铝合金复合材料在汽车轻量化上的应用

推广汽车轻量化,加大铝质配件材料的应用,是我国汽车工业发展的当务之急,对解决我国能源短缺,道路超载、运输效率低下具有很重要的意义.加大铝质配件应用是汽车轻量化的措施之一,分析了汽车轻量化的铝合金材料结构性能,阐述了轻量化以铝为首的轻质材料在汽车上的应用措施,介绍了汽车工业的快速发展将给铝质散热器带来巨大的市场前景,论述了商用车采用铝合金车轮减轻车辆的自重显著,研究了国外汽车制造商大力研发车身轻量化技术,同时指出了轻质材料是汽车安全、节能、环保核心的技术优势和轻量化措施.     

汽车面板用铝合金的研究现状

铝合金以其高比强度,良好的成形性,优异的耐蚀性以及高的回收率成为汽车工业中减轻车重的理想轻质材料。表文介绍了国内外汽车面板用铝合金的研究现状及发展趋势。     

铝合金在车身外板上的应用

随着汽车行业的快速发展．近20年来,能源问题变得越来越突出。有关数据表明．汽车整车重量每降低10％,可节油6％～8％．排放降低4％。因此．减轻汽车自重、降低油耗成了各大汽车主机厂提高竞争力的关键。汽车轻量化主要有优化结构设计和采用轻质材料两种途径。由于铝具有密度小、耐腐蚀等特点．且铝合金塑性优良、强度高、有良好的回收性能,所以铝合金逐渐成为汽车制造的重要材料。汽车车身约占汽车总重的30％．仅在汽车车身覆盖件内外板上使用铝合金材料．便可使车身减重约40％～50％。     

铝板在车身覆盖件冲压生产中的关键技术

随着汽车轻量化的需求,铝合金材料被越来越多的应用到汽车制造领域。介绍了汽车行业常用2000系、5000系和6000系等铝合金材料,并简述了铝材料开发、在车身零件上的应用趋势,以及对于汽车轻量化的意义。从现场实际出发,通过对铝板材料的剪切、配送、存储、分张、冲压成形以及铝板零件的检修的各环节的现场分析,总结了四个方面的控制要点,即材料保存、板料拆垛、模具冲制、质检返修,并提出了预防材料发霉、解决铝板分张的措施、控制铝板成形质量以及铝板零件检验和返修要点等相应的解决方案。     

压铸铝合金及先进的压铸技术

综述了压铸铝合金的性能、优点汽车工业中的应用情况,简要介绍了合金元素在压铸铝合金中的作用以及世界各国所使用的压铸铝合金材料及其工艺。     

铝合金板材在汽车生产中的应用

铝合金是汽车轻量化的首选材料,越来越多应用于汽车覆盖件中.本文综述了汽车覆盖件用铝合金的种类及性能特点,介绍了国内外研究应用现状,并指出了其在国内生产应用中存在的问题,提出了研发方向.     

现代汽车板材的有铆钉塑性连接及其核心技术探讨

近些年,很多轻质材料如铝合金、镁合金等在现代汽车板材上得到了广泛应用。有铆钉塑性连接在轻质材料的连接上具有巨大优势。本文首先介绍了现代汽车板材有铆钉塑性连接方式及其机制,并对有铆钉塑性连接和点焊等连接方式进行了对比。分析了现代汽车板材有铆钉塑性连接的关键技术。有铆钉塑性连接的关键技术包括铆钉形状、塑性变形程度、板材表面状况、塑性变形速率和加热处理。     

汽车用铝合金的研究进展

介绍了铝合金在现代汽车工业中的应用,从合金元素、热处理工艺和冲压成形技术等方面分析了国内外汽车用铝合金的研究现状与发展趋势,指出铝合金是现代汽车工业最理想的材料之一。针对我国汽车用铝合金的开发与应用所存在的问题,提出了加速我国汽车用铝合金发展的建议和对策。     

铝合金在新能源汽车工业的应用现状及展望

汽车轻量化是全世界汽车工业的发展方向,而汽车轻量化的首选材料是铝合金。铝合金材料在汽车上的应用对解决我国能源短缺、环境污染、运输效率低下具有很重要的意义。分析了铝合金材料在新能源汽车轻量化中的应用,介绍了新能源汽车的快速发展将给铝合金材料的发展带来巨大的市场前景,指出铝合金等轻质材料的应用及新型结构设计是新能源汽车安全、节能、环保等核心的技术优势和主要的轻量化措施。     

Fe-Mn-Al-C系高Mn-Al轻质钢研究进展

Fe-Mn-Al-C系轻质钢以其低密度和高强韧性在车辆、交通运输、航空航天和发电厂等零部件的结构材料应用领域中受到广泛关注。基于当前Fe-Mn-Al-C系轻质钢的研究成果及其表现出的优异性能，综述了Fe-Mn-Al-C系高Mn-Al轻质钢在成分设计、显微组织特征和力学性能以及应用性能等方面的研究进展，重点阐述了轻质钢强韧化机制、力学性能和应用性能特点，并结合目前国内外学者对Fe-Mn-Al-C系高Mn-Al轻质钢的最新研究成果进行了展望。该系轻质钢的强韧化机制与析出相(MC型碳化物、κ-碳化物、B2和DO₃粒子等)的析出机理及其对轻质钢强韧化机制的影响机理和析出相对该系钢的氧化性、腐蚀性和耐磨性等各项应用性能的作用机制是今后该系轻质钢的重要研究方向。开展析出相可控析出研究有助于突破新一代钢铁材料增强增韧技术瓶颈，加快其实际应用。     

On the applicability of high strength self‐tapping aluminium bolts in magnesium nut materials for automotive applications

High strength aluminium bolts made of AW 6056 T6, AW 7075 T6 and T79 have been investigated regarding the applicability in magnesium nut materials for automotive applications. With respect to galvanic corrosion all combinations of aluminium bolts with magnesium parts show superior corrosion properties when compared to galvanised steel bolts connected to magnesium. With respect to stress corrosion cracking (SCC) no aluminium bolt in contact with magnesium failed due to SCC. This is because of cathodic protection of aluminium alloy through magnesium. Even peak‐tempered highest strengthened T6 7xxx aluminium bolts can be used for automotive applications when compressive residual stresses are present in the thread root of the bolts.     

Influence of time on residual stresses in friction stir welds in agehardenable 7xxx aluminium alloys

Friction stir welding (FSW) can be used to weld 7xxx series wrought aluminium alloys. As these materials are age-hardenable, their properties can change with time. This work used the neutron diffraction technique to measure the residual stresses around a FSW in a 7xxx alloy and to determine how these residual stresses changed with time. It was found that the residual stresses associated with the weld nugget decreased, while those associated with the heat-affected zone increased with time. This is in contrast to strength and hardness values that increased in all regions of the weld with time.     

7xxx系铝合金热处理的进展

7xxx系合金是基于Al-Zn-Mg（-Cu）系的可热处理的锻铝合金，广泛应用于高性能航空结构和运输部件。除了受成分、铸造和形变热处理影响外，材料性能的平衡明显受到其所经历的热处理方式的影响。描述了均匀化、固溶处理、淬火、时效对7xxx系高强合金组织和性能的影响。总结了在Monash大学进行的有关厚板产品的生产工艺，包括从均匀化到最终的时效处理，以及通过控制微观组织特征，比如弥散体、粗粒子、精细析出相、晶粒结构和晶界特征，来实现组织与性能的平衡。重点陈述了相关方法，如通过高温热处理溶解不需要的粗粒子、基于连续冷却析出行为的淬火敏感性变化、通过实验与建模来研究时效包括一步时效、两步时效、三步时效。对每种情况下的组织与性能都进行研究。     

Effect of Fe on Microstructure and Properties of 8xxx Aluminum Conductor Alloys

The effect of Fe contents (0.3-0.7 wt.%) on the microstructure, electrical conductivity, mechanical and creep properties of 8xxx aluminum conductor alloys was investigated. Results revealed that the as-cast microstructure of 8xxx alloys was consisted of equiaxed α-Al grains and secondary Fe-rich intermetallics distributed in the interdendritic region. The extruded microstructure showed partially recrystallized structure for 0.3% Fe alloy but only dynamically recovered structures for 0.5 and 0.7% Fe alloys. With increasing Fe contents, the ultimate tensile strength and yield strength were remarkably improved, while the electrical conductivity was slightly decreased. Moreover, the creep resistance was greatly improved, which is attributed to the larger volume fraction of fine intermetallic particles and smaller subgrain size in the higher Fe-containing alloys. The creep threshold stress was found to increase from 24.6 to 33.9 MPa with increasing Fe contents from 0.3 to 0.7%, respectively. The true stress exponent values were close to 3 for all three experimental alloys, indicating that the creep mechanism of 8xxx alloys was controlled by dislocation glide.     

Dispersoid precipitation and process modelling in zirconium containing commercial aluminium alloys

Small dispersoid particles inhibit recrystallisation and are thus critical in controlling the grain structure of many high strength commercial aluminium alloys. A general, physical model has been developed for the precipitation of Al₃Zr dispersoids in aluminium alloys. The predictions of the model have been compared with results of an experimental investigation of Al₃Zr precipitation in 7050. The model has been shown to faithfully reproduce the distribution of dispersoids observed in this alloy, correctly predicting dispersoid free zones observed in interdendritic regions and at grain boundaries. Furthermore, the predicted precipitation kinetics agree well with experimental observation. The model has been used to study the effects of homogenisation conditions and alloy composition on dispersoid formation and has been shown to be a powerful tool for optimising the dispersoid distribution in 7xxx series aluminium alloys.     

Controlling weld metal dilution for optimised weld performance in aluminium

Abstract

It is demonstrated how the current trend towards high speed, narrow groove welding, and the corresponding shift towards high base metal dilution, may result in decreased weldability for 6xxx and 7xxx aluminium alloys. In particular, variations in base metal dilution for extrusion alloys 6082 and 7108 have been examined for welds made with 5183, 5356, 5654, and 4043 filler alloys, particularly at high dilution ratios. The less common filler alloys 5039 and Safra 66 are also considered. Dilution curves superimposed upon existing hot cracking curves show that cracking susceptibility increases rapidly with base metal dilution for these alloys. Establishing an upper limit for dilution to avoid hot cracking, for a specific engineering application, also requires a knowledge of restraining conditions. For conditions of high restraint, i.e. rigid fixturing, enforcing an upper limit for base metal dilution will become critical. The effect of dilution on weld strength is also considered.     

Technology of braze welding absorber tubes to copper foil in solar collectors by the GTA method

The classification of aluminium alloys on the basis of main alloy elements and usability for heat treatment is presented. The essential problems occurring in welding of aluminium and its alloys are mentioned. The most advanced methods of joining these materials are described. Results of investigations into the possibility of joining of thin walled elements of aluminium alloys by low heat input arc welding methods, plasma arc welding and hybrid laser+MIG welding are also presented.     

不同时效态7050铝合金时效成形中析出相对应力松弛行为的影响

铝合金时效成形方法结合了合金的蠕变松弛和析出强化作用,作为一种先进的整体壁板制造技术倍受航空制造业青睐。7xxx系铝合金在时效成形过程中的应力松弛行为受到合金内析出相与位错蠕变交互作用的影响从而制约着成形后零件质量与性能。本文采用设计的应力松弛试验研究了不同时效态(固溶态,欠时效态和峰时效态)7050铝合金内析出相对时效成形过程中应力松弛行为的影响,并通过位错热激活动力学参数计算和显微组织表征分析析出相与位错运动的交互作用。结果表明时效成形过程中析出相对位错热激活运动有明显地阻碍作用,因此含有不同尺度析出相铝合金的应力松弛行为表现不同,随着析出相尺度的增加合金应力松弛速率减缓,应力松弛极限增大。不同时效态7050铝合金位错激活体积计算和显微组织表征结果都证明了应力松弛过程中析出相增大对位错运动的阻碍作用也越显著。峰时效态7050铝合金的位错激活体积最大,时效成形后塑性应变的转化率最低。此外,时效成形过程中,7050铝合金内析出相对位错热激活的阻碍作用引起了槛应力现象,且随着析出相的增大槛应力也逐渐增大。     

Strengthening of aluminium alloy 7005 through imposition of severe plastic deformation supplemented by different ageing treatments

Strengthening of aluminium alloys 7xxx through the imposition of severe plastic deformation supplemented by ageing treatments is a challenge due to the limited workability of these alloys in cold deformation regimes. This study aims to comprehensively investigate the strengthening of aluminium alloy 7005 through the imposition of severe plastic deformation supplemented by two different ageing treatments: pre-deformation artificial ageing or post- deformation natural ageing. For this purpose, microstructure evolutions of the alloy processed through mentioned procedures were studied using X-ray diffraction and scanning electron microscopy while the alloy strengthening was evaluated using Vickers hardness measurement. Results show that a superlative strengthening is obtained through the imposition of severe plastic deformation supplemented by post-deformation natural ageing. For instance, the yield strength of the alloy increases to more than 400 MPa, about one-third greater than the counterpart amount after the usual T6 treatment. This superlative strength mainly occurs due to refinement of grains, an increase of dislocation density and an increase of volume fraction of the precipitates that appeared during natural ageing. Considering the applied models, it is inferred that the increase of volume fraction of precipitates that appeared during natural ageing has a determinative role in the strengthening of the alloy.     

Modelling of 7050 aluminium alloy friction stir welding

Abstract

A thermal model combined with a microstructural and yield strength model has been developed to give a prediction of precipitate evolution and strength in the as welded and post-weld heat treated condition for friction stir welding of 7xxx aerospace aluminium alloys. This fully coupled model is applied to an overaged high strength 7050 aluminium alloy friction stir welded using a range of welding rotation and translation speeds. The evolution of the microstructure has been predicted as a function of the process parameters. The resulting microstructural evolution is shown to be a complex function of both peak temperature observed during the weld cycle and heating/cooling rates. Yield strength has been calculated from the microstructural predictions and a comparison between predicted yield strength and measured hardness has been used to test the modelling approach. Reasonably good agreement between model and experiment is found over the wide range of process parameters investigated.