Cold-rolled Aluminium Research Articles

Effects of Rolling Texture upon the Cutting Mechanism of the Cold-rolled Material

In order to study the effect of rolling texture on the cutting mechanism, cold-rolled aluminum alloy and brass plates which have distinctive preferred orientations were used as materials to be cut. Orthogonal cutting was performed by changing the angle e between the rolling direction and the cutting direction, and change in cutting phenomenon with θ was examined. Moreover, the obtained experimental results were analyzed by r-value and the anisotropic parameters which were determined from tensile tests of the same plates. The results showed that the effects of plastic anisotropy of the material appeared clearly at the cutting force, that is, cutting shear stress τs was affected by the harmonic mean value r in shearing direction.

Influence of strain rate and temperature on brittle-ductile transition of cold rolled Al - 0.26% Ti after Ga liquid absorption at 50°C

The results presented here show that the transitory brittle period of the gallium-penetrated cold-rolled aluminium specimens depends on the imposed strain rate. At lower strain rates, the gallium-penetrated specimens tested at 50°C become ductile after a shorter holding at this temperature. The duration of the transitory brittle period can be reduced by a prior tensile deformation at a lower strain rate as observed in the case of the specimens impregnated with 3% gallium at 50°C. The mechanism by which the combined action of stresses and deformations reduces the brittle-ductile transition period for a higher strain rate deformation is not yet elucidated. Further, when the tensile is carried out at 0°C, i.e. far below the eutectic temperature, the specimens show a ductile behaviour and the total fracture strains are important compared to the initial 85 % cold rolled aluminium. The increase in the ductility of cold rolled aluminium, observed at 0°C immediately following the gallium absorption has not been reported and explained so far. Detailed microstructural investigations would be needed to explain this phenomenon. The increase in ductility at 0°C after gallium penetration at 50°C has not been observed in the case of annealed specimens and as such this phenomenon is reserved only to cold rolled specimens.

Hailstone Size Inferred from Dents in Cold-Rolled Aluminum Sheet

The reflecting properties of microscopic corrugations on the surface of cold-rolled aluminum sheet used in hailpads led to a new technique for determining the size of hailstones. Hailstone models of various shapes and sizes were used to produce dents in the sheet, for normal and oblique impacts. It was found that ϕ, the diameter (or equivalent spherical diameter) of hailstones, was related to d, the diameter of the characteristic shadow inside dents, such that ϕ = 0.6d + 3 (for 4 ≤ ϕ ≤ 40 mm). The standard deviation of ϕ (for normal impacts) was found to be ±8% for spheres of ϕ = 6 mm, ±5% for spheres of ϕ ≥ 11 mm and between approximately ±6 and ±17% for nonspherical objects. Also, the value of d for nonspherical objects that impacted at angles of up to 50° was only about 10% larger than the corresponding value of d if the impact had been normal. An estimate of the kinetic energy of an impacting hailstone may therefore be made from d. This method proved to be particularly suitable for recording actual hailfalls and results thus obtained are discussed.

Temporary embrittlement followed by increase in ductility after gallium penetration in cold rolled aluminium

Temporary embrittlement followed by increase in ductility after gallium penetration in cold rolled aluminium

An Improvement of Rolling Stability During Cold Rolling of Aluminum

Forward slip during the rolling process is adopted as a measure in evaluating rolling stability. Forward slip during cold rolling of aluminum has a serious effect on the productivity as well as the quality of rolled sheets. The forward slip must remain within a specified range depending on the thickness of sheet if the rolling is to stay stable. Rolling speed, rolling tension, rolling oil viscosity, additives, rolling surface roughness, and roll diameter constitute an important factor for controlling forward slip during rolling. The present paper examines the effects of these factors on forward slip using both production-type and experimental rolling mills.

Comparison of rolling-mill plant designed for the steel and aluminium industries

AbstractThe design of rolling-mill plant, both in terms of mill layout and equipment design, is discussed with reference to current practice in the steel and aluminium industries. Outputs of typical mill installations, together with comparative mill data are given. Particular mention is made of the use of accelerated rolling techniques coupled with laminar-flow strip cooling in order to improve temperature control in the rolling of hot steel strip. The measurement of shape is considered to be a vital recent development, and is now an important topic, particularly in the cold rolling of aluminium but increasingly in the cold rolling of steel also. One particular design of shapemeter is described, the automatic control of shape is forecast, and alternative methods of achieving this on different mill types are discussed.

Engineering and Operation of a High-Speed Aluminum Cold Rolling Mill

This paper covers the selection and layout of the electrical equipment and factors governing the choices made for the Alcan Aluminum Corporation 8000 ft/min 4-high cold reducing mill located at Oswego, N.Y. Many of the new features of the mill are outlined, and an evaluation is made of their effectiveness in operation. Operating experiences and operator training are also described.

Electrical Equipment for a High-Speed Aluminum Rolling Mill

The electrical equipment and systems for a specific aluminum cold rolling mill for attaining rolling speeds in access of 8000 ft/min are described. New systems applications in automatic guage control, main drive systems control, automatic mill preset functions, automatic sequencing, and positioning systems are also presented.

Subgrain growth on annealing of thin foils of cold-rolled aluminium

Subgrain growth on annealing of thin foils of cold-rolled aluminium

Anisotropy and the Bauschinger Effect in Cold Rolled Aluminium

The paper deals with a study of the development of anisotropy and the Bauschinger effect in cold rolled aluminium. In the first instance, the development of a yield criterion considering both of these phenomena is discussed. By following a recent development by Yoshimura, a criterion involving only two parameters, one for anisotropy and the other for the Bauschinger effect, is developed. Considering the simple homogeneous rolling deformation model of Orowan, the yield criterion is applied to the case where cold rolled metal is subsequently tested in tension and compression at various orientations.Experimental procedures are described and the method of correlating the experimental results with the yield criterion is discussed. As a result of the analysis of the experimental results, it may be concluded that the yield criterion provides satisfactory correlation with experiment. The anisotropy parameter and a Bauschinger modulus are then specified in terms of rolling strain and the order of their magnitude considered.The last part of the paper is concerned with a discussion of additional factors which have a bearing on the results obtained. In the first place, the question of inhomogeneous deformation is considered. One of the consequences, the development of residual stresses, is shown to have little effect. However, additional evidence shows that the mode of deformation exerts a considerable influence on the Bauschinger modulus. It is concluded that anisotropy is probably not greatly influenced by the details of deformation, but the manifestation of the Bauschinger effect certainly is.

The effect of thickness on the distribution of dislocations in cold-rolled aluminium

Abstract The ratio of the electrical resistivity at 293°k and 77°k has been measured as a function of thickness in the range 13 μ to 2 μ for annealed and cold-rolled super-purity aluminium. The annealed specimens show the dependence predicted by Fuchs' theory of surface scattering. The cold-rolled specimens show a deviation from Fuchs' theory which may be attributed to a loss of dislocations during thinning. The loss is estimated to be about 80%.

On the annealing of cold-rolled aluminium alloy (1)

This is a report on the annealing of cold-rolled high-purity Al-Pb alloys. By measuring the breadth of X-ray rocking curve which was diffracted from a poly-crystal, the anther observed the dislocation movement in softening, recovery and recrystallization of Al-Pb alloys. The result was that in case of cold-worked and then annealed metals of Al-Pb alloys the (220) planes rocking curve breadth did not decrease so rapidly as high-purity aluminium. The integral breadth of (222), (422) planes, sometimes registered different movements from other planes.

Nuclear magnetic resonance, stored energy, and the density of dislocations in deformed aluminium

Abstract The mean-square width of the nuclear magnetic resonance absorption line and the density of dislocations observed by electron microscopy have been measured in specimens of cold-rolled aluminium. Cold rolling has been found to increase the mean-square line width by up to 120%, and the broadening is proportional to the density of dislocations. The stored energy has been calculated from the line broadening using a simple model, and the results are in reasonable agreement with the energy measured directly. The apparent energy of a dislocation in aluminium has been found to have the surprisingly high value of 18.8 × 10−4 erg/cm, and it is suggested that the density of dislocations observed in aluminium by electron microscopy does not represent the bulk value.

On the sampling in the case of the investigation for earing in deep drawing used one way cold-rolled aluminium sheet (Continued Report)

On the sampling in the case of the investigation for earing in deep drawing used one way cold-rolled aluminium sheet (Continued Report)

Sommarî

A two-step approach is proposed to investigate the shear band formation in cold-rolled aluminum alloy sheet during plane strain tension, compression and simple shear tests. In the first step, a finite element model with only one element using Taylor type polycrystal plasticity model is applied to compute the stress-strain curve of the deformation. In the second step, a full scale mesoscopic simulation is applied for a further study of the details of the shear band development for cases with higher possibility of shear band formation as judged from the results in step 1. Systematic studies show that the hardening/softening features of stress-strain curves obtained by one-element method well agree with the extent of macroscale shear bands development in mesoscopic scale simulation: softening or flat stress-strain curves correspond to the formation of severe macroscale shear band in mesoscopic scale simulation, and the stronger the softening is, the more severe the macroscale shear band is, whereas no macroscale shear band is developed when the curves exhibit continuous and obvious hardening. Therefore, when it is needed to investigate probability and features of shear band formation in many samples or loading modes, e.g. loading along different directions, people can use the first step to efficiently estimate the possibility of macroscale shear band development for all the cases concerned, and then apply the full scale mesoscopic simulation only for those cases where stress-strain curves exhibit little hardening or softening features. Our calculations show that the computation efficiency can be substantially improved by the two-step approach.

The nature of lubrication in the cold rolling of aluminium and its alloys : J. A. Schey. J. Inst. Metals, 89 (1960) 1–6

The nature of lubrication in the cold rolling of aluminium and its alloys : J. A. Schey. J. Inst. Metals, 89 (1960) 1–6

On the sampling in the case of the investigation for earing in deep drawing used one way cold-rolled aluminium sheet

On the sampling in the case of the investigation for earing in deep drawing used one way cold-rolled aluminium sheet

Grain growth in a cold-rolled aluminium single crystal

A sigle crystal of high purity aluminium was made by means of soft mold method, which was rolled on the (110) plane and in the [112] direction. After rolling, surface layers and edges were electrolytically etched off and side of the specimen was scrubbed with emery paper to produce random artificial nucleation. Then the specimen was annealed at 350°C for 600sec. A large number of grains were formed on the scrubbed side and some of these grew across the thickness of the specimen. Orientations of grain were checked by X-ray and microscope on the scrubbed side and also on the unscrubbed side. It was observed that grains on the scrubbed side had rather equiaxial shape and random orientations. On the unscrubbed side, however, grains had elongated shape in two directions. These two directions were related to the matrix by a rotation around ‹111› axes. The fact that four of eight equivalent ‹111› rotational relationships were predominant in the grain growth, suggests that the deformed single crystal matrix is not fully symmetrical for the growth rates of recrystallized grains as in the crystallo graphic meaning. It is suggested that the growth rates of recrystallized grains would be affected by the mechanism of deformation of matrix.

訂正表

訂正表

Stress distribution and friction coefficient in cold rolling of aluminium plates

A new apparatus for measuring stress distribution and dynamic friction coefficient in cold rolling of aluminium plates was made by the authors. It consists of a small tungsten pin which is set along the radius direction of the under roll, and a wire strain gauge which changes with deformation of the small pin. The wire strain gauge is sufficiently sensitive even to a small load, as the bobbin of gauge is made of cloth-bakelite.With the apparatus a series of experiments was carried out to clarify rolling stress distribution, stick-slip and dynamic friction coefficient in cold rolling of aluminium plates.The results are as follows: Many slips exist in cold rolling of aluminium plates; generally, curves between rolling stress and angle of contact part are of bell-type, and the maximum rolling stress increases proportionally to an increase of rolling reduction ratio; and dynamic friction coefficients are calculated at the neutral point, and the coefficient increases with an increase of rolling reduction ratio, too.