Liquid Phase Behavior during Elevated Temperature Deformation of the Fine-Grained 5083 Al Alloy

The liquid phase behavior of the fine-grained 5083 AI alloy obtained through thermomechanical process was investigated during the tensile tests in a temperature range of 380-570℃ and strain rate range of 4.17× 10^-4- 1.0× 10^-2 s^-1. The maximum elongation 530% of the fine-grained 5083 AI alloy was obtained at 550℃ and 4.17× 10^-4 s^-1. Fracture analysis by scanning electron microscopy （SEM） indicated that the formation of filament （formed by liquid phase） was greatly affected by the tensile temperature and strain rate. The results also showed that the optimum morphology of formed filament was obtained at 550℃ and a strain rate of 4.17× 10^-4 s^-1. The effect of liquid phase on superplastic deformation of the alloy was further discussed.

Deformation behavior of fine-grained 5083 Al alloy at elevated temperature

The microstructure evolution of the fine-grained 5083 Al alloy was investigated in annealing temperature range of 150−300℃.Then the effects of the different annealed microstructures on high-temperature deformation behavior were further studied.The results indicate that the initial recrystallization temperature is about 200℃.By tensile tests at 380−570℃and in strain rate range of 4.17×10^(−4)−1.0×10^(−2) s^(−1),the optimum superplastic parameters are obtained as follows:the annealed temperature 250℃,the tensile temperature 550℃and the strain rate 4.17×10^(−4) s^(−1).With the aid of scanning electronic microscopy(SEM),the fractography of the alloy after the superplastic deformation was analyzed.The results reveal that intergranular cavities with fine size and homogeneous distribution are beneficial to superplastic deformation.

Diversity of intergranular corrosion and stress corrosion cracking for 5083 Al alloy with different grain sizes

5083 Al alloy sheets with different grain sizes(8.7-79.2 μm) were obtained by cold rolling and annealing. Their microstructures, intergranular corrosion(IGC), stress corrosion cracking(SCC), and crack propagation behaviors were investigated. The results showed that samples with coarse grains exhibit better IGC resistance with a corrosion depth of 15 μm. The slow strain rate test results revealed that fine-grained samples exhibit better SCC resistance with a susceptibility index(ISSRT) of 11.2%. Furthermore, based on the crack propagation mechanism, grain refinement can improve the SCC resistance by increasing the number of grain boundaries to induce the corrosion crack propagation along a tortuous path. The grains with {011} orientation could hinder crack propagation by orientating it toward the low-angle grain boundary region. The crack in the fine-grained material slowly propagates due to the tortuous path, and low H;and Cl;concentrations.

Processing, characterization, room temperature mechanical properties and fracture behavior of hot extruded multi-scale B_4C reinforced 5083 aluminum alloy based composites

Microstructural characteristics and mechanical behavior of hot extruded Al5083/B4C nanocomposites were studied.Al5083and Al5083/B4C powders were milled for50h under argon atmosphere in attrition mill with rotational speed of400r/min.For increasing the elongation,milled powders were mixed with30%and50%unmilled aluminum powder(mass fraction)with meanparticle size of>100μm and<100μm and then consolidated by hot pressing and hot extrusion with9:1extrusion ratio.Hot extrudedsamples were studied by optical microscopy,scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),transmission electron microscopy(TEM),tensile and hardness tests.The results showed that mechanical milling process andpresence of B4C particles increase the yield strength of Al5083alloy from130to566MPa but strongly decrease elongation(from11.3%to0.49%).Adding<100μm unmilled particles enhanced the ductility and reduced tensile strength and hardness,but usingthe>100μm unmilled particles reduced the tensile strength and ductility at the same time.By increasing the content of unmilledparticles failure mechanism changed from brittle to ductile.

Corrosion and optimum corrosion protection potential of friction stir welded 5083-O Al alloy for leisure ship

Electrochemical tests were undertaken to determine the optimum conditions in seawater for corrosion protection of friction stir-welded 5083-O Al alloy.Polarization trend observations show that the limiting potential that avoids the effects of hydrogen embrittlement is -1.6 V,corresponding to the crossover point between concentration polarization and activation polarization.However,the optimum protection potential is between -1.5 and -0.7 V since the current density at these values is low in the potentiostatic tests.When a galvanic cell is formed in the seawater,the welds exhibit electrochemically stable trends.Welded parts in galvanic tests with various area ratios are stable and have excellent anticorrosion characteristics.

Superplasticity and Fracture Behavior of Fine Grained 5083 Al Alloy

The microstructure with uniform equiaxed fine gain was obtained by the thermo-mechanical processing （TMP） for the 5083 Al alloy （Al-4.56%Mg-0.61%Mn） plate. Uniaxial tensile test was carried out at a temperature range of 500-570 ℃ and a strain rate range of 4.17×10^-4 s-1^- 1×10^- 2 s^- 1. Maximum tensile elongation 530% was obtained at 550 ℃ and strain rate ε＆ =4 .17×10^-4 s^-1. Dislocations were observed in grain interiors and at grain boundaries during uniaxial tensile deformation by transmission electronic microscopy （TEM）, respectively. Results show that the grain boundary sliding （GBS） accommodated by dislocation motion is the principal reason for superplastic deformation. The cavities and fracture were observed during uniaxial tensile deformation of the alloy by scanning electronic microscopy （SEM）, indicating that linkage of cavities in large region would induce failure of the material. Moreover, presence of liquid phase at grain boundary also affects the superplastic deformation and behavior of cavities.

Superplasticity of Spray Deposited 5083 Al-Mg Alloy

The superplasticity of spray deposited and thermomechanical processed 5083Al-Mg alloy is investigated in this paper. The results show that spray deposited 5083 Al exhibits anequiaxed grain morphology with an average size of 15 m and porosity in the range of 0.1 vol. % to 5vol. % . Two distinct TMP procedures are employed to close porosity and refine grain size:extrusion plus rolling and direct rolling. The material processed using the former method exhibits arelatively high superplasticity with a maximum superplastic elongation of 465 % , whereas thatprocessed using the latter method exhibits a maximum superplastic elongation of 295 % . Materialsprocessed using extrusion plus rolling and direct rolling both exhibit similar stress-strainbehavior and strain rate sensitivity factors. The strain rate factors are in the 0.3 to 0.5 range.The difference in their superplastic elongation is possibly the result of differences in grain sizeand available cavity nucleation sites provided by closed gas pores.

Experimental and numerical assessment of energy absorption capacity of thin-walled Al 5083 tube produced by PTCAP process

The energy absorption capacity of the Al5083 thin-walled tube produced by parallel tubular angular pressing(PTCAP) process was evaluated. Also, microstructure, mechanical properties, and anisotropy coefficients were studied in the peripheral and axial directions. Results showed that values of energy absorption decreased with processing pass increasing and the values for the unprocessed, first and second passes were obtained to be 167, 161.4 and 160.7 J, respectively. The differences between the simulation results for the energy absorption values and their experimental values for the unprocessed, the first and the second PTCAP passes samples are about 5%, 10%, and 13%, respectively. The energy absorption capacity was related to the anisotropy coefficient and microstructure. The results demonstrated that grain refinement occurred and ultimate tensile strength(UTS) and microhardness after the first and second PTCAP passes were enhanced, while the increase rate in the first pass was much severer. Also, by applying PTCAP, the deformation modes were altered, such that the deformation mode of the annealed tube was quite symmetrical and circular while for the first and second passes there have been triple and double lobes diamond. The results of the numerical simulation for the deformation mode of the annealed and PTCAPed tubes were consistent with the experimental results. The deformation mode of tubes is dependent on their mechanical properties and variation of the mechanical properties during PTCAP process.

5083铝合金搅拌摩擦焊接头的微观组织与力学性能

通过金相分析、拉伸及断口形貌观察等方法研究8 mm厚5083铝合金搅拌摩擦焊接头的显微组织和力学性能。金相观察结果表明:焊核区由细小的等轴晶组织构成;热机影响区受机械和热的双重作用组织发生了较大程度的变形;热影响区仅受热循环的作用,与母材组织相似,但组织稍微有粗化现象。力学试验表明:焊接速度为160mm/min时,接头的抗拉强度可以达到327.3MPa,为母材强度的95.6%。断口形貌分析显示,接头的断裂模式为韧性和脆性的混合型断裂。

退火温度对 Mg-Li／Al 复合板界面组织与结合强度的影响

通过温轧制备5083Al/Mg-9.5Li-2Al/5083Al复合板,经200℃～400℃退火1h处理,利用扫描电子显微镜(SEM)和EDS对所制备的复合板进行显微组织结构观察,采用粘连法测试退火复合板的结合强度。结果表明,200℃温轧可以制备出界面结合良好的5083Al/Mg-9.5Li-2Al/5083Al复合板;复合板在350℃以上退火可形成连续的扩散层,扩散层由靠近镁锂合金一侧的Mg17Al12相和靠近铝合金一侧的Al3Mg2相组成,Li原子固溶于Al3Mg2相中;结合强度测试结果表明,当退火温度为350℃时,界面结合强度最高,达到了20MPa。

基于SWRXD的5083/6082异种铝合金搅拌摩擦焊接头的残余应力分布规律

以5083铝与6082铝为研究对象,利用搅拌摩擦焊(friction stir welding,FSW)制备了异种材料对接接头.利用短波长X射线衍射(short-wavelength X-ray diffraction,SWRXD)技术,以{311}与{111}为衍射晶面,基于极图最外圈织构参量确定了残余应力测试方向,采用d0法研究了FSW焊件中心层的残余应力.结果表明,{111}和{311}晶面测试的纵向残余应力分布趋势相近,焊核区为拉应力并出现两个应力峰值;{111}晶面的测试结果更为离散,应力的峰值向前进侧偏移;采用{111}晶面测试的横向的残余应力分布趋势与{311}晶面测试的结果偏差较大.

机械球磨和热挤压制备超细晶5083铝合金的显微组织与力学性能

采用室温机械球磨、热等静压和热挤压工艺制备超细晶5083铝合金,利用X射线衍射(XRD)、透射电镜(TEM)对材料的显微组织进行分析和观察,并对所制备材料的化学成分、密度、硬度和拉伸性能进行测定,在理论分析的基础上,半定量估算各种强化机制对材料强度的贡献。结果表明:制备的超细晶5083铝合金的平均晶粒尺寸为322 nm,相对密度为99.72%,屈服强度和抗拉强度分别为560 MPa和566 MPa,断后伸长率为6.3%;断裂方式为微孔聚集型断裂;强化机制包括细晶强化、弥散强化、固溶强化、位错强化,其中以细晶强化和弥散强化的贡献最大。

细晶5083铝合金非等温拉深工艺研究

通过实验研究了拉深凹模温度、拉深速度、压边间隙及润滑条件对细晶5083铝合金非等温拉深工艺的影响。实验结果表明:细晶5083铝合金板料在凹模温度为250℃以上具有良好的拉深成形能力。当凹模温度为275℃时,极限拉深比达到2.9;当在较佳的凹模温度不同的拉深速度下进行拉深时,得出细晶5083铝合金非等温拉深工艺在一定的拉深速度范围内对应变速率不敏感,在压头速度≤2mm/min时均能拉深成功。考虑了润滑层厚度和材料在升温过程中的热膨胀性能,通过实验得出的最佳压边间隙为1.9mm。选用水基石墨作为润滑剂,润滑层厚度达到0.3mm左右时拉深能够成功进行。

细晶5083铝合金不等厚板激光穿透焊接头的组织与性能

对细晶5083铝合金不等厚板进行了激光穿透焊试验,分析讨论了焊接接头的显微组织和力学性能。结果表明:从显微组织角度看,焊接接头可分为4个区域,即母材、热影响区、熔合区和焊缝中心区,各区域的组织有明显的特征;焊缝中心区为细小的等轴晶组织,通过TEM观察其晶粒大小约为1.5μm;焊接接头的显微硬度呈W形分布,热影响区较窄且软化趋势最明显;焊接拉伸试样的断裂位置在熔合区,接头的抗拉强度为186 MPa。

5083铝合金的高温压缩变形行为

在Gleeble-3500热模拟实验机上采用高温压缩实验研究了5083铝合金在变形温度为300~500℃、应变速率为0.01~10 s-1、真应变为0~0.9条件下的热变形行为。对高温压缩实验结果进行分析,修正了实验中由于摩擦和变形热效应引起的流变应力误差,得到5083铝合金修正后的真应力-真应变曲线。结果表明:在高温压缩实验过程中,摩擦和变形热效应产生的温升影响不能忽略,摩擦和温升引起应力变化的最大值分别为31.78、33.66 MPa;5083铝合金修正后的流变应力随变形温度的升高而降低,随应变速率提高而增大;应力峰值出现后,应力逐渐下降,且呈稳定的流变特性。

激光定向能量沉积增材修复5083铝合金组织与力学性能

以Al-Mg-Sc-Zr合金粉末作为修复原料,采用激光定向能量沉积法对开槽5083铝镁合金进行增材修复,用金相显微镜、扫描电镜、电子背散射衍射、室温拉伸试验及显微硬度测试等手段,研究5083铝合金试样修复前后的微观组织与力学性能,同时对不同修复体积占比的试样力学性能进行对比。结果表明:修复区熔合线附近柱状晶呈树枝状,垂直于熔合线方向向基体呈外延生长。修复区为典型的熔池分布,晶粒尺寸为4-9μm,存在较多孔洞,熔合线和扫描轨道附近析出大量Al_(3)(Sc,Zr)颗粒。5083基体材料与开槽修复件的抗拉强度相差不大,分别为190.80 MPa和197.73 MPa,但修复试样的伸长率显著降低。从基体至修复区的2 mm范围内,硬度均值(HV)从50逐渐提高至100。

5083铝合金H32板材的稳定化退火工艺

研究了冷轧变形程度、退火温度、保温时间等因素对5083合金板材力学性能和硬度的影响,确定了5083合金H32状态板材的稳定化退火工艺:加工率20%,退火温度150℃,保温时间2 h。在该工艺下合金的力学性能满足EN-485要求。

Parametric analysis of warm forming of aluminum blanks with FEA and DOE

The effect of temperature distribution on warm forming performance was investigated for 5083-O (Al-Mg) sheet metal blanks. Combined isothermal/non-isothermal FEA with design of experiments tools were used to predict appropriate warm forming temperature conditions for deep drawing and two-dimensional stamping cases. In the investigated temperature range of 25?250 ℃, the formability of Al-5083 alloy is found to be greatly dependent on the temperature distribution of the die and punch. To achieve increased degrees of forming, different temperature levels should be assigned to the corner and body of the die and punch. And the optimal temperature distributions for warm deep drawing and warm two-dimensional stamping are not identical.

5083铝合金板材折角加工的研究

研究了5083高强度铝合金板材折角加工性能,通过工艺试验,确定出铝合金板材冷加工的最佳方案和工艺参数,以确保铝合金板材冷加工成型质量,满足结构设计和隐身设计的要求。

均匀化热处理对5083铝合金难溶相与晶粒尺寸的影响

为研究5083铝合金均匀化过程中难溶相含量、种类以及晶粒尺寸的变化,采用金相显微镜(OM)、扫描电子显微镜(SEM)、能谱仪(EDS)、差示扫描量热仪(DSC)和X射线衍射仪(XRD)对材料组织进行表征。结果表明:铸态5083铝合金中的难溶相由Al(FeMnCr)相、Al(FeMnCr)Si相和Mg_(2)Si相组成。使用相图计算对铸态组织成分进行验证,结果与实验基本吻合。随着温度从460℃升高至560℃,导电率先升高后降低。这与组织中的弥散相析出和难溶相溶解有关。均匀化制度为540℃/10 h,560℃/10 h时,难溶相主要以针片状Al(FeMnCr)相为主,Mg_(2)Si相回溶充分,面积分数分别为0.730%和0.632%,未出现过烧组织的同时,晶内有明显的弥散相粒子析出。因此均匀化温度只有≥540℃才能实现5083铝合金凝固组织中部分难溶相的回溶。提高均匀化温度和延长均匀化时间均会增加晶粒尺寸,当均匀化温度小于540℃时,难溶相变化对晶粒长大影响不大,当均匀化温度大于540℃时,难溶相回溶的同时平均晶粒直径开始大于140μm。