合金塑性和硬度的影响

不经过特殊处理的铝合金材料在常温条件下属于低塑性、难变形材料,制约其在工业中的应用.以6061-T6铝合金板材为研究对象,通过单向拉伸试验、维氏显微硬度测试和金相试验等方法分析了不同热处理温度、保温时间和冷却方式等热处理工艺参数对6061铝合金塑性性能和硬度的影响规律.研究结果表明,再结晶发生的程度是影响6061铝合金塑性性能的主要原因.热处理加热温度在410～590℃范围内,保温时间为2 h,采用空冷(AC)冷却条件,6061铝合金的塑性性能随热处理温度的升高呈现出波动增加,在560℃时达到最大值22.92％;而其硬度则表现出先降后升的变化趋势.在同一热处理温度和冷却方式条件下,延长保温时间,6061铝合金的塑性性能先增大后减小,总体呈上升趋势,而硬度则先降后升.在同一热处理温度和保温时间条件下,空冷(AC)、炉冷(FC)和水冷(WQ)三种不同的冷却方式对6061铝合金塑性性能的影响不大,但对其硬度的影响较大.在所选试验条件下,综合考虑6061铝合金的力学性能指标,热处理加热温度为560℃、保温时间为4 h、水冷方式下能够获得较为理想的强度、硬度和塑性性能.     

热处理参数对铝合金塑性成形性能分析

目的 研究温度升高对铝合金塑性成形性能的影响,分析高温条件下铝合金塑性成形性能.方法 搭建铝合金试样试验装置并控制相应温度,对铝合金进行单向拉伸试验和金相试验,记录铝合金的变形温度,分析其塑性成形性能.采集铝合金试验数据后,引用Zener–Hollomon参数模型,设置试验流程以及参数,设置不同数值的高温条件.结果 当...     

铝镁合金焊丝的研究现状

随着交通运输工具的轻量化和高速化,铝合金得到广泛应用,同时,对铝合金的焊接技术与焊接材料提出了更高的要求.铝镁合金具有良好的塑性断裂韧度、疲劳强度和耐蚀性,同时还具有良好的成形工艺性和焊接性,因此成为铝合金的主要焊接材料.重点介绍铝镁合金焊丝的成分、性能与生产工艺的研究现状,提出其存在的问题及发展趋势.     

快速凝固7000系超高强铝合金的研究现状

在对传统7000系高强铝合金分析的基础上,着重阐述了快速凝固超高强铝合金的发展过程、存在问题和研究现状.快速凝固技术可有效细化组织、提高合金元素的极限固溶度、抑制宏观和微观偏析,并提高超高强铝合金的综合性能,最后提出了快凝超高强铝合金的应用和发展前景.     

铝合金超塑变形研究进展

综述了铝合金材料超塑变形的研究现状和进展情况.着重介绍了高应变速率下铝合金超塑性的基本特征,探讨了铝合金超塑变形机理,介绍了铝合金超塑性的应用情况.超塑铝合金是性能优良,具有广泛用途的新型材料,随着高应变速率条件下铝合金超塑变形研究的深入,将不断提高铝合金生产的经济效益和实用性.     

车身制造中的铝合金板热处理-冲压一体化技术

随着能源和环境问题日益严峻,对汽车轻量化的需求愈发强烈,高比强度铝合金板在车身中的应用成为重要发展方向.铝合金板在室温下较低的成形性促使人们将各种成形技术引入到汽车制造领域.本文简述了适用于铝合金板件小批量生产的超塑性成形和板材液压成形等特种成形技术,重点介绍了适用于铝合金构件大批量生产的热处理-冲压一体化技术,包括带中间退火-冲压一体化技术、温冲压、W态下冲压和热冲压,阐明了它们的发展历史和现状,指出铝合金板热处理-冲压一体化技术控形控性的关键,最后比较了不同技术的优缺点,并展望了铝合金板冲压技术未来应重点开展的工作.     

大塑性变形制备超细晶/纳米晶Al-Mg铝合金的研究进展

近年来,大塑性变形(SPD)制备具有先进结构和功能的超细晶和纳米晶Al-Mg铝合金的研究取得了很大进展。SPD后,合金的晶粒显著细化、位错密度提高及有非平衡晶界和晶界偏析形成,这些微观结构导致合金的强度、硬度大幅提高。然而,SPD合金的塑性普遍较低。综述了SPD制备的Al-Mg铝合金在结构和性能方面的一些最新研究成果。     

应用等通道转角挤压(ECAP)技术制备超细晶钛合金

等通道转角挤压(equal channel angular pressing,ECAP)是一种强塑性变形技术,能有效细化材料的微观组织,提高材料性能,改善难变形材料的成形性.简述了ECAP技术制备超细晶钛合金的原理和技术现状,分析了不同工艺参数对钛合金ECAP变形过程和材料性能的影响以及晶粒细化的微观机制.     

Simultaneous increase in the strength,plasticity, and corrosion resistance of an ultrafine-grained Ti–4Al–2V pseudo-alpha-titanium alloy

The influence of severe plastic deformation on the structural-phase state of grain boundaries in a Ti–4Al–2V (commercial PT3V grade) pseudo-alpha-titanium alloy has been studied. It is established that increase in the strength, plasticity, and corrosion resistance of this alloy is related to the formation of an ultrafine- grained structure. In particular, it is shown that an increase in the resistance to hot-salt intergranular corrosion is due to diffusion-controlled redistribution of aluminum and vanadium atoms at the grain boundaries of titanium formed during thermal severe plastic deformation.     

In vitro fibroblast response to ultra fine grained titanium produced by a severe plastic deformation process

The in vitro response of the mouse fibroblast cell line 3T3 on the surface of ultrafine grained titanium [produced by a severe plastic deformation (SPD) process] has been studied in this work. SPD Ti showed much higher strength than the coarse grained Ti and equivalent to that of Ti–6Al–4V alloy. Better cell proliferation was observed on SPD Ti compared to conventional Ti and Ti–6Al–4V alloy. This could be attributed to the increased surface free energy by reduction in the grain size and possibly the presence of a large number of nano size grooves at the triple point junctions in SPD Ti sample. There was no significant difference in the results of cytotoxicity tests of fine and coarse grained materials.     

Atomic-scale dissecting the formation mechanism of gradient nanostructured layer on Mg alloy processed by a novel high-speed machining technique

Severe plastic deformation(SPD)-induced gradient nanostructured(GNS)metallic materials exhibit supe-rior mechanical performance,especially the high strength and good ductility.In this study,a novel high-speed machining SPD technique,namely single point diamond turning(SPDT),was developed to produce effectively the GNS layer on the hexagonal close-packed(HCP)structural Mg alloy.The high-resolution transmission electron microscopy observations and atomistic molecular dynamics sim-ulations were mainly performed to atomic-scale dissect the grain refinement process and corresponding plastic deformation mechanisms of the GNS layer.It was found that the grain refinement process for the formation of the GNS Mg alloy layer consists of elongated coarse grains,lamellar fine grains with deformation-induced-tension twins and contraction twins,ultrafine grains,and nanograins with the grain size of～70 nm along the direction from the inner matrix to surface.Specifically,experiment results and atomistic simulations reveal that these deformation twins are formed by gliding twinning partial dis-locations that are dissociated from the lattice dislocations piled up at grain boundaries.The corresponding deformation mechanisms were evidenced to transit from the deformation twinning to dislocation slip when the grain size was below 2.45 μm.Moreover,the Hall-Petch relationship plot and the surface equivalent stress along the gradient direction estimated by finite element analysis for the SPDT process were incorporated to quantitatively elucidate the transition of deformation mechanisms during the grain refinement process.Our findings have implications for the development of the facile SPD technique to construct high strength-ductility heterogeneous GNS metals,especially for the HCP metals.     

The processing of ultrafine-grained materials through the application of severe plastic deformation

The application of severe plastic deformation (SPD) to bulk metals provides the opportunity of achieving grain sizes in the submicrometer and nanometer range. Several different SPD processing techniques are now available including Equal-Channel Angular Pressing (ECAP), High-Pressure Torsion (HPT) and Accumulative Roll-Bonding (ARB). This paper examines the principles of grain refinement using ECAP and gives examples of the advantageous properties that may be achieved including increased strength at ambient temperatures and a superplastic forming capability at elevated temperatures. Invited paper presented in Symposium C at 5th Brazilian MRS Meeting, Florianópolis, Brazil.     

Shear deformation and grain refinement during accumulative back extrusion of AZ31 magnesium alloy

The accumulative back extrusion (ABE), as a new-noble severe plastic deformation (SPD) technique, has been employed to clarify the microstructural evolutions of AZ31 magnesium alloy during severe deformation. The latter has been explored using a 3D finite element analysis along with the microstructural investigations. The distribution of ABE generated shear strain (SS) and its corresponding microstructures have been thoroughly studied. The results indicated that the restrictions of material flow during ABE processing had been led to the mechanical shear bands generation in the microstructure. In addition, the occurrence of continuous dynamic recrystallization (CDRX) within the bands has resulted in a local grain refinement in those areas. Consequently a bimodal structure including the fine recrystallized grains along with the elongated ones has been developed. The effect of deformation mode on the microstructural refinement has been also discussed through considering the developed SS history and the related microstructural refinement.     

Fatigue of Severely Deformed Metals

In this brief communication, we would like to review present data on fatigue performance of ultra‐fine grain materials fabricated by severe plastic deformation (SPD) and to discuss the possible mechanisms of their plastic deformation and degradation in light of currently available experimental data. The most prominent effect of SPD is often associated with significant grain refinement down to the nanoscopic scale. The other evident effect, which accompanies intensive plastic straining, is the dislocation accumulation up to limiting densities of 10¹⁶ m^–2. Since namely these two factors, the grain size and the dislocation density, govern the strengthening of polycrystalline materials, we shall primarily confine ourselves to their role in cyclic deformation of severely pre‐deformed metals.     

纳米和超细晶金属材料的退火强化

本文综述了纳米和超细晶金属材料的退火强化研究现状和发展趋势。本文关注致密纳米和超细晶材料的研究,首先介绍了电沉积纳米Ni、强塑性变形制得的超细晶金属钛和纯铝的退火强化的实验现象,随后综述了这一强化现象的微观机理,最后探讨了进一步的实验及理论分析的途径。     

Microstructure and properties of magnesium alloy processed by a new severe plastic deformation method

A new severe plastic deformation (SPD) method called C shape equal channel reciprocating extrusion (CECRE) was developed to fabricate fine grained AZ31 Mg alloys. The results show that homogeneous microstructure with mean grain size of 3.6 μm is obtained as the accumulated true strain is increased to 11. Strain localization leading to dynamic recrystallizaion (DRX) occurring is the main reason for grain refinement during CECRE process. At the same time, the hardness of AZ31 alloy increases from 62.6 of as-extruded to 74.6 of CECRE 4 passes.