Papers by Keyword: Aluminium Alloy Sheet

Abstract: Friction stir processing (FSP), with tilted parent metal is a new process, which consists in the use of an inclined base plate with an angle α = 1 - 3 º related to the table of the FSP processing machine, by mounting a calibrated part under one end of the base plate. Two clamping plates are fixed with screws on the base plate, and a sheet (parent metal, PM) or a workpiece is placed between the base plate and the clamping plates. The processing tool has the same tilt angle with respect to the sheet to be processed. Said parts are components of the jig for the process described. The processing tool performs a movement with the speed v(x), correlated with a simultaneous movement with the speed v(z) = v(x) tg α. The correlation is achieved by means of a program developed for the processing machine. Due to the tilt, during the FSP process, the leading edge of the rotating tool shoulder progressively enters the PM, continuously, at the point where the shoulder penetration depth in the PM is minimal. On the multifunctional friction processing machine, MMPF type, the processing by the described process of an aluminium alloy sheet, with the sizes 300 mm x 200 mm x 4 mm was performed. A hardened C45 steel tool was used, having the following technical characteristics: shoulder diameter 14 mm, smooth frusto-conical pin with a large diameter of 2.5 mm, a small diameter of 2.0 mm, and a height of 1.5 mm. The parameters had the following values: tilt angle α = 2° 6'; pin penetration depth h = 1.60 - 1.85 mm; tool speed n = 1500 - 2000 rpm; speed v(x) = 1 - 2 mm / s; speed (software correlated) v(z) = 0.03672181 * (1 - 2) mm / s; the temperature of the sheet behind the tool t = 240 - 420 °C. The appearance of the processed sheet is appropriate. No imperfections are observed. The results are appropriate. The tilted PM brings the following advantages of the process: the mechanical stress to produce burrs and / or chips on the surface of the PM decreases; the way the FSP process is carried out is improved, by reducing gap moving and vibrations; the appearance and mechanical characteristics of the processed areas are improved; the quality level of the executed products rises; wear of processing tools is reduced; energy efficiency increases; the electricity consumption of the machine decreases; productivity increases.

Abstract: Warm temperature biaxial stretching equipment was developed in order to observe equi-plastic work locus at elevated temperature. A thermostatic bath is installed in the conventional biaxial stretching machine, and a heat gun and an electric heater in the bath enable to heat the specimen up to 260°C. Since flow stress is affected by strain rate at warm temperature, the equipment enables stress ratio and strain rate controls at the same time. Equi-plastic work loci of AA5182-O was obtained by the developed apparatus at R.T., 170 and 260°C, and temperature dependence on biaxial deformation was discussed.

Abstract: To improve the accuracy of forming simulations for sheet metal, the use of material models calibrated by multiaxial material tests is essential. Adequate material models can be calibrated on the basis of the contours of equal plastic work obtained by multiaxial material tests. However, because the tests often require special experimental equipment, they are not widely used by the industry. This paper proposes a methodology for a numerical biaxial tensile test that uses ABAQUS, a popular commercial software package for finite element analysis. In numerical tests, an open-source user-defined material model (UMAT) is used to implement crystal plasticity models. In order to validate our methodology, we performed a numerical biaxial tensile test on a 6000-series aluminum alloy sheet, and the results were compared with those of biaxial tensile tests with a cruciform specimen. The results demonstrated that the proposed numerical biaxial tensile test provides a reasonable prediction of stress-strain curves and the contours of equal plastic work.

Abstract: This paper presents the main achievements of a research project aimed at investigating the applicability of the hot stamping technology to non heat treatable aluminium alloys of the 5052 H32 and heat treatable aluminium alloys of the 6016 T4P after six months natural aging. The formability and mechanical properties of 5052 H32 and 6016 T4P aluminum alloy sheets after six months natural aging under different temperature conditions were studied, the processing characteristics and potential of the two aluminium alloy at room and elevated temperature were investigated. The results indicated that the 6016 aluminum alloy sheet exhibit better mechanical properties at room temperature. 5052 H32 aluminum alloy sheet shows better formability at elevated temperature, and it has higher potential to increase formability by raising the temperature.

Abstract: Using SYSWELD to simulate welding temperature field for TIG welding of aluminum alloy sheet, The transient temperature field distribution and features of the thermal cycle curve is given. As a result, the calculated data is in good agreement with literature data, the model can provide a basis for technical parameters optimization during the process of TIG welding of aluminum alloy.

Abstract: The texture, microstructure, plastic strain ratio r value, elongation, strain hardening index n, the value of cupping test I_E, and the correlation between r value and the other formability indices of two automotive aluminum alloys sheet 6016 and 6181, and commercial pure aluminum sheet were investigated. The results showed that the recrystallization textures of three aluminum alloys sheet are similar to each other, which mainly contain cube component. However, the r and n value, elongation, and I_E of three aluminum alloys sheet are different from each other evidently, and there is no correlation between texture and r value, and the other formability indices except the n value. The large quantity of second-phase particles in the aluminum alloy matrix has very important effect on both the r value and the formability of aluminum alloy sheet.

Abstract: In this paper, the fatigue behavior of self-piercing riveting (SPR) joints is compared with resistance spot welding (RSW) joints for the same A6063 aluminum alloy sheets. The fatigue test, where every specimen is tested under different load, is conducted on MTS810.23M testing machine, and the results show that SPR joints have superior fatigue performances. Next S-N curve of every specimen is deduced after regression analyses of test data and the fatigue damage rule of SPR aluminum alloy sheets is summarized. Finally the effect of test parameters and errors on fatigue life of RSW and SPR joints is evaluated with two-factor and multiple factor analyses of variance.

Abstract: In this paper, the technology of self-piercing riveting (SPR) with half-hollow rivets was investigated using experiments and numerical simulations with 6063 aluminum alloy sheet. The failure mechanism of SPR aluminum alloy sheet was indicated with the shear model and tear model, which could accurately simulate the sheet structure. Based on the simulation results with finite element method (FEA), the effect of die geometry on static mechanical characteristics, including punch load, failure load and failure displacement, was analyzed. It was discovered that the die pip height and sheet thickness should be designed synthetically for optimal tensile behavior.

Abstract: Results of an experimental investigation of effects of two advanced technologies for materials cutting, namely water-jet and electroerosive cutting, respectively, are described. Water jet cutting, with abrasive particles and specific parameters, and electroerosive cutting were applied to an aircraft Al-alloy sheet Al 2124 T851 of a considerable thickness, namely 50.8 mm. Reference batch of specimens was manufactured using fine finishing milling. Surface quality of each of the cutting and machining technologies was evaluated and fatigue strength was investigated. Three point bend fatigue tests performed at constant stress amplitude showed a considerable deterioration effect of both technologies on fatigue strength. The damaging effect of both technologies was comparable. Fractographical analysis using scanning electron microscopy (SEM) showed fatigue crack initiation in numerous surface micro-notches occurring as a result of the cutting. In addition, the crack initiation was frequently accelerated by surface or subsurface fairly large particles of intermetallic phases. This mechanism also occurred with milling specimens.

Abstract: Authors ultrasonically welded A6061 aluminum alloy sheet using two types of weld tips with the different contact face geometry, and investigated the effect of the weld tip geometry on the performance and the interface structure of welds. One type of tip has a cylindrical contact face without knurl, which is called C-tip in this study. The other type of tip has flat contact face with knurl, which is called K-tip in this study. The strength of the joints welded using C-tip was higher than that welded using K-tip and the C-tip could stably produce the higher strength joint.