激光定向能量沉积Al-Mg-Sc-Zr修复5083-H112铝合金的组织和性能

激光定向能量沉积增材修复技术具有时间短、效率高、成本低、力学性能好等优点,具有很大的发展潜力。采用Al-7.5Mg-0.3Sc-0.28Zr作为修复材料对轨道交通用5083-H112铝合金进行激光修复实验,得到了致密、无缺陷的修复试样,并对其组织和性能进行研究,探讨了激光修复铝合金的可行性。结果表明,熔合线附近过渡区可划分为修复区、部分熔化区、热影响区和母材。修复区为完全等轴晶,由平均晶粒尺寸为4.95μm的细晶带和18.34μm的粗晶区组成。从修复区到部分熔化区再到热影响区的过渡区域,Al元素含量逐渐升高,Mg元素含量逐渐下降,硬度逐渐下降,修复后母材未被软化。由于激光增材制造技术的快速凝固,在熔合线附近的细晶带有较大的应力集中,由于较小的热输入在部分熔化区、热影响区的残余应力较小。修复试样的屈服强度为(152±2)MPa,为母材的89.4%;抗拉强度为(305±5)MPa,为母材抗拉强度的100%;伸长率为(15.5±0.5)%,为母材的85.2%;断裂发生在强度较弱的母材。高性能的激光修复铝合金是可实现的,具有广泛的应用前景。

Microforming of superplastic 5083 aluminum alloy

The mechanical behavior of superplastic 5083 aluminum alloy during microforming process was investigated by finite element analysis.A micro V-groove die was modeled to analyze the effects of forming time,load and temperature on the microformability of the 5083 aluminum alloy.First,the microformability of the 5083 aluminum alloy was estimated using a microformability index.The simulation results show that the microformability increases with the forming load,time and temperature increasing.Superplasticity of the 5083 aluminum alloy during microforming using the V-groove die was also investigated in terms of the effective strain rate.The results show that the superplasticity of the 5083 aluminum alloy occurs in a specific part of the material for a specific period during the microforming process depending on the forming conditions and the microformability index.

Joint performance of CO_2 laser beam welding 5083-H321 aluminum alloy

Laser beam welding of aluminum alloys is expected to offer good mechanical properties of welded joints. In this experimental work reported, CO2 laser beam autogenoas welding and wire feed welding are conducted on 4 mm thick 5083- H321 aluminum alloy sheets at different welding variables. The mechanical properties and microstructure characteristics of the welds are evaluated through tensile tests, micro-hardness tests, optical microscopy and scanning electron microscopy （SEM）. Experimental results indicate that both the tensile strength and hardness of laser beam welds are affected by the constitution of filler material, except the yield strength. The soften region of laser beam welds is not in the heat-affected zone （ HAZ ）. The tensile fracture of laser beam welded specimens takes place in the weld zone and close to the weld boundary because of different filler materials. Some pores are found on the fracture face, including hydrogen porosities and blow holes, but these pores have no influence on the tensile strength of laser beam welds. Tensile strength values of laser beam welds with filler wire are up to 345.57 MPa, 93% of base material values, and yield strengths of laser beam welds are equivalent to those of base metal （264. 50 MPa）.

Fabrication of anodized superhydrophobic 5083 aluminum alloy surface for marine anti-corrosion and anti-biofouling

Marine corrosion and biofouling seriously affect the service life of marine structural materials,resulting in performance failure,enormous economic loss,and even catastrophic safety accidents.It is worthwhile and desirable to develop high-efficiency strategy for anti-corrosion and anti-biofouling.In this paper,superhydrophobic 5083 aluminum alloy(AA5083)surface with micro-nano hierarchical morphology was fabricated through anodization followed by 1H,1H,2H,2H-perfluorooctyltriethoxysilane(POTS)modification.The surface morphologies,roughness,and chemical compositions were revealed by scanning electron microscopy,atomic force microscopy,and X-ray diffraction.The self-cleaning ability,corrosion resistance and algae adhesion suppression ability of the fabricated surfaces were investigated,indicating an excellent water-proofing,anti-corrosion and anti-biofouling performance.We believe the superhydrophobic creation of metallic materials is expected to have potential applications in marine corrosion and antibiofouling fields.

Corrosion Mechanism of 5083 Aluminum Alloy in Seawater Containing Phosphate

As a material with good corrosion resistance,5083 aluminum alloy has a great application prospect in marine environment.In this work,the corrosion characteristics of 5083 aluminum alloy in seawater containing phosphate were investigated with Potentiodynamic Polarization,Electrochemical Impedance Spectroscopy (EIS),Scanning Electron Microscope (SEM),Energy Dispersive Spectroscopy Analysis (EDSA),X-ray Photoelectron Spectroscopy (XPS) and Laser Confocal Microscope.The results indicated that the effects of phosphate in seawater were two-fold.Firstly,phosphate slightly accelerated the corrosion of 5083 in seawater in the early stage of corrosion.HPO_4~(2-)competed with OH~-in the adsorption process on the alloy surface,which weakened the contact between OH~-and Al~(3+)near the interface of the alloy,and inhibited the formation as well as the self-repair of the passive film,thus accelerating the activation dissolution process.Compared with the natural seawater,the charge transfer resistance of 5083 in the seawater containing phosphate decreased faster during the early stage of corrosion,and the corrosion current density i_(corr) was higher in seawater containing phosphate.On the other hand,the addition of phosphate would not affect the cluster distribution of the second phase of 5083 in seawater,but it changed the composition of the corrosion product layer and had an obvious inhibitory effect on the local corrosion of 5083 in seawater.After 16-day exposure,shallower and more sparsely distributed pits could be observed on the derusted surface of 5083 in the seawater containing phosphate,and the pitting coefficient in the seawater containing phosphate was significantly lower than that in natural seawater.The reduction of pitting tendency could be realized mainly through two ways.First,the HPO_4~(2-)adsorbed on the surface of the passive film in the early stage of corrosion and repeled the corrosive anions such as Cl~-.Second,phosphate participated in the construction of the Ca HPO_4 precipitation film,which acted as a barrier and protection.

Significant improvements in mechanical properties of AA5083 aluminum alloy using dual equal channel lateral extrusion

Dual equal channel lateral extrusion (DECLE), as a severe plastic deformation (SPD) process, was employed forimproving the mechanical properties of AA5083 aluminum alloy. Several experiments were conducted to study the influences of theroute type, namely A and B, and pass number on mechanical properties of the material. The process was conducted up to 6 passeswith decreasing process temperature, specifically from 573 to 473 K. Supplementary experiments involving metallography, hardnessand tensile tests were carried out in order to evaluate the effects of the process variables. The hardness measurements exhibitedreasonably uniform distributions within the product with a maximum increase of 64% via a 6-pass operation. The yield and ultimatestrengths also amended 107% and 46%, respectively. These significant improvements were attributed to the severe shear deformationof grains and decreasing pass temperature, which intensified the grain refinement. TEM images showed an average grain sizereduction from 100 μm for the annealed billet to 200 nm after 6 passes of DECLE. Finally, the experimental findings for routes A andB were compared and discussed and some important conclusions were drawn.

5083铝合金搅拌摩擦焊接头拉伸行为研究

目的研究5083铝合金搅拌摩擦焊接(FSW)的组织、力学性能和拉伸应变,分析接头的拉伸行为。方法采用数码相机、光学显微镜、电子扫描显微镜等表征分析方法,对焊缝的表面宏观成形、微观组织、断口形貌进行分析;利用拉伸机、三维数字动态散斑应变测量分析系统和显微维氏硬度计对接头的力学性能和拉伸应变进行测试。结果不同焊接工艺参数下FSW接头的最低抗拉强度为305 MPa,断后延伸率达到了14%以上;焊核区拉伸应变沿板厚方向呈现上高下低和上宽下窄的不均匀梯度分布,发生了较大程度的变形强化,直到拉伸应力达到抗拉强度。断裂失效前300/120接头的最大拉伸应变在晶粒粗大的母材区,500/120和500/200接头的最大拉伸应变则位于晶粒尺寸差异较大的后退侧焊核区与热力影响区交界处。接头拉伸断口宏观上均为45°剪切韧性断裂,微观上均以韧窝韧性断裂为主,而高热输入500/120接头出现脆性断裂特征,其延伸率明显降低。结论高热力耦合输入使铝合金FSW接头薄弱区发生转变,强韧性降低。

5083铝合金搅拌摩擦焊缝多区域力学性能研究

对12 mm厚的5083铝合金双轴肩搅拌摩擦焊接头不同区域进行金相组织观察、拉伸试验、硬度测试和疲劳试验,对疲劳试验后的试样断口进行SEM观察。结果表明:焊核区晶粒明显细化,热影响区晶粒粗化,热机影响区晶粒发生严重变形并带有方向性。接头整体硬度近似呈非对称的“W”形分布。从母材到焊核区硬度先减小后增大。母材硬度值最高,焊核区次之。母材、焊核区、热影响区的疲劳寿命差别较大,母材疲劳性能最好,焊核区次之,热影响区最弱。各区的疲劳裂纹源位于疲劳试样的表面,扩展区中可以看到疲劳条带,瞬断区断裂形式均为韧性断裂。

Unified Principal S-N Equation for Friction Stir Welding of 5083 and 6061 Aluminum Alloys

With the popularization of friction stir welding(FSW),5083-H321 and 6061-T6 aluminum alloy materials are widely used during the FSW process.In this study,the fatigue life of friction stir welding with two materials,i.e.,5083-H321 and 6061-T6 aluminum alloy,are studied.Fatigue tests were carried out on the base metal of these two materials as well as on the butt joints and overlapping FSW samples.The principle of the equivalent structural stress method is used to analyze the FSW test data of these two materials.The fatigue resistances of these two materials were com-pared and a unified principal S-N curve equation was fitted.Two key parameters of the unified principal S-N curve obtained by fitting,Cd is 4222.5,and h is 0.2693.A new method for an FSW fatigue life assessment was developed in this study and can be used to calculate the fatigue life of different welding forms with a single S-N curve.Two main fatigue tests of bending and tension were used to verify the unified principal S-N curve equation.The results show that the fatigue life calculated by the unified mean 50%master S-N curve parameters are the closest to the fatigue test results.The reliability,practicability,and generality of the master S-N curve fitting parameters were verified using the test data.The unified principal S-N curve acquired in this study can not only be used in aluminum alloy materials but can also be applied to other materials.

轨道交通车辆用5083铝合金单边角接接头的疲劳性能研究

针对轨道交通车辆常用4 mm厚5083铝合金板材单边角接焊接接头展开疲劳性能研究,求得其单边角接焊接接头的S-N曲线及条件疲劳极限。采用金相显微镜、扫描电镜观察接头微观组织和疲劳断口,分析了其疲劳断裂机理。研究结果表明,5083铝合金角焊缝焊接接头微观组织均匀,无微裂纹。焊缝中心硬度最低,硬度值随焊缝中心距离增大而增大,到达母材后硬度值趋于稳定;单边角接接头立板与底板间的抗拉强度仅为110 MPa,远低于母材的324.5 MPa;在加载107条件下,中值疲劳极限为7.33 MPa,仅为母材强度的2.25%,说明沿立板方向承受交变载荷时疲劳性能较差;疲劳裂纹萌生于焊缝根部,由于焊缝内部存在气孔等缺陷,导致疲劳断口存在多个裂纹源。综上,设计5083铝合金单边角接接头时,立板不应承受交变载荷。

冷轧及退火工艺对5083铝合金薄板组织性能的影响

利用金相显微镜、拉伸试验机、弯曲试验机对5083O铝合金板材在不同冷轧加工率(5%~40%)和不同退火温度(120~280℃)下的微观组织、拉伸力学性能、弯曲性能进行了系统研究。研究结果表明,5083O铝合金板材晶粒为细小均匀的等轴晶。随着冷轧加工率从5%增加至40%,晶粒逐渐被压扁、拉长。冷轧加工率不大于10%的板材折弯性能良好;当冷轧加工率为20%时,弯曲样品外侧出现凹凸不平的颈缩区域;当冷轧加工率增加到30%时,折弯样品出现微裂纹;当加工率增加到40%时,裂纹数量增多、尺寸增大。随着退火温度从120℃增加到280℃,不同冷轧加工率的板材屈服强度和抗拉强度呈单调下降趋势,而且屈服强度的降幅大于抗拉强度的降幅,断后伸长率呈单调增加趋势。当冷轧加工率为20%时,需对板材进行200℃以上的退火处理才能满足折弯性能要求;当冷轧加工率增加至30%和40%时,需要对板材进行240℃以上的退火处理才能满足折弯性能要求。

电池包用5083铝合金断裂失效研究

随着汽车安全法规的逐渐严苛、新能源汽车轻量化趋势的不断深入,电池包安全成为新能源车型安全的核心。文章以主要应用于新能源汽车电池包侧护板的5083铝合金为研究对象,通过铝合金静态拉伸、动态拉伸、静态缺口拉伸、中心孔拉伸、剪切、拉剪等试验获得了铝合金在不同应力状态下的力学性能,采用自研软件建立和标定了材料应变硬化曲线和修正莫尔-库仑(MMC)断裂损伤模型参数,并通过三点弯曲试验和动态穿孔验证了MMC失效模型的合理性。结果表明,本研究中得到的失效模型可以较好地预测5083铝合金断裂失效行为,为新能源汽车电池包的安全性能分析提供了有力的材料数据基础。

Growth and corrosion behaviors of thin anodic alumina membrane on AA5083 Al-Mg alloy in incalescent medium

A self-ordered porous film was fabricated on aluminum alloy in a ternary boric-sulfuric-oxalic acid electrolyte system. By means of voltage–time response, the oxidation process as well as the growth efficiency was studied. Field emission scanning electron microscopy（FE-SEM） was adopted to reveal the morphological and microstructural features of as-fabricated oxide layers. The corrosion protection properties of the films were investigated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The results showed that increasing the concentration of the double ionic layer located at the oxide interface could accelerate the film growth rate. The anodic oxidative layer with thickness of 8-9 μm and pore diameter of 10-14 nm maintains the pattern and topography of workpieces, compared with the overall closed film with hierarchical structure. Both samples exhibited much lower corrosion current density after boil water sealing. Meanwhile, a superior stability could be achieved through raising the ambient temperature.

5083铝合金GTN损伤参数求解与成形极限预测

GTN(Gurson-Tvergaard-Needleman)损伤模型被广泛用于预测金属的韧性断裂,但损伤参数多且求解困难,限制了其实际应用。以5083铝合金为研究对象,通过扫描电镜观察不同变形阶段拉伸试样的孔洞体积占比确定GTN损伤参数的取值范围;借助中心复合实验设计方法构造拉伸曲线关键变量与GTN损伤参数的响应曲面模型,应用NSGA-II遗传算法优化铝合金板料的损伤参数;将优化后的GTN损伤参数应用于有限元分析中,利用数值模拟方法预测5083铝合金的成形极限图(FLD),并通过Nakazima试验测得铝合金板料的FLD,与数值模拟结果进行对比分析。研究结果表明:GTN损伤模型预测的FLD与实验结果的相对误差在10%以内,且拉压变形区域的预测精度高于双拉变形区域的预测精度。

环波反复模压和扭转工艺制备高性能5083铝合金

提出一种高性能5083铝合金板材的制备工艺。该工艺为温热条件下基于循环应力状态进行的反复模压-扭转强变形过程。研究表明:当温度为200℃时,二次变形后晶粒细化效果最好,平均晶粒尺寸从24μm细化到12.5μm;当温度为300℃时,一次变形后板材的力学性能最好。抗拉强度(397 MPa)和断裂伸长率(28.3%)分别比原板提高30%和60%。第二相粒子和再结晶晶粒通过第二相强化和细晶粒强化来提高材料的强度。等轴再结晶晶粒则提高了材料的塑性和韧性。

5083铝合金动车车窗超塑气胀成形工艺

超塑气胀成形工艺是复杂薄壁零件成形的主要技术.以5083铝合金为研究对象,利用Marc有限元软件对动车车窗的超塑气胀成形工艺进行研究,选择合适的正反胀时间和压力,设计了3套不同的反胀模具(底面左上端圆角大小不同以及左端是否有凸槽),依次进行热冲压、反胀及正胀有限元分析,最终得出正确的超塑气胀成形模具.结果表明:反胀过程中储料的多少对成形件有显著影响;其中两种成形件的右边储料过多,刚性太大,正胀时难以变形,出现褶皱缺陷,而另外一种成形件由于模具左端设有凸槽减少了储料,刚性也减小,故易于变形且无明显缺陷;成形件最小壁厚为2.496 mm,位于车窗内边缘棱边处,最大减薄率为37.6%,与模具贴合良好且质量稳定,整体壁厚分布均匀.

深冷处理对5083铝合金的组织及性能的影响

采用液相法和急冷急热的方法在-196℃下,深冷处理时间(6 h、24 h和28 h)和深冷处理次数(1次、2次、3次和5次)参数下对5083铝合金进行深冷处理。通过金相显微镜、扫描电子显微镜(SEM)、涡流电导仪、万能试验机、电化学工作站等分别对5083铝合金的组织及力学性能、耐蚀性能等进行分析。研究结果表明:深冷处理能细化合金晶粒,且在深冷时间为6 h时,晶粒更加均匀细小且合金抗拉强度和屈服强度分别提高至410.7 MPa和152.5 MPa,而电导率并无明显下降。同时,材料的自腐蚀电流较未处理的样品降低了65.7倍,电压提高了24.9%,阻抗弧半径增加,材料的耐腐蚀性能得到显著提高。深冷次数为2次时,试样的力学性能和耐腐蚀性能也得以提高。为了获得优良的力学和耐腐蚀性能的5083铝合金,可选择对其进行短时2次深冷或6 h单次深冷处理。

5083铝合金焊接接头高周疲劳行为研究

以5083铝合金MIG焊接头为研究对象,对其微观组织、显微硬度、高周疲劳性能以及疲劳断裂特征进行了研究。结果表明,接头焊缝区存在着密集分布的不连续点状析出物。与母材相比,接头处析出相分布更为密集,且尺寸更为粗大;然而,焊接接头的硬度却与母材相当,这主要与析出强化效果增强和形变强化效果消失有关。焊接接头107周次的中值条件疲劳强度Δσ为46.4 MPa。焊接接头的疲劳源有多个,疲劳裂纹萌生于疏松和未熔合等焊接缺陷处,疲劳裂纹扩展区出现了疲劳辉纹,瞬断区内有大量等轴韧窝。

Mg、Mn成分优化对5083铝合金组织和性能的影响

设计了不同Mg、Mn含量的5083铝合金,采用室温拉伸、硬度测试和剥落腐蚀等实验,研究了Mg、Mn含量变化对5083显微组织、力学性能和耐腐蚀性能的影响,得到了最优的成分。当Mg含量在4.3%~4.4%,5083的力学性能和耐腐蚀性能较高。Mn含量在0.7%~0.8%,5083力学性能较高;而当Mn含量在0.5%~0.6%时,5083剥落腐蚀程度较低。实验室条件下得到力学性能和耐腐蚀性能优良的5083铝合金的Mg含量为4.38%,Mn含量为0.61%,该成分合金退火状态下的抗拉强度为209.1 MPa,硬度为87 HV,断后延伸率为16.04%,剥落腐蚀等级为PA级。Mg在5083合金中能形成Mg_(2)Al_(3)相,复合相Al-Mg-Cr、Al-Mg-Mn-Fe脆硬相,会降低5083合金塑性和韧性。Mn在5083中能形成AlMn_(0.75)Fe_(2.25)、Fe_(19)Mn等相,Al-Mg-Mn-Fe、Al-Mn-Fe-Si、Al-Mn-Fe复合相与Al基体间的界面为剥落腐蚀的主要根源。

基于主成分及灰色关联度分析的5083铝合金FSW接头工艺参数优化

针对铝合金搅拌摩擦焊接工艺参数优化问题,对5083铝合金板材进行研究,开展其在不同搅拌摩擦焊工艺参数下的力学性能探索,运用主成分分析和灰色关联度分析法对试验结果进行探索,得出焊接接头最优工艺参数,并建立基于GRG的工艺参数二阶预测模型.结果表明,均值极差法得出最优工艺参数组合为转速1400 r/min,焊接速度1 mm/s,下压量0.3 mm,接头抗拉强度最大达到225.5 MPa,达到了母材的95.4%,失效位移为10.6 mm.在试验工艺参数范围内,影响接头抗拉强度的主要因素次序为下压量、焊接速度、转速;模型预测值与计算值无显著差异,回归模型与试验数据的吻合度好,说明预测模型可靠度高,此回归模型可作为其预测模型.创新点:(1)把主成分和灰色关联分析法应用到搅拌摩擦焊接工艺参数优化的研究中,采用正交试验,以较少的试验次数获得较优的焊接工艺参数.(2)构建基于灰色关联度的工艺参数二阶预测模型,分析模型拟合度和可靠性情况.