【正文】 ents. Based on the principle of maintaining the accuracy of experiment results, the use of orthogonal arrays can considerably reduce the time required to perform the experiments, and increases the reproducibility of the experiment results. This method can also be employed to optimize the process parameters. Therefore, orthogonal arrays are applied herein to perform experimental planning. . Experimental planning method The Taguchi method uses the signaltonoise ratio (S/N) as a quality benchmark, 關(guān)于工藝參數(shù)對熱擠壓鎂合金影響的研究 3 based on the ideal function, different measures are used for the various quality properties. S/N ratios are one of the three forms – the normalthebest, the smallerthebetter and the largerthebetter. The mechanical property discussed herein is tensile strength. It is the largerthebetter characteristic. Therefore, an S/N ratio that is the largerthebetter is used, and is given in Eq. (1). (1) in the equation, n stands the total number of measurements, and yi the measured quality value. The i in the suffix refers to the number of the experiment in the plan based on orthogonal arrays, and the calculated S/N ratio is used in the factor response statistical analysis, and the optimal bination of process parameters can be obtained. . Application of analysis of variance The statistical analysis of variance (ANOVA), used in the Taguchi method, is adopted mainly to evaluate the significance level of experimental errors and every factor response. The equations used in the ANOVA statistical analysis in this study are as follows. (1) Sum of squares of the factor effect vector, SSfactor (2) where n is the number of times the experiment is performed, r is the number of times the experiment is repeated, L is the number of factor levels, yk is the response value of that factor at level k, and ym is the average of all experimental data. (2) Sum of squares of the total variation vector, SStotal (3) where yij stands for the j experiment data of the its set of experiment. (3) Error sums of squares, SSe SSe = SStotal – SSfactor (4) (4) Degree of freedom of the factor effect vector, DOFfactor DOFfactor = L ? 1 (5) (5) Degree of freedom of the total variation vector noises, DOfactor DOfactor = n r ? 1 (6) (6) Variance of the factor, Vi iii DOFSSV? (7) (7) Distribution of the predicted values of the two variances, F Verrorfactorfactor VF ? (8) 關(guān)于工藝參數(shù)對熱擠壓鎂合金影響的研究 4 where Verror stands for the variance caused by errors. (8) Contribution, σi (9) (9) Experimental error, S (10) 3. Experimental planning This study involves (1) the hot extrusion process, in which the tubes are analyzed by the Taguchi method, and the optimal bination of process parameters for a best mechanical properties can be obtained。C was firstly employedfor rolling, which was followed by forging. As the temperature increased over 300176。 Magnesium alloy。 2020 Elsevier . All rights reserved. Keywords: Hot extrusion tube。 Orthogonal array 1. Introduction Magnesium alloy has low specific gravity, high specific strength, good ventilation and shock absorption. It is also opaque to electromagic waves and recycle. In recent years, magnesium alloy has begun to replace steel, aluminum and plastic as products have bee increasingly miniaturized. Magnesium alloy is 35% and 77% less dense than aluminum alloy and steel, respectively. Therefore, as lightweight products, environmental protection and recyclability bee increasingly important, the demand for magnesium alloy has increased and been extensively applied to the automobile industry, the bicycle industry, the aerospace and national defense industries, the civic product manufacturing industry and the 3C (puter, munication and consumer electronic) electronic industry. At present, die casting is the main method for forming and processing magnesium and Chang used the Taguchi method in the die casting of magnesium alloy to produce a cover for a personal data assistant (PDA), and thus to identify the optimal process parameters. Takudaetal adopted the finite element method to analyze the formability of AZ31 magnesium base material during deep drawing. Finite 關(guān)于工藝參數(shù)對熱擠壓鎂合金影響的研究 2 element analysis can be used to predict cracking position, which can then be verified experimentally. Chen et an AZ31 magnesium alloy sheet to study the deep drawing of a square cup. Following deep drawing at room temperature, the final sheet had defects, but at over 200 ?C, the formability is improved. In a related study of magnesium alloy, the microstructure of AZ31 magnesium alloy during hot high temperature of 300–450176。 (3) fullfactorial experiments。 and (4) the use of ANOVA to analyze the degree of influence of th