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Axisymmetric compression tests using Gleeble 3800 simulator were carried out to investigate hot deformation behaviors of an AA5083 alloy under high strain rate conditions. Sharp temperature rise and load cell ringing characterized by severely vibrational load responses were encountered at strain rates higher than 20 s-1 and sample buckling occurred at low temperatures. The load cell ringing was corrected using a moving average method with a two-way filtering operation to correct phase distortion. Isothermal flow curves were obtained by fitting the instantaneous temperatures into a binomial function, while buckling was correlated with sample height and Young’s modulus. After the corrections, hyperbolic sine equation was successfully used to extend from the hot tensile data having strain rates lower than 3 s-1 to 100 s-1. Quantitative analyses were accordingly made over the effects of temperature, strain rate and work hardening behavior on the flow curves. The previous constitutive equation in form of temperature, strain and strain rate was modified to predict the hot deformation resistance of the AA5083 alloy at temperatures of 250-450oC under the high strain rate operations.

In this paper, we propose an innovative method for measuring the thickness, flatness, and Abbe angle of a disc. This innovative method includes three laser distance meters and one standard plate. In general, the three laser distance meters are used to determine the thickness and flatness of a disc. The Abbe angle is determined using the laser distance meter and reference plate. Our analytical results show that the proposed method can be used to obtain the precise thickness and flatness of a disc. The resolution of the measurement method is 1 μm. The flatness is measured by the least squares method. The front and back laser distance meters simultaneously measure the warp and wrinkle. The maximum deviation of the measured thickness of a disc is reduced by using two laser distance meters to determine the effects of warp and wrinkle. The thickness, flatness, warp, and wrinkle of a disc are measured quickly and conveniently.

In the hot rolling process, the steel slab may experience a temperature gradient along its transverse direction which may cause camber and wedge after rolling. Camber and wedge phenomenon will affect the quality of the steel plate. To eliminate camber and wedge phenomenon, a pair of side guides is placed before and behind the hot rolling mill. The position mode and the force mode are the control modes for side guides to correct the slab shape and to guide the slab to follow rolling direction. Finite element analysis using ABAQUS was applied to simulate hot rolling process to find the correction mechanism of rolling equipment. The centerline of slab was traced and the shape of slab was predicted. The difference of rolling load between work side and drive side of roller was determined. Furthermore, the load, stress and velocity distribution on the slab at roll bite were analyzed. By using numerical model, hot rolling parameters including side guide control strategy can be predicted, which can provide the hot rolling line as a guideline to improve the quality of the steel slab.