Refining The Tire Cord Steel, Non-metallic Inclusion Morphology

Steel cord is a kind of clean steel which quality depends on the qualities of the rod provided and the wire with a diameter of 0.15-0.38mm after pulling-out. Thus the requirements for size and shape and deformation of the inclusions in steel cord surface are very stringent, nitrogen content in steel should be as low as possible. Also the residual elements in the steel and internal and surface defects of the billet shoulde be stricktly controlled.This article describes the production status and the development trends of steel cord at home and abroad. Smelting technology for steel cord, optimization of refining slag, modification and removal for inclusions are discussed in accordance with the quality requirements of the production process and refining slag research. Some suggestions for production of high quality and high value-added steel cord are proposed combined the current high-carbon steel production conditions at Panzhihua Iron and Steel Co. with other domestic manufacturers.The components of refining slags are chosen based on the requests for inclusions referred to ternary system phase diagrams and the inclusion requirements. Combined the known equilibrium state diagram and the structure of the basic law of slag with previous research findings and technological requirements. Designed the refining slag which basic component to CaO,SiO2,Al2O3 and MgO,CaF2 additives. According to different ratio of raw materials for the refining of molten slag and steel temperature measurement balance test, analyzed and discussed refining slag basicity and components of the refining slag and steel melting temperature of inclusions morphology in the same Si,Mn deoxidization conditions. Through the steel slag balance test we can found that the refining slag not only has the residue of fast-spreading characteristics of a good, but test results showed that:the inclusion of Al2O3 content increased with the basic steel Als. To control the content of Al2O3 inclusion in the plastic deformation in the region, the best steel Als should be less than 6x10-6.Through the test results available, Als can be controlled by the basicity of refining slag in liquid steel. When the basicity of refining slag is in the range of 0.8 to 1.2 and Al2O3 content can be controlled in less than 10%, you can make the Als less than 6 x 10-6 in liquid steel. In addition, the content of Al2O3 in inclusion increases with the content of Al2O3 in refining slag. And then, with the increase of basicity in refining slag, the range of Al2O3 content in inclusion increases with the content of Al2O3 in refining slag is larger. From the point of generating plastic inclusions, the basicity of refining slag should be controlled at 0.8 to 1.0.Analysis results of the test, in conditions of low alkalinity, controlling the content of Als in liquid steel and Al2O3 of inclusion is feasible through Si, Mn deoxidization and adjust Al2O3 content in refining slag. It can make the inclusion in the region of plastic. Under the condition of test, inclusion deformation ability is well. The best composition of refining slag with relatively low melting temperature is:wCaO/wSiO2:0.8-1.0,0%-10%Al2O3,8%MgO,5%CaF2.