Papers by Keyword: Hot Rolling

Abstract: The use of wrought magnesium for automobile structural components is an important component of the mass reduction strategy for automobiles to improve their fuel efficiency. Compared to Direct chill casting, Twin Roll Casting (TRC) allows major reduction of hot rolling steps in the production of Mg sheet due to the thin thickness of the as-cast strip. This TRC route can substantially reduce the time and cost to produce Mg alloy sheet product. In this work, AZ31 magnesium alloy was casted to 5 and 6 mm thick strips under different process conditions. Microstructure of these strips was analyzed using optical microscopy, SEM and EPMA. TRC strip was annealed under two different conditions: 2 hours at 330 and 1 hour at 400°C. It has been found that heat treatment at 400°C for 1 hour reduces centerline segregation significantly. TRC strips were rolled down to 2 mm and annealed at 450°C for 2 minutes. The average grain size was 4-6 µm and mechanical properties were comparable with commercial AZ31 sheet.

Abstract: In this paper, the influence of chemical compositon on the formability of γ-fibre texture, and the hot band microstrcture has been studied. Experiments have been conducted to investigate the effect of hot rolling conditions. Nb-Ti added and Nb-Ti free specimens hot rolled in differencd hot rolling conditions have been compared. The results show that, the change in band width is dependent on hot rolling tempreture. When the hot band are rolled at the temperature of 1150-950 °C, large sizes on ferrite grain are observed, and this character is presented more obviously in the specimen with no Nb-Ti. As the incresaing of the hot rolling temperature, the intensity of γ-fibre texture decreases. γ-fibre texture presented in Nb-Ti added specimen is stronger under three hot rolling conditions.

Abstract: The Plate Bending phenomenon on R1 Mill is the research object in this paper. The mechanism and the influence factors of the plate bending are studied by Marc FEM Model. The restrainable measures of the plate bending are put forward and are used in the plate rolling on R1 Mill, consequently the phenomena of the plate bending are decreased infinitely.

Abstract: This paper began with the theory of laser-distance measurement and the composition of the flatness detection system, and mainly analyzed the error of the flatness measurement system of hot rolling strip caused by the installation and studied the maximum thickness which could be allowed to measure in order to ensure the measurement precision

Abstract: Mill is always weighed by its longitudinal stiffness. The prediction precision of longitudinal stiffness related strip geometric accuracy. Taking 1700mm hot strip line as research object, stiffness of housing, bearing wall and roll was calculated by finite elements method(FEM), hydraulic system stiffness was obtained by theoretical formula. Analyzing vertical system and structural symmetry of mill, functional relationship between longitudinal stiffness and its components stiffness was derived according to series or parallel connection with various components. Longitudinal stiffness was the basis on thickness set-up model. Calculation result was verified by practical test.

Abstract: According to the hot rolling technological requirements on the bearing-steel-ball blanks, an automated conveying system program was proposed. The primary structure and the characteristic of this automatic conveying system was introduced as well as the working principle of it. It was found that the system possessed the advantages such as higher feeding accuracy, good job stability and rational construction and it can meet the process requirements.

Abstract: This paper investigated the microstructures and compressive properties of hot-rolled Mg-Zr-Ca alloys for biomedical applications. The microstructures of the Mg-Zr-Ca alloys were examined by X-ray diffraction analysis and optical microscopy, and the compressive properties were determined from compressive tests. The experimental results indicate that the hot-rolled Mg-Zr-Ca alloys with 1% Ca are composed of one single a phase and those alloys with 2% Ca consist of both Mg₂Ca and a phase. The hot-rolled Mg-Zr-Ca alloys exhibit typical elongated microstructures with obvious fibrous stripe, and have much higher compressive strength and lower compressive modulus than pure Mg. All the studied alloys have much higher compressive yield strength than the human bone (90~140 MPa) and comparable modulus with the human bone, suggesting that they have a great potential to be good candidates for biomedical applications.

Abstract: During the hot rolling process, the perturbation of transverse asymmetry factor will generate strip steering, strip delivery wedge and other failure state. During the steady rolling stage, the constraint action of tension and so on can restrain strip steering. Transverse asymmetry characteristic mainly passes in the form of strip delivery wedge between the standers. Firstly this paper researches correlation of transverse asymmetry characteristic parameter toward single stander, establishes a function model to reflect transverse asymmetry result status, for instance strip delivery wedge, strip entry wedge, strip eccentric, gap wedge and other transverse asymmetry disturbance factor. Then the paper establishes transfer model of transverse asymmetry characteristic between standers, gets result status of strip delivery wedge between each ensuing standers under strip entry wedge, strip eccentric, gap wedge and other combination of disturbance. At last the paper takes working condition of actual aluminum hot rolling production line as an example, computes transfer coefficient of strip delivery wedge under several perturbation and discuss transfer discipline of transverse asymmetry characteristic between standers.

Abstract: This paper investigates the effects of normal hot rolling and high rate cooling (NHR+HRC) on microstructure and mechanical properties of the rolled EH 36 hull plate. Double-hit tests were carried out to study the effect of process parameters such as the deformation temperature and soaking time on microstructures of the tested steel, and explore optimal processing parameters. Single-hit compression with various parameters was developed and the microstructures of the tested steel are analyzed to determine the cooling rate and the final cooling temperature of the normal hot rolling and high rate cooling. This study will provide experimental and theoretical base on high-temperature rolling control system. Industrial trial was performed to produce regular products. The results show that the NHR+HRC is an effective and promising method to improve the product quality of high-strength hull plate.

Abstract: An inline hot rolling was operated on 5182 aluminum alloy strip cast using a vertical type high speed caster (VHSTRC) at the speed of 60 m/min. A porosity existing at center line of the thickness and a ripple mark on the surface, these are typical defects of the strip cast by the VHSTRC, could be improved by the inline rolling. The rolling speed was as same as the roll-casting-speed of 60m/min. The temperature of the strip, when the inline rolling was operated, was 450oC. The reduction of the strip of the inline rolling was 35%.