Theoretical Analyses and Experimental Inspections for Surface Topographs and Optical Properties of Metal Material after Cold Rolling

  • 馬 莫

Student thesis: Master's Thesis


Cold rollings for the Al5182 aluminum alloy and CQ steel strips are carried out for the purpose of improving the reflected illuminance parameters and the reflection uniformity due to the uses of lubricants and the changes in operating conditions A three-dimensional (3D) fractal model is developed through the extension of the two-dimensional (2D) Weierstrass-Mandelbrot (W-M) model for the morphologies of rolled and roller surfaces A numerical scheme is developed in this in this study for the morphologies of roller and rolled surfaces in order to determine the solutions of the periodic lengths Lx and Ly and fractal dimensions Dx and Dy in the x and y directions which are the parameters existing in the 3D W-M fractal model This 3D fractal model in combination with the “TracePro” software is able to have the reflection light tracking simulations for the rolled surfaces with different deflection angles (θ) after rolling The simulational reflection distribution fraction (RDF) for an incident angle of 20? is obtained for Al 5182 to compare with that shown in the experimental one in order to prove the trustworthiness of this 3D fractal model For Al 51825 an increase in θ of rolled specimen can reduce Dx and Dy slightly but increase Lx and Ly significantly; an increase in either Dx and Dy can elevate the maximum illuminance ((IL)max) but lower the minimum illuminance ((IL)min); the illuminance uniformity is reduced by increasing either Dx and Dy to be sufficiently large; Lx and Ly created in the specimens with a relatively smaller θ are shorter than those formed in the specimens with a relatively large θ; (IL)max is a value determined to be dependent on the θ value; however (IL)min is always lowered by increasing either Lx or Ly irrespective of the θ value; Increasing Dx Dy Lx and Ly can result in a reduction of the illuminance uniformity (Un); a specimen with a relatively larger θ can result in a higher uniformity; increasing the ((IL)max–(IL)min) value in the specimens with a small θ may result in a reduction of illuminance uniformity; increment in either of Lx Ly or decline in either of Dx Dy can increase the glossiness For CQ steel an increase in reduction ratio or fractal parameters Dx Dy Lx and Ly of roller surface can result in higher Dx Dy Lx and Ly values of rolled surfaces; decrease in Hersey number causes a minor decrease in Lx and Ly but increases the Dx and Dy values of specimens; an increase in the Dx Dy or a decrease in Lx Ly can raise the (IL)max and lower the (IL)min of specimens; Un can be elevated by either decreasing Dx Dy or increasing Lx Ly of specimens; Un can be reduced by increasing the (IL)max or decreasing (IL)min; an increase in the reduction ratio of specimen causes a decrease in ferrite intensity and increase the austenite and cementite intensity which causes an increase in hardness (HRB) of rolled specimens However no significant correlation was found between reduction ratio and Young's modulus
Date of Award2018 Dec 10
Original languageEnglish
SupervisorJen-Fin Lin (Supervisor)

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