6xxx系铝合金导体材料的时效行为

综述了6xxx系铝合金导体材料的时效行为.微量元素Cu促进时效进程,减轻停放效应,提高峰值强度,Zr减缓时效进程,改善合金的耐热性,适量稀土对合金的性能产生好的影响.6xxx系铝合金导体材料的使用状态为β?相起主要强化作用的过时效状态.要开发出高电导率中强度铝合金导体材料,必须深入研究低Mg+ Si含量的Al-Mg-Si-RE铝合金时效行为.     

合金成分与热处理对6xxx系铝合金力学性能的影响

研究合金成分（Mg,Si,Cu）和热处理（自然时效和预时效）对6xxx系铝合金力学性能的影响。结果表明：合金成分与热处理不仅影响材料的成形性能,而且影响材料的烘烤硬化性能;提高合金中Si含量或Si／Mg比或添加0．3％Cu,可显著提高材料的韧性和成形性能,而预时效将减低材料的韧性和成形性能。对所研究合金的强度、韧性、加工硬化、应变敏感性、成形极限和烘烤硬化性进行了比较和总结。     

Effect of scandium on the hot extrudability of 7075 aluminum alloy

This study investigated the effect of the addition of scandium on the hot extrudability of 7075 alloys. Three kinds of Al-Zn-Mg-(Sc) alloys with up to 0.30 wt.% Sc were prepared, including 7075 aluminum alloy without Sc (AA7075). Differential scanning calorimetry (DSC) analyses and hot compression tests were conducted to examine the incipient melting temperature of the alloys produced. The addition of 0.30 wt.% Sc resulted in significant grain refinement and a fully equiaxed microstructure. Hot compression tests were conducted to determine the critical damage values based on Cockroft-Latham criterion. Then, the surface quality of an extruded bar of each alloy was simulated with a finite element code. The surface condition of an extruded bar was predicted and compared with the experimental results. After hot extrusion, AA7075 without the addition of Sc showed a more moderate surface quality than the alloys modified with Sc. However, AA7075 revealed coarse-grained bands just below the surface area. Extrusion limit diagrams were constructed for the three alloys.     

Simulation of the transformation of iron intermetallics during homogenization of 6xxx series extrudable aluminum alloys

A computational simulation of the β-AlFeSi to α-AlFeSi transformation has been performed in this work by integrating the process steps of solidification and homogenization. The composition profiles of alloying elements as well as the profiles of weight fractions of all solid phases computed after solidification were entered as input for the simulation of the homogenization process which involves the dissolution of the Mg₂Si and the transformation of β-AlFeSi to α-AlFeSi intermetallics.     

7xxx系铝合金时效处理研究的新进展

概述了7xxx 铝合金的时效处理的典型工艺,介绍了新的时效工艺--"双峰"时效工艺及其特点,探索了"双峰"时效工艺的普适性和双时效峰的强化机理以及应力腐蚀开裂(SCC)机理;结合自己的研究提出了"相变-Mg-H"复合理论,并用其解释了双时效峰的强化机理及应力腐蚀开裂(SCC)机理.针对目前研究工作的问题,提出了一些建议.     

采用近终形铸造制备高强6xxx铝合金控制臂

采用近终形铸锭配合热锻工艺制备高强6xxx铝合金控制臂。首先设计近终形铝合金锭坯的形状,采用Procast商业软件模拟研究近终形铝合金铸锭的铸造过程。结果表明,近终形铝合金铸锭的收缩行为与铸锭形状相关,经模拟计算优化后,铸造出无缺陷的近终形6xxx铝合金铸锭。为了获得优异的锻件性能,研究了6xxx铝合金的热压缩行为。结果表明,锻件组织中的亚晶百分数与Z参数值相关;中等Z参数（1．09×10^16MS^-1）有利于获得较高的亚晶百分数,从而保证锻件产品具有更优的性能。     

Strengthening-toughening of 7xxx series high strength aluminum alloys by heat treatment

1　INTRODUCTIONAerospaceand groundtransportationvehicleswithreducingstructuralmasscanenhancecarrycapa bilityandflexibility ,decreasefuelconsumption ,andextendflightvoyageevidently .Highstrengthstruc turalmaterialswithlightdensityplayapivotalroleonreducingmassinstructure .Presently ,confrontedwithcompetitionofresinbasedcomposites ,alu minumalloysas primarystructuralmaterialsforspacecraftandgroundtransportationvehiclesarede velopinginlinesofsuperhighstrength ,corrosionen durance ,lowdensitya…     

均匀化退火工艺对6060铝合金挤压材力学性能的影响

研究了不同均匀化退火制度对6060铝合金挤压型材性能的影响。通过对6060铝合金铸锭的金相显微组织和型材力学性能分析得出,在合适的均匀化退火制度下,可以有效消除6060铝合金铸锭组织的枝晶偏析和非平衡相的熔解,达到缩短均匀化时间,提高挤压速度、改善型材表面质量。     

The formation of streak defects on anodized aluminum extrusions

Streaking is a common surface defect on anodized extrusions of 6xxx series soft alloys. Very often, the defects only become apparent after anodizing, which makes it difficult to identify their root cause. In industry practice, a trial-and-error method has been taken to reduce the intensities of the streak defects, greatly increasing the fabrication cost. This paper describes the formation mechanism of various streak defects on the basis of a literature review and experimental results. This provides a basis for developing effective measures for preventing the formation of these defects for the extrusion industry.     

Improvement of formability of 6xxx aluminum alloys using incremental forming technology

Aluminum sheet is becoming increasingly common as an automotive body panel material. The heat-treatable aluminum alloys of the 6xxx series are widely used as an outer panel material, due to their ability to precipitation harden during the paint-bake cycle, resulting in improved dent resistance. Increasing the formability of these alloys would allow for multiple parts of less complex geometry to be combined into a single more complex part, thereby avoiding the costs associated with any subsequent joining operations. Incremental forming is a process that can improve material formability through the use of short, recovery heat treatments applied between increments of deformation. The objective of this study was to investigate the incremental forming behavior of 6111-T4 an alloy, which is often used for exterior body panel applications. Interrupted tensile testing was used to simulate the incremental forming process. The effect of different heat-treatment parameters on mechanical properties was analyzed. The heat treat regimen developed for uniaxial testing was then applied to a series of plane strain tests using a hemispherical punch, to simulate the more complex states of stress found in forming operations.     

对中国发展工业铝挤压材的探讨

在中国把挤压铝材按用途分为建筑及结构材（简称建筑材）与工业材（除建筑材以外的其他一切挤压铝材）。中国已跨过铝挤压强国门槛,自2001年成为挤压材净出口国以来,2005年的净出口量324．56kt。铝挤压工业的地区结构合理,与经济发展相适应;全球21个工业发达国家2004年的平均工业材与建筑材之比为54：46,没有一个国家工业材的比例达65％以上,中国2005年工业材的比例占34％,2012年的这个比例可达45％。截止到2006年底中国拥有16台大挤压机,总挤压力1170MN,总生产能力约140kt／a,但高速铁路与磁悬浮铁路车辆制造所需要的大挤压材仍不能满足需求,需要进口相当大的一部分。不是生产能力与产量不够,而是在品质方面存在诸多不尽人意之处。大挤压工业型材面临的最大挑战是市场与技术,是自主创新力量薄弱。中国还需要增建200MN与150MN的工业材挤压机各1台。     

铝合金型材拉弯有限元模拟

型材拉弯成形过程模拟属于高度非线性准静态问题,选择动力显示模块进行数值模拟时,需要考虑模拟分析步时间的敏感性。针对通用的型材拉弯工艺,在模拟分析步时间的敏感性分析基础上,采用ABAQUS/Explicit模块,建立了型材拉弯成形的准静态分析有限元模型。并采用ABAQUS/Standard模块分析预测回弹、侧壁厚度和截面畸变。为验证模拟方法的有效性,采用A-7B数控拉弯成形机完成2024-O铝合金Z型截面型材拉弯试验,测量试验件的回弹量、厚度和截面畸变情况。试验与模拟结果对比表明:补拉伸量对回弹量、厚度和截面畸变的影响趋势一致,其中,回弹量和厚度的平均相对误差分别为13.74%,1.66%。建立的模型能有效地应用于铝合金型材拉弯成形模拟。     

热处理对喷射成形7xxx系铝合金TIG焊接头组织与性能的影响

采用7055焊丝对喷射成形7xxx系铝合金进行TIG焊接,接头经450℃×1 h＋475℃×1 h的双级固溶后水淬,再进行120℃×24 h的时效处理后,焊缝组织均匀、晶粒有所长大,但没有出现过烧现象.经复合固溶处理后合金元素充分溶入基体,使得基体中的合金元素含量高于固溶前的含量,而固溶之前分布在晶界的合金元素经固溶之后降低了,固溶过程使合金成分区域趋于均匀化,后续的时效过程中过饱和固溶体析出强化相,使得接头强度得到了显著提高7,055达到了母材强度的65%,7475达到了母材强度的91%.结果表明,试验拟定的热处理工艺是合理的.     

Ca对Ma-Si合金显微组织和阻尼性能的影响

研究Ca对Mg-1 wt.%Si镁合金显微组织和阻尼性能的影响。结果表明,微量Ca可显著改善初生Mg2Si相的形貌,且可细化针状共晶相,Ca含量较高时,合金中有Ca MgSi相形成。Ca的加入可提高合金阻尼性能,降低临界应变振幅。不同Ca含量下合金阻尼特征均表现为应变振幅相关性,但在测试频率范围内,频率对合金阻尼性能影响不大。     

多级固溶处理对Al-5.8Zn-2.0Mg-2.0Cu合金挤压材组织与性能的影响

采用力学性能和电导率测定及剥落腐蚀、透射电镜组织观察等方法,研究了Al-5.8Zn-2.0Mg-2.0Cu合金挤压材固溶处理制度对最终组织和性能的影响。结果表明:在常规固溶处理基础上增加高温固溶处理的多级固溶处理制度,可以提高挤压材的力学性能,电导率有所降低,剥落腐蚀性能和纤维状分布的组织变化不大;此外,该合金挤压材中除分布有ZrAl3弥散质点外,还有较粗大的S相存在。     

铝合金振动焊接过程非线性时间序列模型分析

针对7系列超硬铝在传统熔焊过程中易出现热裂纹、气孔和焊接接头软化等问题,研究振动焊接工艺过程中,焊接工艺参数变化与焊接接头强度间的非线性关系机理,建立基于焊接过程工艺参数测量数据的7075超硬铝振动焊接接头强度非线性时间序列预测模型. 文中在7075超硬铝振动焊接过程参数测量数据的基础上,建立了焊接过程参数时间序列,并在此基础上研究建立了焊接过程系统相空间重构参数及确定性检验方法. 根据重构相空间的相点演化轨迹与焊接接头强度参数间的非线性关系,建立相空间相点演化轨迹的人工神经网络拟合模型,对焊接接头的断后伸长率、抗拉强度、硬度、焊缝余高、晶枝最大粗度、晶粒数量等物理参数进行计算. 根据建立的模型进行的一系列焊接接头强度试验显示. 结果表明,该模型的预测结果可以满足工程需要,具有工程实用价值.     

7075 铝合金强化固溶T76处理后的拉伸与剥落腐蚀性能

以2219-T87铝合金为塞棒材料,采用摩擦塞补焊工艺对8 mm厚7075-T651铝合金进行焊接,并对不同工艺参数下接头的成形、微观组织、力学性能等进行观察和测试.结果表明,采用优化的工艺参数可以获得无缺陷的接头,塞棒和母材摩擦界面形成了等轴晶.根据组织形貌可以把摩擦塞补焊接头分成再结晶区、热力影响区、塞棒热力影响区、热影响区、塞棒热影响区和母材6个区,热力影响区组织发生了变形和长大以及沉淀相的溶解和粗化,局部发生了软化,尤其是塞棒热力影响区硬度值最低,在90 ~ 95 HV左右,拉伸试验时无缺陷的接头断裂位置在塞棒区,断裂模式为韧性特征. 摩擦塞补焊接头抗拉强度最高可达343 MPa,断后伸长率最高达7.0%,分别达到母材的63.8%和77.8%.     

5A06铝合金MIG焊接工艺研究

采用脉冲MIG焊,通过对焊前准备、焊接方法、焊接材料、焊接规范等方面进行的试验和分析,确定了5A06-H112铝合金板(δ=5 mm)拼焊工艺规范结果表明,合理的焊接工艺规范能够有效控制焊缝的成形和焊接气孔的产生.     

SiC颗粒增强铝基复合材料的热挤压工艺研究

开展了ＳｉＣ颗粒增强铝基复合材料热挤压工艺的实验研究，分析了其挤压成形的力能变化规律。结果表明：该材料的挤压载荷随着变形温的提高而显著降低；在一定温度下，其挤压成形随着挤压位移的增加而呈出现填充挤压，强化挤压等阶段性变化的特点。