Formability Of Aluminum Sheet Research Articles

Microstructure and corrosion resistance of commercial purity aluminum sheet manufactured by continuous casting direct rolling after ultrasonic melt pre-treatment

During the new continuous casting direct rolling (CCDR) process for manufacturing commercially pure aluminum sheet for foils, casting defects tend to arise as the raw material with huge mass flow rapidly solidifies under a high cooling rate, which generates negative effects on the formability of aluminum sheets and the performance of final foil products. Therefore, melt pre-treatment during continuous casting is very essential to improve the quality of the billet. In this study, multi-source ultrasonic field was employed to pretreat an Al melt during the continuous casting stage in a Hazelett CCDR strip production line. The Ti content distribution in the melt, the microstructure and corrosion behaviors of the rolled sheet with and without ultrasonic melt pre-treatment (UMPT) were investigated. The microstructure of the rolled sheet was refined due to the increased Ti content and uniformly distributed Al3Ti particles under UMPT. In addition, the morphology of the Fe-containing secondary phase was modified from an aggregated to a scattered structure, with reduced continuity. As a result, under the combined effects of the refined α-Al grains and secondary phase, the corrosion resistance of the rolled sheet was improved. The underlying mechanisms for the modifications of the microstructure and corrosion resistance after UMPT are also interpreted, which gives theoretical guidance on the practical applications of the ultrasound-assisted continuous casting in industrial production.

Finite Element Simulation of Deep Drawing of Aluminium Alloy Sheets

More and more automobile companies are going for weight reduction of their vehicles for fuel economy and pollution control. The objective of the present study is to determine the effect of blank temperature on forming behaviour of sheets and damage factor of aluminium sheet alloys of 6061 and 7075 at elevated temperatures. Although the aluminium alloys have high-strength to weight ratio and good corrosion resistance, the low formability of aluminium sheets limits their use in some products with complex shapes, such as automotive body parts. The elevated forming process is intended to overcome this problem. An insight into such a study will throw light on the different temperatures required by the above materials when they are made into TWBs. Using ANSYS a series of simulations were carried out in the present investigation on the formability behaviour of deep drawing of aluminium alloys in the temperature range 200-500°C.

A numerical simulation of thermodynamic processes for cryogenic metal forming of aluminum sheets and comparison with experimental results

Forming at cryogenic temperatures provides a significant improvement in formability of aluminum sheets. This offers the potential for light, complex and highly integrated one-piece components to be produced out of aluminum alloys at sub-zero temperatures. This would allow weight reduction, environmental conservation and cost reduction of a car body to give one example in the automotive industry. For temperature supported processes special forming tools and cooling strategies are required to be able to reach and maintain process stability. Time dependent numerical simulations of the thermodynamic processes of cryogenic sheet metal forming covering all aspects of heat transfer through conduction, convection and radiation play a vital role in the design and development of future tools and are presented for several geometries. Cooling (and heating) strategies (including selection of the number of cooling loops and their relative positioning) in a Nakajima testing tool were evaluated using computational fluid dynamics. These simulations were performed with static and transient solvers to demonstrate the extraction of tool surface temperature distributions on different forming tool geometries. Comparisons of predicted temperature characteristics of an aluminum sheet and experimentally determined temperature distributions were made. The temperature distribution of the surface of an aluminum sheet could be predicted with high accuracy. Further, the influence of the tool size on the parameters temperature transfer times and temperature homogeneity was examined by introducing a scaling factor of the forming tool. It became evident, that the size ratio between the aluminum sheet thickness and the tool contact area has a major influence on these parameters. Finally, further simulations were carried out using a forming tool for representative shaped car body components to show the effects of multiple cooling loops and different cooling strategies.

Numerical and experimental investigations of hydro-mechanical deep drawing process of laminated aluminum/steel sheets

The application of hydro-mechanical deep drawing (HMDD) process on laminated sheets combines advantages of both process and material to improve the forming condition of poor formable light-weight metals such as aluminum alloys. In this research, the HMDD process of anisotropic laminated bimetallic sheets has been analyzed using a 3D finite element simulation with implementing Fortran based code for accurate modeling of non-uniform oil pressure distribution. To verify FE results, experimental works were conducted on the widely used laminated aluminum/steel sheets. Based on the developed FE model, parametric studies were performed to investigate the effect of material parameters such as layers thickness and lay-up arrangement on the forming condition, process window and formability of aluminum sheet as key process parameters. Results demonstrated that suitable process condition to attain a successful forming of bimetallic aluminum/steel sheets can be predicted by developed FE model reasonably. Also, It shown that wider working zone was achievable with decrease in drawing ratio, reduction in thickness of sheet with lower strength layer and also when aluminum sheet is in contact with punch (A/S lay-up). In addition, the higher limiting drawing ratio (LDR) and lower thinning in low formable aluminum sheet would be achievable in A/S lay-up than S/A lay-up.

Fuel cap stamping simulation of AA5754 sheets using a microstructure based macro-micro multi-scale approach

Abstracts A macro–micro multi-scale approach is applied to study the fuel-cap forming process to identify the effects of friction, material constitutive behavior and microstructural features on formability of aluminum sheets. In the sample level (macro-scale) model, lower friction at contacts between blank and dies/post are found to delay the onset of necking. This is due to the fact that the materials from the center and outer regions are less hindered by frictional force to flow to the regions of most severe deformation. High work hardening index and strain rate sensitivity are seen to effectively delay necking and enhance the fuel cap stamp formability. Particle distributions in the microstructurally-based sub-model are shown to play a weak role in pre-necking deformation, and have a large influence on post-necking deformation. The post-necking through-thickness thinning process, however, is very fast and makes a minor contribution to the total formability from initial deformation to final fracture, suggesting that continuous cast aluminum sheets with particle stringers may be used for stamping fuel cap component as efficiently as the direct chill cast aluminum sheets which a more homogeneous particle distribution.

Effect of Zr Addition on Microstructure and Warm Formability of Al-Mg Sheet Alloys

The trace element Zr was added to an Al-Mg alloy to investigate its effects on microstructure and warm formability of aluminium sheets. Microstructural examination showed that the Zr addition resulted in an elongated grain structure due to inhibitedrecovery and recrystallization by Al3Zr particles during thermomechanical treatments. In order to evaluate the warm formability, warm tensile tests were carried out at temperatures ranging from 275 to 350°C, and at strain rates ranging from 0.015 to 1.5 s-1. The results showed that the addition of Zr increased the flow stress but decreased the ductility at most test conditions. At a low strain rate of 0.015 s-1, the addition of Zr resulted in low ductility at 350°C but high ductility at 275°C.The effect of Zr additions on warm formability is discussed on the basis of the microstructural changes.

자동차 바디용 알루미늄 판재의 성형성

자동차 바디용 알루미늄 판재의 성형성

The low temperature precipitation in commercial-purity aluminium sheets for foils

The solid solubility of elements Fe and Si in aluminium matrix, and the amount of precipitation of intermetallic compounds bearing Fe and Si from the matrix are crucial microstructural parameters, which are found to have marked effects on the formability of aluminium sheets and the mechanical properties of final foil products. The low temperature precipitation in commercial-purity aluminium sheets for foils was investigated by XRD, TEM, optical microscopy, and quantitative metallography. A method was proposed to quantify the precipitation fraction and solid solubility from matrix lattice parameter based on X-ray diffraction analysis. The results showed that the fine rod-like phase, β-FeSiAl 5, with average size of about 0.2 μm, precipitates out from the Al matrix during low temperature additional annealing. The precipitation of β-FeSiAl 5 was found to lead to an increase in the lattice constant of the Al matrix. Annealing at 210 °C is favourable to the precipitation of the compound containing Si and Fe from the matrix. After 15 h annealing at 210 °C, the solid solubility of Si is reduced by about 50%. Appropriate pre-anneal deformation promotes the precipitation and helps microstructure improvement.

The formability of aluminum sheet in incremental forming

In incremental forming, the sheet exhibits a unique pattern of the forming limit curve. In the present investigation, a forming tool containing a freely rotating ball was developed and used to characterize the formability of fully annealed Al 1050 sheet. Various strain paths were applied to the sheet by imposing different tool paths and the major and minor strains of deformed grids around cracks were measured. It was found that the formability of the sheet shows a distinct dependence on the strain path and appears as a straight line in the forming limit diagram. The most suitable forming limit curve for incremental forming was found to be the one that was obtained from a test in which straight paths, with an incremental increase of tool depth, were imposed using a square specimen with the fixed periphery.

Formability of Aluminium Sheets in Pulsatory Straining

Formability of Aluminium Sheets in Pulsatory Straining

Texture and Formability of Aluminum Sheets

Texture and Formability of Aluminum Sheets

Improvement of press formability of aluminium sheets

Abstract The effects of cold reduction before annealing and final annealing conditions on the r and n values, press formability, and textures of commercially pure aluminium sheets and the correlation among these properties have been investigated. Cold reduction before annealing strongly affects r values of fully recrystallized sheets: r 45 and r markedly increased with increasing cold reduction (> 90%), and the order of r value with test direction changed owing to recrystallization. Two regions can be distinguished: in the first (50 to about 84% reduction), the order of r value is changed from r 45> r 90>r 0 to r 90 r 0 r 45, whereas in the second (reductions >90%),r 45 >r 90 >r 0 is changed to r 45 > r 0≳r 90. For sheets cold rolled to 90% and larger reductions, r 45 and r show high peak values, and good drawability is gained at partial recrystallization. The variation in r value with increasing annealing temperature and its variation with cold reduction before annealing can be qualitatively correlated w...

Test for sheet-metal formability with coupon and circular specimens

Formability in sheet metal is defined as the locus of the limiting strain. The initiation of localized thinning, which manifests itself as a groove, is taken as the criterion of failure. The deformation of circular and coupon specimens is discussed with particular reference to the effect of the process parameters on the strain ratios at the critical section. Curves are presented for the formability of aluminum sheets with failure in both the direction of rolling and that perpendicular to it.

The Effects of Processing Variables on the Formability of Aluminium Sheets : 2nd Report, The Effect of Annealing Temperature

The Effects of Processing Variables on the Formability of Aluminium Sheets : 2nd Report, The Effect of Annealing Temperature

The Effects of Processing Variables on Formability of Aluminium Sheets : 1st Report, The Effect of Cold Reduction

This investigation aims to clarify the optimum processing conditions of a commercially pure aluminium sheet for press-formability, in correlation with the tensile properties and the crystallographic orientation. The process variables dealt with are the cold reduction and the annealing temperature after hot working. In the first report, the effects of the cold reduction are examined in as-rolled conditions. Plastic strain ratio γ of the tensile specimens taken at 45° and 90° to rolling direction shows the maximum in the 80% cold-reduced sheet. But, the γ-value at 0° to rolling direction decreases monotonously with an increasing cold reduction and is the least among those three directions at any amounts of cold reduction. From observation of the location where a fracture initiates during drawing, it is confirmed that the drawability is governed by the minimum γ-value in planar directions. As the cold reduction increases, the stretch-formability always lowers, but the drawability does not always lower. The former is well correlated with the variation of the n-value obtained from a bulge test and the latter is correlated with that of the minimum γ-value.

The Effects of Processing Variables on the Formability of Aluminium Sheets : 1st Report, The Effect of Cold Reduction

The Effects of Processing Variables on the Formability of Aluminium Sheets : 1st Report, The Effect of Cold Reduction

The Effects of Processing Variables on Formability of Aluminium Sheets : 2nd Report, The Effect of Annealing Temperature

The optimum processing conditions of commercially pure aluminium sheet for the pressformability are clarified in correlation with the tensile properties, crystallographic orientation and microscopic structure, by testing sheets differently cold-reduced and annealed at various temperatures. It is concluded that the drawability is governed by the minimum value of r in the sheet plane, similarly to the case of the as-rolled sheets in the previous report. Therefore, the processing conditions which increase the minimum value of r are effective in improving the drawability. The r-value of the tensile specimen taken at 0° to the rolling direction is minimum in the asrolled sheets, but the r-value at 45° becomes minimum in the fully annealed sheets. The numerical order of the r-values in the three directions is in most cases reversed by annealing. The minimum value of r becomes largest at the transition point of this reversal, where recrystallized grains are partially observed. In addition, at this point, the earless condition is satisfied. The heavier the cold reduction prior to annealing the higher becomes the minimum value of r.