Influence Of Rolling Conditions Research Articles

Influence of Rolling Conditions on Reduction of Center Segregation of Steel Ingot

Influence of Rolling Conditions on Reduction of Center Segregation of Steel Ingot

The Influence of Deformation Modes on the Structure and Properties of Al–Mg–X Powder Composites. I. The Influence of Rolling Conditions on the Mechanical Properties of Aluminum Powder Ribbons Strengthened with SiC Nanoparticles

The influence of deformation modes on the mechanical properties of metal matrix composites produced from the aluminum powder strengthened with SiC nanoparticles has been studied. Symmetric and asymmetric rolling processes were employed at room temperature. Rolling as an additional deformation processing step improves the composite structure by refining the SiC agglomerates, asymmetric rolling being a more effective deformation processing technique. This complex hardening mechanism allows the strength to be increased twofold without decrease in the elastic and ductile parameters.

Formation of roll coating in cold rolling of titanium sheets

Abstract In rolling of titanium sheets, coating is severely formed on rolls by transfer of titanium from sheet surface. It increases rolling load and deteriorates quality of sheet surface. It was reported that small reduction per pass is effective to suppress the formation. However the suppression is insufficient for industrial processes. Other suppression techniques are demanded, however, the formation mechanism has not been revealed sufficiently. In this study, the formation was reproduced on a rolling mill in a laboratory. Influences of rolling conditions and of lubrication conditions have been investigated. It is found that the roll coating develops with summation of elongated length of the sheets and that lubrication with rolling oil is effective to suppress the coating. It is supposed that roll coating is formed by direct contact between the roll and titanium surface newly exposed by rolling.

11112 マグネシウム合金板材の機械的特性向上に及ぼす圧延条件の影響

11112 マグネシウム合金板材の機械的特性向上に及ぼす圧延条件の影響

Influence of rolling conditions and aging process on mechanical properties of high manganese steels

Three laboratory cast and rolled high manganese steels with different Mn (in the range of 24–28wt%), C (in the interval of 0.2–1.2wt%) and Al (from 2.3wt% to 12wt%) contents has been investigated. Differences in chemical compositions, rolling conditions and followed by aging process at the temperature of 500°C and four different aging dwells (in the range of 6min to 60min) have led to various k-carbides precipitation. The k-carbides have been responsible for the mechanical properties. The intragranular type of nano-size has increased the strength, respectively hardness level whereas the k-carbides nucleated in the intergranular form have reached size of micrometre and in lower volume fraction have not been importantly able to increase the matrix hardness, especially in case of lower C portion. Balanced Mn, C and Al contents for optimised k-carbides precipitation have been also discussed. The materials were hot rolled to strips of 1.9mm in thickness from the heating temperature of 1100°C using the rolling mill Tandem.

Influences of Rolling Conditions on Texture and Formability of Magnesium Alloy Sheets

The AZ61 magnesium alloy was subjected to the differential speed rolling at different rolling conditions including reduction per pass, rotation speed ratio and rolling temperature, and the influences of the rolling conditions on microstructure, texture, mechanical properties and formability of the as-rolled sheets were investigated. Increasing the reduction per pass results in a more homogeneous microstructure and a relatively weaker basal texture. With increasing the rotation speed ratio, the inclination angle of basal pole toward the rolling direction increases and the stretch formability enhances correspondingly. Increasing the rolling temperature has an effect on weakening the basal texture intensity and leads to the enhancement of stretch formability.

調質圧延時の板表面創成メカニズム

Most of steel products are manufactured through rolling process. Therefore, rolling process is very important for the qualities of rolled products. In the process of rolling, the temper rolling is assumed to be very important process that gives influence on the qualities of products such as the shape and roughness. However, as there is not any reasonable theory to control the surface roughness of steel strips, it is said that actual operations depend on experience and intuition. The surface transcription in temper rolling is an important process to decide the roughness of strips surface as the industrial product. But, the influence of lubricants on the surface of rolled strips and the mechanism of surface transcription have not been understood yet. In this paper, the influence of rolling conditions, such as roll diameters, roll surface processing, lubricants and rolled materials, upon the surface transcription is investigated. As a result, it is found that such rolling conditions have important effects upon the surface transcription.

Influences of Rolling Conditions on Texture and Mechanical Properties of AZ31 Magnesium Alloy Processed by Differential Speed Rolling

It was reported that the cold and warm press formability of the magnesium alloy was improved by the application of a differential speed rolling (DSR). However, it can be considered that the microstructure and the texture of the DSR processed sheets greatly change with the rolling conditions. In this study, commercial AZ31B magnesium alloy extrusions were processed by DSR at a differential speed ratio of 1.167 and a reduction per pass of 10% or less, and the effects of the rolling temperature, the number of rolling passes and reversal of the rolling direction on texture and mechanical properties were examined. As a result, it was found that the optimal rolling temperature in terms of the workability and formability of the material was 573 K. And the elongation and formability were maximal in sheets processed by 4–6 passes of DSR. Moreover, reversing the shear direction made the microstructure more homogeneous and finer than unidirectional shear, and improved the mechanical properties and formability. This improvement was greater in samples where the shear direction was reversed once in the middle than where it was reversed for each pass.

板圧延における圧延方向に平行な表面疵の変形過程の解析

The shape change of longitudinal surface micro-defects in flat rolling was investigated using a rigid-plastic finite element analysis. Rolling of plate with V-shaped scratches or rectangle defects that are parallel to the rolling direction, was simulated assuming a generalized plane strain condition. The calculated results were verified with experiments of model material, and good agreement between both results was obtained. The influence of rolling conditions, such as reduction, friction coefficient and the position of initial defect, on the shape of existing defect after rolling was evaluated. Using the developed FEM, the evolution of seam defects was also simulated, and good agreement with experimental results were obtained. The proposed prediction method can be utilized to make defect free products in flat rolling.

板圧延における表面疵の変形に及ぼす圧延条件の影響

The shape change of surface micro-defects in plate rolling was investigated using a rigid-plastic finite element analysis. Rolling of plate with rectangular-shaped scratches or plunges, which lay perpendicular to the rolling direction, was simulated. The influence of rolling conditions, such as reduction, friction coefficient, roll diameter and pass schedule on the shape of existing defect after rolling was evaluated. From these results, the relationship between the shapes of surface defect before and after rolling was obtained, and the optimum condition to eliminate defects was discussed. The proposed prediction method of surface defect can be utilized to make defect free products in rolling and forging processes.

Influence of rolling conditions on resistance to side slip and rolling of elastic wheel

It has been established by many investigators that with a small side slip angle the braking force of an elastic wheel, unlike the traction force, can cause an increase in the lateral force compared with the force arising with the same slip angle but in conditions of pure slip. The range within which the increasing braking force is accompanied by an increase in the lateral force and, therefore, an increase in resistance to the side slip, may be very broad. Attempts have been made by several scientists to explain this anomaly. This paper represents an attempt to discover the factors behind this phenomenon more completely.

Computer aided simulation of internal porosity closing in slab and plate rolling

Behaviours of closing of the internal porosity located at the thickness center of the slab or the heavy gauge plate under rolling process are discussed analytically by using the method of limit analysis. The slab or the plate in the roll gap is divided into several zones and the kinematically admissible velocity field is formulated for each zone. The formula to calculate the total power of deformation J* is derived from those velocity fields. The criteria for initiation and completion of the porosity closing are derived from the derivatives of J*. Using the criteria, influences of rolling conditions on behaviours of the porosity closing are investigated, such as thickness reduction, friction factor, ratio of roll radius to slab or plate thickness, temperature distribution in the thickness direction and dimensions of the porosity. The calculated results show good coincidence with experimental and empirical knowledges on the porosity closing. It has become clear that the simulation method developed in this study is useful to predict the necessary rolling conditions in order to eliminate the internal porosity.

Width necking at the rougher in a hot-strip mill

The accuracy of the width of a hot strip is very important for the improvement of yield, both for the steel maker and the steel user. One of the important technical problems concerning width accuracy is securing a final hot strip with uniform width along the whole length. In the top or tail portion of a hot strip, a local contraction of width unavoidably occurs, called “width necking” or simply “necking”. The amount of necking is determined mainly by the conditions of rougher rolling in the hot-strip mill. In this paper, the mechanism of necking, the influence of rolling conditions on the amount of necking and the optimum edger-rolling pass schedule are described. The main conclusions obtained are as follows: (i) Necking originates from the uneven distribution of dog-bone height along the length of a slab and the local steep width reduction in the top portion of the slab after edger rolling, but is lessened by the formation of flare during subsequent flat rolling; (ii) the amount of necking increases with the increase of slab width and edging draft and with decrease of slab thickness; and (iii) for the minimization of the amount of necking, heavy width-drafts in the early rougher-rolling stage are preferable to heavy width-drafts in the later rougher-rolling stage.

Influence of rolling conditions on the quality of hot-rolled steel strip

Influence of rolling conditions on the quality of hot-rolled steel strip