Effect of Sc on Al_(3)Fe phase and mechanical properties of as-cast AA5052 aluminum alloy

The AA5052 aluminum alloy is widely used in automobile and aerospace manufacturing,and with the development of light-weight alloys,it is required that these materials exhibit better mechanical properties.Previous studies have demonstrated that the addition of Sc to aluminum alloys can improve both the microstructure and properties of the alloys.In this study,the effect of Sc on the Fe-rich phase and properties of the AA5052 aluminum alloy was studied by adding 0%,0.05%,0.2%,and 0.3%Sc.The results show that with the increase of Sc,the coarse needle-like Fe-rich phase gradually transforms into Chinese-script and then nearly spherical particles,reduce the size of Fe-rich phase,and refine the grain with increase of high angle grain boundaries(HAGBs).These microstructure changes enhance the strength of the AA5052 alloy through Sc addition.The ductility of the alloy is obviously improved because the addition of a lower amount of Sc changes the morphology of Fe-rich phase from needle-like into a Chinese-script,and it is subsequently reduced as a result of significant increase in HAGBs with increasing Sc content.

单体种类对光固化增材制造5052铝合金的影响

针对光固化增材制造5052铝合金时存在的浆料不稳定、烧结体密度偏低和碳残留量较高等问题,研究了树脂单体种类对铝合金光固化增材制造的影响。结果表明,单体种类对光固化增材制造5052铝合金的成型工艺和烧结体性能具有重要影响。采用单体TMPTA或PEG400DA的铝浆黏度大于30 Pa·s,沉降时间大于120 h,成型的铝合金坯体结构完整但表面孔洞较多;采用单体PEG200DA或HDDA的铝浆黏度低于30 Pa·s,但沉降时间小于16 h,成型的铝合金坯体表面无孔洞但结构易残缺;采用单体PS-PCL的铝浆黏度低于30 Pa·s且稳定不易沉降,坯体表面无孔洞且结构完整。采用优选单体PS-PCL制备固含量55%铝浆,打印成型并烧结后,其相对密度大于95%,碳残留量相对较低(0.259 17%),断口烧结颈明显,硬度相对较高(29.94HV)。

5052铝合金成形极限预测及数值模拟

基于Nakazima半球凸模胀形实验,利用有限元软件建立其简化模型。分析了润滑条件、冲压速度和凹模圆角半径对5052铝合金成形极限的影响。结果显示:随着摩擦因数的增大,成形极限曲线(FLC)向下偏移,表明理想的润滑条件有利于板材在复杂工艺下的成形;增大冲压速度也使FLC呈现下降的趋势,即在不考虑实际生产效率的情况下,降低冲压速度可以改善材料的延展性;而增大凹模圆角半径使FLC向上偏移,提高了板料的成形极限。将模拟结果与实验结果对比,两者较高的吻合度验证了有限元预测的可靠性。

石墨烯添加量对5052铝合金力学性能的影响

以5052铝合金为基体,采用搅拌摩擦加工制备复合材料,研究了不同石墨烯添加量对复合材料中石墨烯的分散与复合材料力学性能的影响。结果表明,当石墨烯添加量不超过1.0wt%时,复合材料中石墨烯可实现较好地分散;随石墨烯添加量的提高,复合材料的显微硬度呈上升的趋势,当石墨烯添加量为2.0wt%时,复合材料的平均显微硬度为87.44 HV,较同等条件基体的显微硬度提高了64.3%;复合材料的强度呈先升后降的趋势,当石墨烯添加量为1.5wt%时,复合材料的屈服强度与抗拉强度分别为139.0 MPa和247.5 MPa,相比同等条件基体的屈服强度与抗拉强度分别提高了63.1%和24.5%。

多道次拉伸和感应电流处理5052铝合金的力学性能和显微组织演变

提出一种多道次拉伸和感应电流处理(IEPT)相结合的复合成形方法,采用TEM和EBSD揭示感应电流对材料显微组织和力学性能的影响规律。结果表明,采用4次拉伸5%和拉伸后放电,材料伸长率比原始材料增加145%。预拉伸试样经过IEPT处理后,强度下降、塑性提高,材料的位错密度下降,晶粒变形结构向亚结构转变,同时晶粒尺寸略有增加。感应电流减弱材料的各向异性,出现新的<111>//TD织构。电塑性效应和焦耳热效应的结合增强位错运动和空位移动。采用ANSYS软件模拟板料的温度分布,最高温度达到144.7℃。材料强度的理论计算结果与实验数据一致。

自阻加热温度对5052铝合金板力学性能和组织的影响

通过扫描电镜、显微硬度、自阻加热拉伸实验等方法对自阻加热温度对5052铝合金板力学性能、组织和断口形貌的影响规律进行研究。结果表明,在25℃时5052铝合金板的抗拉强度、显微硬度、强塑积、变形抗力均最大,伸长率最小,随着自阻加热温度的逐渐升高,抗拉强度、显微硬度、强塑积、变形抗力均变小,伸长率变大。在350℃时伸长率为26%,抗拉强度为87 MPa。断口形貌有明显的韧窝,自阻加热温度从200℃到350℃,在断口表面有少许熔断的痕迹。随着温度的升高,韧性断裂明显,200~300℃时韧窝数量逐渐增多,韧窝深度增大,塑性提高。随着自阻加热温度的逐渐升高,5052铝合金组织中的β相熔入基体增加,β相减少,β相分布越来越均匀,纤维组织逐渐减少,塑性提高。

6061/5052异种铝合金钨极惰性气体保护焊接头的组织与性能

制备了6061/5052异种铝合金钨极惰性气体保护焊(TIG)接头,研究了接头的显微组织、晶粒尺寸、硬度、抗应力腐蚀性能和预腐蚀疲劳性能。结果表明:6061铝合金母材,焊缝和5052铝合金母材的平均晶粒尺寸分别为38.42,47.13,41.17µm;母材区显微硬度高于热影响区和焊缝区,硬度最小值(51 HV)出现在6061铝合金侧热影响区;接头在NaCl溶液和空气中应力腐蚀后,断裂位置均在6061铝合金侧距焊缝中心14 mm处,在NaCl溶液中的抗拉强度、屈服强度和断后伸长率略高于在空气中,抗应力腐蚀性能略强;随着NaCl溶液中HCl含量增加,焊接接头的晶间腐蚀深度增加,疲劳寿命缩短,断裂位置由焊缝区向5052铝合金母材转变。

5052铝合金本构模型和断裂模型研究

为了探究铝合金的成形性能,需要建立正确的材料模型以反映材料的变形行为和断裂现象,设计了单轴拉伸、平面应变和压缩3种各向异性试样以及两端缺口、中心圆孔和剪切3种断裂试样,结合数字图像相关法进行试验。基于试验和建模,标定了Yld2000-3d各向异性屈服准则、Swift-Voce硬化模型以及DF2014断裂模型。结果表明:5052铝合金具有明显的各向异性,采用Yld2000-3d各向异性屈服准则能准确表征铝合金的各向异性行为,Swift-Voce模型能准确预测缩颈之后的整段硬化曲线,利用DF2014断裂模型对5052铝合金的断裂行为进行预测,并结合有限元仿真得到断裂模型的参数,显示断裂模型能准确预测铝合金的断裂行为。

Effects of cold rolling and heat treatment on microstructure and mechanical properties of AA 5052 aluminum alloy

The microstructures and mechanical properties of homogenized-rolled AA5052 aluminum alloys with different rolling reductions and following annealing treatments were investigated by optical microscope, scanning electron microscope, X-ray diffractometer, micro-hardness and tensile tests. The results show that with increasing rolling reduction, the equiaxed grains are elongated along the rolling direction obviously, and accumulation of rolling reduction increases the work hardening effect, which results in the enhanced strength and degraded plasticity. When rolling reduction is 87%, the ultimate tensile strength reaches 325 MPa but elongation is only 2.5%. There are much more secondary phase precipitates after annealing treatment. With an increase of annealing temperature, the amount of precipitates increases and work hardening diminishes continuously. The elongation is improved to ~23% but the tensile strength is decreased to 212 MPa after annealing at 300 °C for 4 h, which are comparable to those of as-homogenized alloy.

3D FEM simulation of flow velocity field for 5052 aluminum alloy multi-row sprocket in cold semi-precision forging process

Based on the design of the multi-row sprocket with a new tooth profile,a cold semi-precision forging process for manufacturing 5052 aluminum alloy multi-row sprocket was presented.Through simulating the forging process of 5052 aluminum alloy sprocket billet with 3D rigid-viscoplastic FEM,both the distributions of flow velocity field in axial(U_Z),radial(U_R) and circumferential(U_θ) directions and the curves of velocity component in different deformation regions were respectively obtained.By comparison and analysis of the velocity varying curves,the velocity component relation conditions for filling the die cavity were clarified.It shows that when the die cavity is almost fully filled,the circumferential velocity U_θ increases sharply,implying that U_θplays a key role in fully filling the die cavity.

EIS Study on Pitting Corrosion of AA5083-H321 Aluminum-Magnesium Alloy in Stagnant 3.5% NaCl Solution

In this research, EIS （electrochemical impedance spectroscopy） technique was utilized to study the pitting corrosion behaviour of AA5083-H321 aluminum-magnesium alloy in 3.5% NaCl solution. Impedance spectra were obtained during 240 h of exposure of the sample to the test solution. The surface and cross-section of the samples were studied by scanning electron microscopy （SEM） and EDAX （energy dispersive analysis of X-ray） analysis. The results indicated that as the resistance of the passive layer on intermetallic particles is very small, this parameter on the sample surface layers is controlled by that of pure passive layer. However, the capacitors in the proposed equivalent circuit are replaced with the constant phase elements （CPE）, due to non-uniformity and occurrence of pitting corrosion on the surface. The outward diffusion of Al^＋3 ions through the passive layer and the thickening of this layer cause the impedance decrease in the first 24 h and increase afterwards. The detachment of intermetallic particles from some of pits and the accumulation of the corrosion products inside some others are factors that prevents the continuation of cathodic reactions on the top of the intermetallic particles.

Role of Chloride Ion and Dissolved Oxygen in Electrochemical Corrosion of AA5083-H321 Aluminum-Magnesium Alloy in NaCl Solutions under Flow Conditions

Flow-induced corrosion consists electrochemical and mechanical components. The present paper has to assessed the role of chloride ion and dissolved oxygen in the electrochemical component of flow induced corrosion for AA5083-H321 aluminum-magnesium alloy which is extensively used in the construction of high-speed boats, submarines, hovercrafts, and desalination systems, in NaCI solutions. Electrochemical tests were carried out at flow velocities of 0, ：2, 5, 7 and 10 m/s, in aerated and deaerated NaCI solutions with different sodium chloride concentrations. The results showed that the high rate of oxygen reduction under hydrodynamic conditions causes an increase in the density of pits on the surface. The increase of chloride ions concentration under flow conditions accelerates the rate of anodic reactions, but have no influence on the cathodic reactions. Thus, in the current work, it was found that under flow conditions, due to the elimination of corrosion products inside the pits, corrosion resistance of the alloy is increased.

Effect of semi-solid processing on microstructure and mechanical properties of 5052 aluminum alloy

The microstructure and mechanical properties of rheocasted 5052 aluminum alloy were investigated.The semi-solid slurry of this alloy was prepared by ultrasonic vibration(USV) process and then shaped by gravity casting(GC) and high press diecasting(HPDC).The experimental results indicate that fine and globular primary α(Al) particles are distributed uniformly in the rheocasting samples.The tensile strength and elongation of the rheo-GC sample are 191 MPa and 7.5%,respectively.Compared with the conventional GC samples,they increase by 22.4% and 82.9% respectively.The tensile strength and elongation of the rheo-HPDC samples reach 225 MPa and 8.6%,respectively,and they are 14.8% and 75.5% higher than those of the conventional HPDC samples,respectively.It is also found that the ductile fracture mode prevails in the rheocasting samples.

Dissimilar friction stir welding between 5052 aluminum alloy and AZ31 magnesium alloy

Dissimilar friction stir welding between 5052 Al alloy and AZ31 Mg alloy with the plate thickness of 6 mm was investigated.Sound weld was obtained at rotation speed of 600 r/min and welding speed of 40 mm/min.Compared with the base materials,the microstructure of the stir zone is greatly refined.Complex flow pattern characterized by intercalation lamellae is formed in the stir zone.Microhardness measurement of the dissimilar welds presents an uneven distribution due to the complicated microstructure of the weld,and the maximum value of microhardness in the stir zone is twice higher than that of the base materials. The tensile fracture position locates at the advancing side(aluminum side),where the hardness distribution of weld shows a sharp decrease from the stir zone to 5052 base material.

Formation of Aluminum-magnesium Alloy Cup by Hydrodynamic Deep Drawing with Twin-loading Paths

In order to overcome the limitation of hydro-rim deep drawing, a new process of hydrodynamic deep drawing （HDD） with independent radial hydraulic pressure was proposed. By employing the dynamic explicit analytical software ETA/DynaformS.5 which is based on LS-DYNA3D, the effects of independent radia! hydraulic pressure on the stress, strain and the sheet-thickness of aluminum-magnesium cylindrical cup with a hemispherical bottom were analyzed by numerical simulation. The feature of stress distribution is that there exists a stress-dividing circle in the flange, and the radius of dividing circle was determined by theoretical analysis and stimulation. The experimental results indicate that the reasonable match of independent radial hydraulic pressure and liquid chamber pressure can effectively reduce the thinning at the bottom of hemisphere, decrease the radial stress-strain, and improve the drawing limit of aiuminum-magnesium alloy cylindrical cup.

Friction stir butt welding of A5052-O aluminum alloy plates

Friction stir butt welding (FSW) between A5052-O aluminum alloy plates with a thickness of 2 mm was performed.The rotation speeds of the welding tool were 2000 and 3000 r/min,respectively.The traverse speed was ranged from 100 mm/min to 900 mm/min.The defect-free welds with the very smooth surface morphology were successfully obtained,except for at the welding condition of 3000 r/min and 100 mm/min.The onion ring structure was observed in the friction-stir-welded zone (SZ) at the condition of 2000 r/min and 100 mm/min.For all the welding conditions,the grain size of the SZ was smaller than that of the base metal,and was decreased with the decrease of the tool rotation speed and with the increase of the tool traverse speed.The stir zone exhibited higher average hardness than the base metal.The decrease of the tool rotation speed and the increase of the tool traverse speed resulted in the increase in the average hardness of the SZ.The tensile strength of the FSWed plates was similar to that of the base metal,except for at the welding condition of 3000 r/min and 100 mm/min.The total elongation of the FSWed plates was lower than that of the base metal.

基于响应面法的5052铝合金搅拌摩擦焊接工艺参数研究

目的 建立搅拌摩擦焊接工艺参数与焊接接头抗拉强度之间关系的响应曲面模型,并依此模型研究焊接工艺参数变化对接头抗拉强度所产生的影响,得到最佳工艺参数,提高焊接接头强度。方法 以5052-H112铝合金为研究对象,基于响应面法优化设计试验方法,以转速、焊接速度、轴肩压入深度为因素,焊接接头的抗拉强度为响应值设计试验,建立对应的响应函数与回归模型,对模型进行方差分析,根据模型得到最佳工艺参数值,并与试验结果作比较。结果 成功建立了响应模型,在分析模型和试验验证后发现,在选定的工艺参数范围内,当转速为737 r/min、焊接速度为60 mm/min、轴肩压入深度为0.3mm时,接头抗拉强度达到最优值227MPa。结论 通过响应面分析得到,转速和焊接速度对抗拉强度的影响最大,且两者交互作用显著,在给定范围内随着转速和焊接速度的提高,抗拉强度增大至峰值后下降,轴肩压入深度单独对接头抗拉强度的影响较小,其与转速交互影响显著。通过响应曲面法优化后的焊接工艺参数明显提高了5052-H112铝合金搅拌摩擦焊焊接头抗拉强度。

5052铝合金板材阳极氧化条纹的形成机理

针对5052铝合金板带材阳极氧化后出现表面条纹缺陷的现象,借助扫描电镜、光学显微镜等对缺陷的产生原因进行分析,并提出改善缺陷的措施.结果表明,表面条纹缺陷与第二相种类和尺寸、晶粒均匀性等密切相关.通过大幅降低Fe含量等措施可显著改善阳极氧化条纹缺陷.

5052铝合金阳极氧化料基材边部“发白”分析及对策

5052-H32阳极氧化料边部发白是氧化料基材生产中一个比较难彻底解决的问题。针对5052-H32铝合金基材边部发白部分,采用粗糙度仪检测表面粗糙度,采用金相显微镜观察缺陷微观形貌并选用扫描电镜进行形貌分析和能谱化学成分分析。分析发白色差部分产生的原因,并结合实际生产情况以及实验进行验证。通过对卷材存放条件、轧制油品、清洗过程以及退火工艺等方面的改进,使双边部发白色差缺陷卷出现的概率大幅降低,效果显著,基本解决了发白色差对氧化料生产过程的影响。

在线细化及处理工艺对5052铝合金阳极氧化料材料线的影响

材料线是5052铝合金阳极氧化料的一个主要缺陷。通过对该合金产品缺陷的取样分析,发现缺陷为铸锭内部冶金质量所致。缺陷主要有两种,一种为氧化物夹杂,一种为钛硼化合物夹杂。根据缺陷分析结果,对形成该缺陷的原因进行了机理分析,其成因主要与熔体在线处理有关,包括细化剂的种类、用量、本身质量、在线除气装置中氯气的使用与否以及在线除气装置清理维护频次等有关。