Perforation of AA5083-H116 aluminium plates with conical-nose steel projectiles—experimental study

The interest regarding use of aluminium alloys in lightweight protective structures is today increasing. Even so, the number of experimental and computational investigations giving detailed information on such problems is still rather limited. In this paper, perforation experiments have been performed on AA5083-H116 aluminium plates with thicknesses varying between 15 and 30 mm impacted by 20 mm diameter, 98 mm long, HRC 53 conical-nose hardened steel projectiles. In all tests, initial and residual velocities of the projectile were measured and a digital high-speed camera system was used to photograph the penetration and perforation process. Based on these measurements, impact versus residual velocity curves of the target plates were constructed and the ballistic limit velocity of each target was obtained. An analytical perforation model from the open literature is then used to predict the ballistic limit velocity, and excellent agreement with the experimental data is found. The experimental results are finally compared to similar experiments on steel and concrete targets, and the capacity of the different materials is evaluated in relation to total weight.     

Perforation of AA5083-H116 aluminium plates with conical-nose steel projectiles – Calculations

The use of aluminium alloys in lightweight protective structures is increasing. Even so, the number of experimental and computational investigations that give detailed information on such problems is limited. In an earlier paper by some of the authors, perforation experiments were performed with 15–30 mm thick AA5083-H116 aluminium plates and 20 mm diameter, 98 mm long, HRC 53 conical-nose hardened steel projectiles. In all tests, initial and residual velocities of the projectile were measured and the ballistic limit velocity of each target plate was determined. In the present paper, an analytical perforation model based on the cylindrical cavity-expansion theory has been reformulated and used to calculate the ballistic perforation resistance of the aluminium plates. In addition, non-linear finite element simulations have been carried out. The target material was modeled with the Johnson–Cook constitutive relation using 2D axisymmetric elements with adaptive rezoning. To allow ductile hole growth, a pin-hole was introduced in the target. The analytical and numerical results have been compared to the experimental findings, and good agreement was in general obtained. A parametric study was also carried out to identify the importance of the different terms of the Johnson–Cook constitutive relation on the perforation resistance of the target. The results indicate that thermal softening cannot be neglected, so an alternative procedure for identification of the material constants in the power-law constitutive relation used in the cavity-expansion theory has been proposed.     

Mechanical,fatigue and microstructural properties of friction stir welded 5083-H111 and 6082-T651 aluminum alloys

In this study, 5083-H111 and 6082-T651 aluminum alloy plates in 6 mm thickness that are used particularly for shipbuilding industry were welded using Friction Stir Welding (FSW) method as similar and dissimilar joints with one side pass at PA position with the parameters of 1250 rpm tool rotation, 64 mm/min welding speed and 2° tool tilt angle. Tensile tests results showed sufficient joint efficiencies and surprisingly high yield stress values. Bending fatigue test results of all joint types showed fatigue strength close to each other. Fatigue strength order of the joints were respectively FSWed 5083-5083, and 6082-6082 similar joints and 5083-6082 dissimilar joint. Cross sections of the weld zones have been analyzed with light optical microscopy (LOM) and fracture surface of fatigue test specimens were examined by scanning electron microscopy (SEM). Although there were no voids in radiographic and microscopic analyzes, 5083-6082 joint showed rarely encountered voiding effect under fatigue load. Microhardness measurements revealed rare result for FSWed AW5083 and novel result for FSWed 6082 aluminum alloy.     

Low velocity perforation of AA5083-H116 aluminium plates

This paper presents an experimental and numerical investigation on low velocity perforation (in the velocity range 3.5–15.8 m/s) of AA5083-H116 aluminium plates. In the tests, square plates were mounted in a circular frame and penetrated by a cylindrical blunt-nosed projectile. The perforation process was then computer analysed using the nonlinear finite element code LS-DYNA in order to investigate the effects of anisotropy, dynamic strain aging (causing negative strain rate sensitivity) and thermal softening in low velocity impacts on the present aluminium alloy. Dynamic strain aging has been shown to influence both the predicted force level and fracture, while thermal softening only influences fracture prediction. No significant effect of plastic anisotropy has been observed.     

Perforation of aluminum plates with ogive-nose steel rods at normal and oblique impacts

Perforation experiments were conducted with 26.3 mm thick, 6061-T651 aluminum plates and 12.9 mm diameter, 88.9 mm long, 4340 R_c = 44 ogive-nose steel rods. For normal and oblique impacts with striking velocities between 280 and 860 m/s, we measured residual velocities and displayed the perforation process with X-ray photographs. These photographs clearly showed the time-resolved projectile kinematics and permanent deformations. In addition, we developed perforation equations that accurately predict the ballistic limit and residual velocities.     

Research on explosive welding of aluminum alloy to steel with dovetail grooves

In order to explore a new method for the explosive welding of aluminum alloy to steel, a 5083 aluminum alloy plate and a Q345 steel plate with dovetail grooves were respectively employed as the flyer and base plates. The parameters adopted in the explosive welding experiment were close to the lower limit of weldable window of 5083 aluminum alloy to Q345 steel. The bonding properties of 5083/Q345 clad plate were studied through mechanical performance tests and microstructure observations. The results showed that the aluminum alloy and steel plates were welded under the actions of metallurgical bonding and meshing of dovetail grooves. The tensile shear strength of 5083/Q345 clad plate met the requirements of the bonding strength of Al/Fe clad plate. The interfaces between aluminum alloy and the upper and lower surfaces of dovetail grooves were mainly welded through direct bonding, and discontinuous molten zone emerged in the local region; while the interface between aluminum alloy and the inclined surface of dovetail grooves was bonded by continuous molten layer. The brittle intermetallic compounds FeAl₂ and Al₅Fe₂ were generated at the bonding interfaces of 5083/Q345 clad plate. The fracture surface of the tensile specimen exhibited ductile and quasi-cleavage fractures.     

敏化时间对国产5083-H116铝合金组织与性能的影响

针对国产8 mm厚5083-H116铝合金,研究了敏化时间对其组织和性能的影响。结果表明,随着敏化时间的延长,5083铝合金微观组织中越来越多的β相（Al₃Mg₂）沿晶界析出,并且形成大量的网状结构;5083铝合金腐蚀电位降低,晶间腐蚀倾向性持续升高,强度降低,伸长率提高。     

Microstructural Study and Mechanical Properties of Dissimilar Friction Stir Welded AA5083-H111 and AA6082-T6 Reinforced with SiC Nanoparticles

Dissimilar friction stir welds were produced in 3 mm thick plates of AA6082-T6 and AA5083-H111 aluminum alloys using SiC as reinforcing material. The optimum weld presents a good distribution of nanoparticles in the weld nugget and mechanical mixing of the two alloys as well as further grain refinement compared to the one without nanoparticles. Higher hardness in the weld nugget is also evidenced, followed by enhanced ultimate tensile strength and elongation values. All specimens, after the tensile test, were lead to fracture at the heat affected zone of AA6082-T6 and specifically at the region of the lowest hardness.     

国产与进口5083-H116铝合金微观组织及疲劳裂纹扩展速率研究

研究了国产与进口5083-H116态铝合金轧制薄板材（厚度3 mm）的微观组织及其疲劳裂纹扩展行为。结果表明,国产与进口5083铝合金化学成分均满足相应标准要求。国产与进口5083铝合金显微组织均存在较多的粗大第二相,但后者的数量更多;相对于国产合金,进口合金晶粒尺寸更加细小、分布更加均匀。沿板材横、纵向,国产合金的抗拉强度和屈服强度皆高于进口合金,而延伸率相反。进口合金的疲劳裂纹扩展速率低于国产合金,在ΔK=15 MPa·m^1/2时,其裂纹扩展速率降低了32%以上。疲劳断口皆呈3个典型区域：裂纹萌生区均出现疲劳辉纹,相对于进口合金,国产合金较平坦且存在分层现象;稳态扩展区皆有明显疲劳辉纹,辉纹间距分别为0.405 5μm和0.282 3μm;瞬断区内,进口合金具有数量更多、尺寸更小的韧窝。     

Comparative evaluation of tungsten inert gas and laser beam welding of AA5083-H321

In this study, the bead-on-plate welds were made on AA5083-H321 alloy plates using both tungsten inert gas (TIG) welding and laser beam (LB) welding processes to study the enhancement of mechanical properties such as weld yield strength and hardness. The low heat input of laser beam welding effectively reduced the size of the fusion zone and heat affected zone compared to tungsten inert gas welding process. High speed LB welding and fast heating and cooling of LB welding process hinders grain growth compared to TIG welding process. The effect of vapourization of volatile alloying elements is also considered. It seems that magnesium evaporation is relatively less in LB welding compared to TIG welding. Tensile testing of the welded joints revealed that LB welding results in superior mechanical properties. It is concluded that LB welding process is more suitable to join AA5083-H321.     

Effect of projectile nose shape,impact velocity and target thickness on the deformation behavior of layered plates

The present study is based on the experimental and numerical investigations of deformation behavior of layered aluminum plates of different thicknesses under the impact of flat, ogive and hemispherical nosed steel projectiles. Thin-layered plates arranged in various combinations were normally impacted at different velocities with the help of a pneumatic gun. Ballistic limit velocity and the residual velocity of the projectiles for each layered combination were obtained experimentally as well as from the finite element code, and these were compared with those of the single plates of equivalent thicknesses. For two layers, the residual velocity was comparable to that of the single plate, however, when the number of layers was increased the velocity drop was found to be higher in the case of the single plate. Ogive nosed projectile was found to be the most efficient penetrator of the layered target. Hemispherical nosed projectile required maximum energy for perforation. Deformation profiles of the target plates in the layered combinations were measured, and it was found that hemispherical nosed projectile caused highest plastic deformation of target plates. Numerical simulation of the problem was carried out using finite element code ABAQUS. Explicit solution technique of the code was used to analyze the perforation phenomenon. Results of the finite element analysis were compared with experiments and a good agreement between the two was found.     

Mechanical and microstructural properties of robotic Cold Metal Transfer (CMT) welded 5083-H111 and 6082-T651 aluminum alloys

5083-H111 and 6082-T651 aluminum alloys used particularly in shipbuilding industry especially for the sake of their high corrosion resistance and moderate strength, were welded using Pulsed Robotic Cold Metal Transfer (CMT)-Metal Inert Gas (MIG) technology. Joints were fabricated as both similar and dissimilar alloy welds using plates with a thickness of 6 mm. Non-destructive tests such as visual and radiological examination were conducted before further destructive tests. Tensile, bend and fatigue tests were applied to specimens extracted from welded joints. Fracture surfaces of fatigue samples were examined by light optical microscopy (LOM) and scanning electron microscopy (SEM). Also macro and microstructures of weld zones were investigated and micro hardness profiles were obtained. In accordance with results, CMT-MIG provides good joint efficiency with high welding speed, and good tensile and fatigue performance.     

5083铝合金的热变形组织演变及晶粒度模型

通过等温压缩实验、光学显微镜与透射电镜研究了变形温度300~450℃、应变速率0.01~1s-1、真应变0.36~1.2范围内变形条件对5083铝合金热变形组织演变的影响。结果表明:升高热变形温度或降低应变速率均可促进5083铝合金的动态再结晶发生,使变形后5083铝合金位错密度降低,再结晶晶粒尺寸增大;随着应变量的增加,变形后合金的位错密度降低,动态再结晶程度增大。根据唯象理论的指数模型,利用线性回归方法建立了5083铝合金动态再结晶晶粒度模型,模型计算值与实测值吻合良好,平均相对误差仅为4.6%。     

温成形中铝合金板成形极限图的预测研究

在铝合金板温成形数值仿真中,成形极限图是判断材料颈缩失效和评价温冲压成形能力的基础.提出了一种温成形条件下铝合金板成形极限图的理论预测方法.采用曲线拟合方法建立了Al5083-O铝合金板应变硬化指数、应变率硬化指数随成形温度的变化规律;采用M-K理论模型,结合Logan-Hosford屈服函数计算获得温成形条件下铝合金板的成形极限图.计算结果与实验数据吻合较好,证实了温成形条件下铝板成形极限图的理论预测方法是正确的.     

Penetration into ductile metal targets with rigid spherical-nose rods

We developed penetration equations for rigid spherical-nose rods that penetrate ductile metal targets. The spherical cavity-expansion approximation and incompressible and compressible elastic-perfectly plastic constitutive idealizations simplified the target analyses, so we obtained closed-form penetration equations. We compared predictions from our models with previously published penetration data and results from Lagrangian and Eulerian wavecodes.     

Nanostructural and electrochemical characteristics of cerium oxide thin films deposited on AA5083-H321 aluminum alloy substrates by dip immersion and sol-gel methods

In this paper nano sized cerium oxide coating were applied by sol-gel and conversion (dip immersion) method on AA5083-H321 aluminum alloy. Nanostructural and phase properties of nano sized cerium oxides were investigated by SEM, EDX and AFM studies. Potentiodynamic polarization and EIS tests have been used to study corrosion behavior of nano sized cerium oxide films in 3.5% NaCl. Results indicated that cerium oxide which obtained by sol-gel method performed better corrosion and pitting resistance compared with dip immersion method.     

Thermomechanical buckling of hybrid cross-ply laminated rectangular plates

A thermomechanical buckling analysis is presented for simply supported rectangular symmetric cross-ply laminated composite plates that are integrated with surface-mounted piezoelectric actuators and are subjected to the combined action of in-plane compressive edge loads, two types of thermal loads, and constant applied actuator voltage. The formulation of equations is based on the classical laminated plate theory and the von-Karman non-linear kinematic relations. The analysis uses an exact method to obtain closed-form solutions for the buckling load. The effects of applied actuator voltage, thermal and mechanical loads, plate geometry, and lay-up configuration of the laminated plates are investigated. The novelty of the present work is to obtain closed-form solutions for electro-thermomechanical buckling of hybrid composite plates, and to cover non-uniform temperature distribution loading. The results for various states are verified with known data in the literature.     

Analysis of isotropic and multilayered plates and shells by using a generalized higher-order shear deformation theory

This paper introduces a generalized 5 degrees of freedom (DOF) higher-order shear deformation theory (HSDT) to study the bending and free vibration of plates and shells, which may be used to create other HSDTs. It also introduces a new HSDT for shells that is more accurate than many available HSDTs despite having the same 5DOF, and which is also able to reproduce the well-known Soldatos’ HSDT as special case. The governing equations and boundary conditions of the generalized formulation are derived by employing the principle of virtual work. These equations are solved via Navier-type closed-form solutions. Static and dynamic results are presented for plates and cylindrical and spherical shells with simply supported boundary conditions. Panels are subjected to sinusoidal, distributed and point loads. Results are provided for thick to thin as well as shallow and deep shells. Results from the new and well-known HSDTs introduced and reproduced based on the present generalized 5DOF HSDT are compared with the exact three-dimensional elasticity solution. The present new HSDT for plates and shells is found to be more accurate than the well-known HSDTs developed by other authors, for analyzing the static and free vibration of isotropic and multilayered composite plates and shells.     

Comparative analysis of perforation models of metallic plates by rigid sharp-nosed projectiles

Based on the mode of ductile hole enlargement, the present paper compares the models of a rigid sharp-nosed projectile perforating the ductile metallic target plate, given by Chen and Li [1] and Forrestal and Warren [2], respectively. It indicates that the formulae of ballistic limit and residual velocity of these two perforation models are consistent in form but with different applicable range, which due to them employing the spherical cavity expansion theory and cylindrical cavity expansion theory, alternately. Further analyses are conducted to discuss the effects of target material and plate thickness on the terminal ballistic performance with referring the experimental results of aluminum alloy and Weldox E steel plates. It is confirmed that the perforation mechanisms may transform with increasing the plate thickness and the strength of target material.     

冷喷涂Zn粉后5083铝合金的中温钎焊研究

以添加了5%(质量分数,下同)CsF-AlF3共晶钎剂的Zn粉为原料,采用冷喷涂技术在5083铝合金表面制备涂层,喷涂后的5083铝板在530℃进行钎焊连接。采用扫描电子显微镜结合能谱仪对涂层的显微结构及钎焊后的接头组织形貌进行观察与分析。结果表明:涂层与5083基体连接致密,钎剂颗粒呈絮状存在于Zn粒子交界面处;由于涂层对5083基体的保护,钎焊时5083基体表面没有出现Mg元素上浮现象,表面未形成复杂的氧化膜,530℃喷涂后的5083与1060可成功实现连接;钎焊接头组织均匀,主要由α铝基固溶体和β富锌基固溶体组成,存在少量孔洞缺陷。