Hot Rolled Aluminum Alloy Research Articles

Effect of Special Misorientations – Crystallographic Ordered Boundaries in Recrystallization in Aluminium Alloy of Al-Si-Mg System

The deformed and recrystallized states of surface regions of hot-rolled aluminium alloy plates of Al-Si-Mg system were investigated by the method of orientation microscopy (EBSD). In the deformed state mainly shear texture components were detected. In the recrystallized structure, there was a significant dispersion of deformation texture due to an increase in the proportion of components that were located at the edges of the deformation texture. It is shown that the crystallites, which are boundary a deformed matrix with the misorientation approximately corresponding to rotation axis <552> at an angle of 52.5°, become the nuclei of recrystallization.

Influence of large amount Zn on mechanical properties and corrosion resistance of 5083 hot rolled aluminum alloy

The influence of three kinds of alloy adding 0.3–1.8 wt% Zn on the mechanical properties and corrosion resistance of medium Mg content 4.0–4.5 wt% (5083 type) hot rolled alloy was investigated. The results showed that the addition of Zn content could further dissolve the second phases into the matrix. The hardness and tensile strength were reduced when annealing at 250 °C × 2 h. The mechanical behavior of the alloys showed a tendency that increases first and then decreases and the peak reached its maximum when 1.6 wt% Zn is added at both annealed and unannealed states. Through quantitative analysis, the improvement of mechanical properties mainly comes from dislocation strengthening and Al–Mg–Zn ternary strengthening phases. Meanwhile, with the increase of Zn content, the intergranular corrosion (IGC) of the alloy improved greatly after annealing at 250 °C × 2 h. The electrochemical corrosion potential (ECP) of the alloys increased first and then decreased.

Multiscale modelling of asymmetric rolling with an anisotropic constitutive law

A parametric study is presented, which employs a new anisotropic constitutive law in order to study the influence of anisotropic plasticity on the deformation field of the Asymmetric Rolling (ASR) process. A version of the facet method is presented, where an analytical yield function is restricted to the subspace of the stress and strain rate space relevant for 2D Finite Element Analysis (FEA), but can still accurately reproduce the plastic anisotropy of an underlying Crystal Plasticity (CP) model. The influence of anisotropy on the deformation field and corresponding texture evolution is examined in terms of the changes in texture component volume fractions and formation of texture gradients. It is found that a material with the anisotropy of a sharp cold-rolled aluminium alloy is more beneficial than that of a recrystallised hot-rolled aluminium alloy, and this influence of anisotropy suggests that Asymmetric Rolling (ASR) may be best carried out in the latest stages of cold rolling.

Alternating Current Phosphoric Acid Etching of Aluminium

Alkaline etching is a common pretreatment process for aluminium alloys before anodising or application of organic coating. Removal of the mill-finish surface layer is performed by a simple dipping process, which also gives the matt finish normally required for aesthetic appearance before conventional anodising. Major disadvantage of alkaline treatment is the surface enrichment of the alloying and trace elements more noble than the aluminium substrate by dealloying. This may reduce corrosion resistance and deteriorate the optical properties of the surface. The purpose of this work is to investigate fluoride-free acid etching for aluminium alloys as an alternative to alkaline etching to prevent or reduce heavy metal enrichment, while achieving matt appearance. Alternating current is applied to increase the rate of etching as the dissolution rate of aluminium in acid solutions is slower than in alkaline solutions. The principle is based on anodic oxidation of the heavy metal components, as well as aluminium, during the anodic cycle and removal of the corrosion products and concentration gradients by hydrogen evolution during the cathodic cycle. The materials used for this study were hot-rolled aluminium alloy AA3105 (Si 0.3%, Fe 0.6%, Cu 0.1%, Mn 0.7%, Mg 0.3%) and extrusion AA6060 (Si 0.4%, Fe 0.2%, Cu 0.01%, Mn 0.02%, Mg 0.5%). Phosphoric acid was used as the etching electrolyte. Consumption of aluminium was calculated from weight loss. Appearance was analysed visually and by gloss measurements. SEM was used to study surface microstructure and morphology. Aluminium oxidation rate increased with increasing temperature, current density, electrolyte concentration and etching time. Intermetallic Al-Mn-Fe-Si particles were selectively and rapidly removed by 1 min etching at 80⁰C. In contrast, particles were exposed and remained on the surface by alkaline etching. Matt appearance without visible defects was achieved after 10 min etching at 80⁰C. Presence of phosphorus in thin oxide film formed was determined by glow discharge optical emission spectroscopy (GD-OES). Advantages foreseen of acid-based AC pretreatment over alkaline dip processes in practice are suitability for in-line coil processing, superfluity of the desmutting step, low gloss achievable with reduced metal loss, improved corrosion resistance and adhesion properties. Acknowledgements This work was supported by Hydro Aluminium and The Research Council of Norway.

Amorphous iron nanoparticles formed on aluminum surfaces during thermomechanical treatment

Iron nanoparticles were observed on the surface of commercial purity aluminum alloys after thermomechanical treatment using a hot rolling tribo-simulator with a roll surface roughness (Ra) of 0.01µm. These nanoparticles were spherical in shape and possessed an amorphous structure. They were observed lying on the oxide layer of the alloy surface and on crack faces. Iron nanoparticles have not been previously reported on aluminum surfaces under this thermomechanical condition. The surface of the hot rolled aluminum alloy was also covered with fractured iron-rich intermetallic particles embedded into the surface and caught within cracks.

Segregation of Solute Atoms in Hot Rolled Aluminum Alloy LT24

Segregation of Solute Atoms in Hot Rolled Aluminum Alloy LT24

Earing and Anisotropy Indices of Texture Components in the Hot-Rolled 3104 Alloy

The paper describes an experimental verification of a previously proposed formula establishing the relationship between the crystallographic parameters of a rolled sheet and the anisotropy index in a hot-rolled aluminum alloy. The main texture components were identified in the hot-rolled 3104 alloy using the X-ray structure analysis. The crystallographic parameters and anisotropy indices were then calculated both for the entire workpiece and for each individual texture component. The earing level of the hot-rolled workpiece was determined using the process of cylindrical cup drawing. Cup formation was also simulated using the finite element software package PAM STAMP. The earing data obtained through t simulation were compared with experimental results. For the validation of the calculations the hot-rolled workpiece anisotropy indices were also experimentally determined.

Shear deformation and plate shape control of hot-rolled aluminium alloy thick plate prepared by asymmetric rolling process

Asymmetric rolling (ASR), as one of severe plastic deformation (SPD) methods to make ultra-fine materials with enhanced performance is mainly used to prepare foil and thin strip. The asymmetrical rolling was achieved by adjusting the diameters of the upper roll and the bottom roll and was used to prepare hot-rolled thick plate of 5182 aluminium alloy. The shear deformation and plate shape control were experimentally studied. The experimental results show that asymmetrical rolling has a significant effect on metal deformation stream and can somehow refine microstructure and improve the uniformity of microstructure and properties. The asymmetrical rolling process can also reduce the rolling force. However, bending of rolling plate often happens during asymmetrical rolling process. The factors affecting the bending were discussed.

Study on the Asymmetric Hot Rolling of Aluminium Alloy Thick Plate

The development of aviation industry demands hot rolled aluminium alloy extra thick plates. However, it is quite difficult to obtain sufficient and uniform deformation of extra thick plate by conventional hot rolling process. The asymmetric hot rolling can generate an additional shear deformation and significantly improve the equivalent strain at the centre of the plate and consequently the uniformity of the microstructure, and mechanical properties. In the present work, the asymmetric rolling (ASR) was achieved by adjusting the diameters of the upper roll and the lower roll and was used to prepare hot rolled thick plate of an aluminium alloy. The effect of the asymmetric hot rolling process on the deformation, shape control, microstructure and mechanical properties was experimentally studied. The results showed that the ASR has a significant effect on metal deformation and can somehow refine microstructure and improve the uniformity of microstructure and properties although plate bending often happens during rolling process. This paper presents these results and gives corresponding discussions.

Grain Boundary Plane Distributions in a Hot Rolled 5A06 Aluminum Alloy

To investigate the preferential distribution of grain boundary planes in a hot rolled aluminum alloy, the electron backscattered diffraction approach and five‐parameter analysis method are used to characterize the grain boundary plane distributions in a hot rolled 5A06 aluminum alloy, and the results show that the orientations of grain boundary planes are textured. Grain boundary planes favor the {111} orientation at the center of the specimen, and their population is 56% higher than that in a random distribution, whereas grain boundary planes favor the {110} orientation on the surface of the specimen, and their population is 69% higher than that in a random distribution. Moreover, this anisotropic distribution of grain boundary planes occurs at all misorientation angles. The study suggests a new understanding of the pathway to evaluate the crystallographic orientation dependent performances.

Analysis of Edge Cracks in Hot Rolled Aluminium Alloy Sheets Contained of Magnesium for Can Usage

the edge crack frequently occurs in hot rolled 5182 alloy. SEM, EDS,etc.are used to analyze the factors leading to the cracks. It is discovered that high sodium content, and coarse intermetallic phase and inclusion are the main reason for these cracks. Meanwhile, some measures are suggested to be taken to avoid this kind cracks: making sure sodium content below 3 ppm; controlling the casting process and chemical composition to avoid coarse intermetallic phase; refining the melting aluminium to eliminate inclusion; setting a suitable scalping depth.

Experiment on Hot Rolling Deformation Resistance of Aluminum Alloy and Mathematical Modeling

In order to investigate the impact factor of hot rolled aluminum alloy, a experiment was finished in a factory, to determine the effects of hot-rolled aluminum alloy plate with the system deformation resistance coefficient of the various factors and to mark the influence about the temperature to the hot rolling deformation resistance; Then, established the mathematical models of 1100,3003,5052 series hot rolled aluminum alloy plate's deformation resistance; The data calculated by the theoretical mathematical models is in good agreement the measured data. So this mathematical have the importance actual significance to actual production.

Comparative study on effects of microstructures of hot rolled and twin roll casting 1235 aluminium alloy on surface quality of aluminium foils produced

Twin roll casting is an attractive technology for producing aluminium sheets for foils. But, surface defects, such as matte defects, may occur on aluminium foils produced in this way. However, it is not the case on aluminium foils produced by traditional hot rolled process. Optical microscopy, scanning electronic microscopy, energy spectrum and transmission electronic microscopy were used to investigate the effects of the microstructures of the twin roll cast and hot rolled aluminium alloy sheet for foils on the surface defects of the foils produced. It is discovered that central segregation band and surface microsegregation band in twin roll casting aluminium sheet may result in a non-uniformly distributed secondary Al–Fe and Al–Fe–Si particles in workpieces in a lower reduction pass. These non-uniformly distributed Al–Fe and Al–Fe–Si particles and microporosities in a size of several microns generated in solidification process of twin roll casting are the main cause for the surface matte defects of the aluminium foils produced.

Cube texture in hot-rolled aluminum alloy 1050 (AA1050)—nucleation and growth behavior

The microstructure and texture evolution at different annealing temperatures were analyzed in a hot-rolled commercial purity aluminum alloy from two-dimensional electron backscattered diffraction scans. The newly recrystallized grains were found to cluster together. Recrystallized grains have cube, { 0 0 1 } 〈 1 0 0 〉 , as the dominant texture component at all annealing temperatures. Nucleation and growth behavior of the recrystallized cube grains was observed by measuring the variations in first nearest neighbor boundary pixels of these grains. The texture of nearest neighbor pixels at low fraction recrystallized represents the nucleation environment of newly recrystallized grains. Growth rates of the recrystallized grains were estimated from the variation in grain size with time at different annealing temperatures. Analysis of nucleation and growth behavior of the recrystallized cube grains reveals a significant nucleation advantage at all annealing temperatures: a decreasing growth advantage is observed as the annealing temperature is increased. Further analysis of the nucleation environment of the recrystallizing cube grains also revealed that among the main texture components of deformed grains (S, brass and copper), they grow more rapidly into the S component than into the copper or brass components. This trend persists throughout recrystallization such that the brass component is the slowest to recrystallize. In terms of the oriented nucleation (ON) and oriented growth (OG) theories, ON has a greater impact on the development of recrystallization texture than OG.

Abnormal Subgrain Growth by Monte Carlo Simulation Based on Hot-Rolled AA5005 Aluminum Alloy Texture

The subgrain structure of hot rolled aluminum alloy AA 5005 has been characterized on as-received samples using Electron Backscatter Diffraction (EBSD). Based on the OIM scans of RD-ND and TD-ND, 3 dimensional microstructures of subgrains are built up using the 3D Microstructure Builder, which is a method for developing statistically representative digital representations of microstructures. Following the generation of microstructure, different textures were fit to these reconstructed 3D microstructures, based on individual components such as Brass and S textures. For this study, the Brass texture was chosen as an exemplary case. Monte Carlo simulation was used to model subgrain coarsening and visualization was a key to detecting abnormal grain growth. The main objective is to understand the circumstances under which we can expect abnormal (sub-)grain growth to lead to nucleation of recrystallization.

Computer simulations of realistic microstructures of coarse constituent particles in a hot-rolled aluminum alloy

Computer simulations of realistic microstructures of coarse constituent particles in hot-rolled 7075 Al-alloy plate are presented. These simulations incorporate realistic complex morphologies/shapes of the constituent particles as well as their spatially clustered non-uniform arrangements and partially anisotropic morphological orientations. The methodology permits simulations of sufficiently large microstructural windows that incorporate short-range (on the order of particle/feature size) as well as long-range (few hundred times the particle/feature size) microstructural heterogeneities and spatial patterns. Two-point correlation functions are used for microstructure representation. The two-point correlation functions of the simulated microstructures are closely matched with those of the corresponding real microstructures. The simulation parameters enable simulations of virtual microstructures of the alloy that cover a range of different volume fractions and average sizes of the constituent particles.

Formation and structure of a subsurface layer in hot rolled aluminium alloy AA3104 transfer bar

As a basis for extended studies into the evolution, structure and corrosion properties of the subsurface layers in hot rolled aluminium alloys, the evolution of the subsurface layers in industrially rolled AA3104 transfer bar has been simulated in a laboratory mill. Test samples taken from the centre of industrially rolled AA3104 transfer bar were highly polished, reheated and homogenised under carefully determined conditions and rolled in the two-high Robertson mill at the University of Sheffield. The stock surfaces and subsurface layers in industrially rolled and laboratory rolled material were then characterised using a combination of optical microscopy, quantification of stock surface morphology, glow discharge optical emission spectrometry (GDOES), focussed ion beam (FIB) microscopy and filiform corrosion testing. The results from the experimental programme have demonstrated that the near-surface metallic element distributions, the microstructures and depths of the subsurface layers and the filiform corrosion susceptibility of the rolled surfaces in the industrially rolled and laboratory rolled materials were all very similar.

Application of SSNTDs for study of boron distribution in alloys

A study of boron behavior and its distribution in boron doped iron-, nickel- and aluminum-base alloys subjected to various treatment conditions has been performed. For this purpose a technique based on the detection of 10B(n,α) 7Li reaction products with track etch detectors has been applied. High boron enrichment of grain boundaries of both iron base and ingot nickel base alloys has been observed. After hot and then cold rolling of the latter specimens boron rearrangement along with the proper deformation of the structure took place. Striation of boron in a hot rolled aluminum alloy along the rolling direction has been observed.

On the Validity of Assumptions Made in Theories of Plastic Flow for Metals

Abstract The purpose of this paper is to report the results of a series of special biaxial-stress tests made to check the validity of certain assumptions used in theory of plasticity. In these tests the stresses produced were tensile biaxial stresses introduced in a tubular specimen by applying an internal pressure and axial tension. The stresses produced were in the plastic range and the material tested was a hot-rolled aluminum alloy designated as 14S-T6. A test to determine the validity of the distortion-energy criterion, used in formulating the plastic stress-strain relations by the flow theory, showed that the test results did not support this assumption. Special tests were made to determine whether plastic-deformation requirements as predicted by the slip theory were correct. In so far as these tests were concerned, the results supported the slip theory. Finally, tests were made to check the assumption of constancy of volume and constancy of incremental change in volume as required by the deformation and flow theories. These test results do not support the assumptions made in these theories relative to volume change.