ABSTRACT
In order to obtain the main and secondary factors affecting the properties of the screw steel and its correlation, this text constructed a TOPSIS (Technique for order performance by similarity to ideal solution) evaluation system based on entropy weight. First of all, three properties indexes of deformed steel bar are selected: the yield strength, tensile strength and elongation at break after breaking. Secondly, we defined a comprehensive index C which is for measuring the property of thread steel by using TOPSIS method, and then the correlation degree of various chemical elements and comprehensive index C were analyzed. According to the principle that the bigger of coefficient correlation, the greater impact, to draw a conclusion: the main elements that affect the properties of deformed steel bar are C, Ceq, Si and Cr, the secondary factors are Mn, Mo, ALT, Ni, Cu, Cr, S, P and V. Finally, the correlation between various elements was studied by means of correlation analysis, where there was a significant positive correlation between Cu and Cr.