Research Of Steelmaking Process Of Cold Heading Steel In Xinsteel

Cold heading steel is wildly used in manufacturing fastening pieces, spare parts ofautomobile, engineering, constructure, machinery and electronic etc. In order to keepstable product quality of cold heading steel, impurities contents such as sulfur andphosphorus should be keeping as low as possible; meanwhile, the contents of siliconand manganese must be kept in low level in the steelmaking process. This paperinvestigated deoxidation processing, sulfur capacity of refine slag and pick up of siliconin the cold heading steel metallurgical process.Specimens were collected from the work site and analysis by chemical mothod intesting certer of Xinsteel, experiments of molten steel deoxidized, sulfur capacity of LFrefining slag and pick up of silicon in molten steel were conducted combined withrelated thermodynamic model.The results as follow:(1) The capability of deoxidation of manganese is increasing alone with thedecrease of temperature, especially at certain low temperature. The deoxidizing capacityof0.4%manganese equals to0.5%manganese between1540℃-1560℃.0.8%manganese in1600℃equals to0.4%manganese in1540℃,which corresponding to thecontents of oxygen in molten steel was0.065%,0.067%, respectively. Aluminumdeoxidizing ability is strong in [%Al]＜0.01and deoxidation curve changes obvious.The contents of oxygen of molten steel is decreasing with the increasing of aluminumcontents in molter steel in1600℃. When the contents of aluminum in molten steel ismore than0.05%,however,the contents of oxygen in molten steel changes little with theincreasing of aluminum contents.(2) Sulfur capacity varies with the changing of quaternary basicity. As for binary basicity, it did not show any rule with sulfur capacity.it is can be ignore of MgO impacton sulfur capacity. Effect of main elements in refining lag on sulfur capacity is calcia,silica and alumina from the point of view of composition of refining slag basicity.Sulfur capacity is increasing with the decreasing of alumina contents in refining slag incertain range of contents of calcia and silica.it has inverse relation between sulfurcapacity and alumina in certain value of CaO/SiO2. The optimum binary basicity is4-5and corresponding Cs is0.15.(3) The phenomena of pick up of silicon between molten steel and slag is go onuntil comes to a new equilibrium after five minute of LF melting slag.when compositionof refining slag is constant and the contents of silicon and aluminum in molten steelcomes to0.45%,0.04-0.05%, respectively, the pick up of silicon can not happen aftertwenty minute of melting slag, as well as smelting end.