铝含量对AS系列铸造镁合金机械加工性能的影响(英文)

研究铝含量对AS系列铸造镁合金机械加工性能的影响。通过测量切削力和表面粗糙度对镁合金的机械加工性能进行评估。研究合金的微观结构和拉伸性能。结果表明,切削力随着铝含量的增加而增大;AS91镁合金的表面粗糙度和力学性能最高;对力学性能有影响的主要机制是存在金属间相Mg2Si和Mg17Al12。在机械加工镁合金中,切削力随着切割速度的增大而增大。所测得的数据与机械加工合金的力学性能一致。     

铝含量对AZ系列镁合金机械加工性能的影响

研究铝含量对AZ系列铸造铝合金机械加工性能的影响。为评价该合金的机械加工性能,测量切削操作过程中的切削力以及表面粗糙度,以及研究显微组织和拉伸性能。结果表明：添加2%铝含量的镁合金具有最佳的拉伸性能。随着铝含量增加到2%以上,由于晶界上析出金属间化合物β-Mg17Al12,切削力会随延展性的降低而降低。切削力也会随着切削速度的增加而增大,这是由于在加工过程中切削工具的尖端有侧面生成。     

固溶热处理对AA7085铝合金组织与性能的影响

采用拉伸试验、电导率测试、剥落腐蚀试验、金相观察及透射电镜分析等方法,研究了不同固溶热处理工艺(包括常规固溶、高温预析出固溶与部分重固溶)对AA7085铝合金的强度、剥落腐蚀性能及显微组织的影响。结果表明,采用部分重固溶工艺并时效处理后,合金的抗拉强度降低,但电导率与抗剥落腐蚀性能明显得到提高。其原因是通过部分重固溶处理并时效处理后,合金中的晶界析出细小且非连续分布的η析出相,从而提高了AA7085铝合金的抗腐蚀性能。     

Effects of Fe intermetallics on the machinability of heat-treated Al–(7–11)% Si alloys

The need for bridging the divide between the casting process and the machining process provides a strong motivation for examining the various aspects affecting the machinability of Al–Si casting alloys, given that these alloys constitute about 85% of all aluminum castings produced. Strontium-modified, grain-refined, T6 heat-treated 396 alloys (containing ～11% Si), and B319.2 and A356.2 alloys (containing ～7% Si) were selected, with a view to studying their machinability characteristics. Three 396 alloy compositions were selected (M1, M3, M4) such that different iron intermetallic phases were obtained in each case. Drilling and tapping operations were both carried out using a Makino A88E machine under fixed machining conditions. The machinability criteria relates to forces and moment analysis as well as to tool life, chip configuration, and built-up edge (BUE) evolution. The effects of Fe-intermetallics (α-Fe, β-Fe, and sludge) on the machining characteristics of these alloys were investigated and a comparison was made between the three 396 alloys in terms of mean total drilling forces, mean total tapping forces, tool life, and chip configuration. The results demonstrate that the presence of sludge has a significant effect on cutting forces and tool life. The tool life of the 396-M3 alloy (containing sludge) decreased by 50% compared to the base alloy 396-M1 (containing α-Fe intermetallics). Increasing the Fe-content from 0.5% to 1% in the M1 alloy (i.e., M4 alloy) produces a distinct improvement in the alloy machinability in terms of cutting forces and tool life. The addition of Fe and Mn appears to have no discernible effect on the built-up-edge (BUE) width and chip configuration as compared to the base alloy. The dominant type of wear which leads to drill failure and breakage is outer corner wear; there is, however, no evidence of crater-wear. Fan-shaped chips were obtained during machining of the 396, B319.2 and A356.2 alloys, where the latter alloy yielded the largest chips. As far as the alloy Si content was concerned, it was found that the 396 alloys produce drilling results similar to those of the B319.2 and A356.2 alloys, in terms of the number of holes drilled (cf. 2160 with 2100 and 2285 holes drilled in the B319.2, and A356.2 alloys, respectively). During tapping tests, however, the B319.2 alloy yielded the longest tool life, i.e., more than twice that of 396 alloy and four-and-half-times that of the A356.2 alloy.     

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.     

Cu／Mg比对AA7085显微组织与性能影响

采用熔铸法制备具有不同Cu／MgLk（0．67,1．0,1．06,1．6）的AA7085铝合金。采用金相显微镜、扫描电镜、力学性能测试和腐蚀测试研究Cu／Mg比对基体合金显微组织、力学性能和腐蚀行为的影响。结果表明,当Cu／Mg比为1．6时,AA7085铝合金具有更好的抑制再结晶能力和抗腐蚀性能。当Cu／Mg比为0．67时,铝合金具有更为优越的力学性能,其抗拉强度与屈服强度分别达到586和550MPa。而当Cu／Mg比为1．0时,合金的力学性能和耐腐蚀性能均下降。     

时效析出相微结构改变对AA2024铝合金应力腐蚀行为的影响

通过恒载荷应力腐蚀实验、扫描电镜（SEM）和透射电镜（TEM）等测试方法,研究了时效处理中析出行为的变化对AA2024铝合金应力腐蚀行为的影响。结果表明,合金在T3态时对应力腐蚀较为敏感,进行T8时效处理后,合金的应力腐蚀敏感性显著降低。利用高角环形暗场成像扫描透射电镜技术（HAADF-STEM）对合金进行准原位腐蚀实验观察,研究了合金T3和T8时效状态下的腐蚀过程和析出行为的变化情况,直观地展示了不同时效状态合金的腐蚀形态：T3态的合金为晶间腐蚀形貌,T8态的合金为晶间腐蚀和晶粒腐蚀相结合。由于析出行为和腐蚀机制的改变,不同时效状态的AA2024铝合金的应力腐蚀敏感性不同。     

异种搅拌摩擦焊AA5083-H111和AA6351-T6铝合金的力学和冶金性能(英文)

研究异种搅拌摩擦焊AA5083-H111和AA6351-T6铝合金的微观结构和力学性能。在3种不同的焊接速度(36、63、90 mm/min)下焊接AA5083-H111和AA6351-T6铝合金,分析焊接速度对接头力学和冶金性能的影响。结构表明,与其他焊接速度相比,焊接速度为63 mm/min时接头的力学性能和冶金性能较好。焊缝区由未混合区、机械混合区和混流区组成。所观察到的断裂模式为韧性纤维断裂。     

工业牌号铝合金的超塑性能及微观组织演化特征

采用实验方法研究国外广泛用于汽车车身板件冷冲压成形的工业牌号铝合金板材AA5182和6016的超塑性能,以及超塑变形中微观组织的演化特征。通过超塑性单向拉伸试验、材料变形前后的微观组织观察和自由胀形试验,揭示出铝合金AA5182具有一定的超塑性能,而铝合金6016的超塑性能很低。铝合金AA5182在温度为375℃、应变速率为1.67×10-3/s时,材料的延伸率达到210%,m值达到0.25;在温度为500℃、应变速率为1.67×10-2/s时,材料延伸率达到225%,m值达到0.35。     

Effect of semi-solid forming on the microstructure and mechanical properties of the iron containing Al-Si alloys

Iron is the most common impurity in aluminum casting alloys. The iron-bearing intermetallic compounds have the detrimental effects on the mechanical properties of the alloys. The aim of this research is to study the effects of plastic deformation and semi-solid forming on the morphology and distribution of the iron-bearing intermetallics and the microstructure and mechanical properties of the Al-Si alloys. Different amounts of iron and manganese were introduced into the A380 aluminum casting alloys. The alloys were processed through plastic deformation, recrystallisation and partial melting (RAP), and thixoforming. The microstructure and mechanical properties of the thixoformed alloys were investigated. The results showed that the RAP and thixoforming processes promote the formation of the very fine and well-distributed α-Al₁₅(FeMn)₃Si₂ compounds in the aluminum matrix. The yield and tensile strength as well as elongation of the alloys have been increased considerably by semi-solid forming compared with the as-cast condition.     

Investigation of the Friction Stir Lap Welding of Aluminum Alloys AA 5182 and AA 6022

Friction stir lap welding of the similar and dissimilar aluminum alloys is investigated. AA 5182 and AA 6022 aluminum alloys (the widely used aluminum alloys for automobile applications) are selected for the feasibility studies. The friction stir lap welding shows that the placement of the aluminum alloys in the different orders over each other affect the final weld quality and its mechanical properties. The welding parameters such as rotational and traverse speeds and the penetration depth are key factors to affect the micro-structure soundness. The mechanical and the micro-structural characterization is performed on the joints formed with varying welding parameters and from the different order of placement of the AA 6022 and the AA 5182 sheets. The weld failure occurs on the advancing side during the peel tests indicating that the retreating side is relatively stronger. Measured temperatures indicate that the advancing side has higher developed temperature during the course of welding compared to the retreating side.     

Cr和Zn元素对AA3xxx合金均质化热处理微观组织演化的模拟研究

Cr和Zn作为杂质或添加合金元素对铝合金产品的最终性能有很大影响。采用基于热力学与扩散动力学的KWN模型，研究了这两种元素对AA3xxx合金均质化热处理过程中弥散相形成的影响。该研究的目的是展示数学模型对铝合会成分及工艺设计的指导作用。     

Extrusion of silicon-rich AlMgSi alloys

As a part of on-going research on phase transformations during the deformation of light alloys, the effect of silicon excess on the extrudability and mechanical properties of the standard AlMgSi1 alloy within AA6082 alloy is investigated in this study. The AlMgSi1 alloy and three experimental aluminum alloys with a silicon content of 1.98%, 3.73% and 5.51% were direct-chilled cast into billets 95 mm in diameter, homogenized at 540 °C for 4 h and extruded into 12 mm diameter rods at different extrusion speeds. The results showed that an increase in the silicon content reduced the extrudability of the AlMgSi1 alloy by lowering the limiting extrusion speed. However, the extruded alloys with 3.73% and 5.51% silicon, generally characterized by a fine grained microstructure, exhibited higher strength levels compared with the 1.98% silicon alloy. Nonetheless, the mechanical properties of these alloys, in the T6 temper condition, were below those of the AlMgSi1 base alloy.     

Tailored heat treated accumulative roll bonded aluminum blanks: failure under bending stresses

Ultrafine-grained accumulative roll bonded (ARB) sheet metals of aluminum alloys have a high potential for lightweight construction. The mechanical properties can be enhanced regarding strength and ductility by the combination of ARB and a local heat treatment according to the Tailor Heat Treated Blanks technology. The present investigation focuses on the failure behavior of ultrafine-grained ARB blanks. Due to the low formability of these high-strength ARB metals, a detailed understanding of the failure mechanisms is essential. For this purpose, an established approach to determine the different stages of damage of the material for conventional materials is now applied to multilayered aluminum in the as-received and heat-treated condition. In this context, air bending tests are used to qualify and quantify the bending and forming behavior of ARB sheets of AA1050A and AA6016 aluminum alloys.     

Study of the potential electrochemical noise during corrosion process of aluminum alloys 2024, 7075 and pure aluminum

Properties of the potential electrochemical noises (EN) generated during the corrosion process of aluminum alloys AA2024(T3), AA7075 (aged at 121°C/35 h + 160°C/20 h) and pure aluminum in 3wt% (mass fraction) NaCl solution were investigated in this study. During the initial stage of immersion, the EN amplitude of AA2024 is the largest while the EN amplitude of pure aluminum is negligible. The amplitude of the EN generated by these materials decreases with immersion time except the EN of AA2024 after extremely long immersion time (38 days in this study). Surface morphology corresponding to different stages of immersion and different types of EN were studied by scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) analysis. The result shows that the micro‐galvanic cells formed by the constituent particles and the alloy matrix play an important role on the corrosion process of the aluminum alloys and the EN behaviors of AA2024, AA7075 and pure aluminum is proved to be strongly related to the type and intensity of corrosion process.     

多级热处理工艺对铝合金AA7049性能的影响(英文)

T6态高强7xxx系列铝合金对应力腐蚀开裂敏感。采用回归和再时效热处理(RRA)可以提高其抗应力腐蚀开裂性能而不降低其强度性能。研究了多级热处理工艺对7049铝合金性能和组织的影响。通过电导率测量、DSC分析和TEM组织观察,考察合金在不同热处理态的组织变化。DSC分析表明,RRA处理会导致合金的显微组织发生显著变化,RRA处理态合金的组织与T6和T73态合金的组织明显不同。RRA处理可以使合金保持在T6态的强度且获得T73态的热力学稳定性能。     

Research of Tribological Behaviors of a New Aluminum Bronze

ALUMINUM BRONZE is an important engineeringmetal.It has been widely used to manufacture parts thatrequire high wear resistance and high stress based onsome important properties,such as high strength,certain ductility,excellent wear resistance andcorrosion resistance,etc.Typical applications includemarine propeller,valves,mould,gear blanks and so on.In recent years,tribological behaviors of aluminumbronze have been intensively investigated.For example,some researches were focused on the e…     

Influences of Nickel and Vanadium Impurities on Microstructure of Aluminum Alloys

In recent years, the deterioration in the available coke quality for anode production has led to increased levels of metal impurities such as nickel and vanadium in primary aluminum. There is growing concern from the industry with regard to the impact of increased Ni and V levels on the downstream properties of Al alloy products. This article presents a detailed investigation of the influences of Ni and V impurities on microstructure of three common Al alloys, i.e., AA6063, AA3102, and A356, in both as-cast and heat-treated conditions. The characterization techniques employed include scanning electron microscopy, electron backscattered diffraction, energy-dispersive x-ray spectroscopy, wavelength-dispersive spectroscopy, and transmission electron microscopy. It is shown that the phase constituents of AA6063 are not altered by Ni additions up to 0.05% or V additions up to 0.04%. Whereas there is no change in phase constituents with increasing Ni up to 0.015% for AA3102, the addition of 0.05% Ni seems to have significant influence on the microstructure. For A356, Ni additions up to 0.02% do not seem to have significant influence on the microstructure, but a new phase with significantly high Ni content is formed when the Ni impurity level is increased to 0.05%. The deep insight obtained in this work should be helpful to understand the influences of Ni and V impurities on properties of Al alloys.     

Definition of quality in cast aluminum alloys and its characterization with appropriate indices

In this paper, the issue of “quality” of cast aluminum alloys from various viewpoints is interpreted. Many methods to characterize the quality of materials are available; the methods used currently for the quality evaluation of cast aluminum alloys include nondestructive testing, characterization of the microstructure, and mechanical testing. With regard to mechanical testing, a number of quality indices have been devised to evaluate and characterize the quality of cast aluminum alloys. As these quality indices use different mechanical properties for the quality evaluation, they are expected to lead to different results. In this work, the application of proposed quality indices and their suitability is discussed for a number of situations, including minor variations in chemical composition, different solidification rate, solid solution and artificial aging heat treatments.     

The effect of oxygen in resulfurized steels—Part II

Part I of this two-part paper, which appeared in the June issue, covered the effects of deoxidation with silicon, boron, aluminum, or carbon (under vacuum) on the machinability and microstructure of low-carbon resulfurized steels containing nominally 0.1%C-1.0%Mn-0.25%S. Deoxidation reduced machinability and it was concluded that the removal of oxygen was directly responsible. Deoxidation was found to suppress the formation of large random sulfide inclusions so that sufficiently strong deoxidation, such as with aluminum, caused the steel to solidify with a characteristic eutectic structure in which the inter dendritic sulfide inclusions were comparatively small. Consequently, the inclusions in the rolled steel were small and machinability was reduced.