The Research On LF Refining Slag System For Desulphurization Of BM510L Automobile Beam Steel

At present, automobile beam steel with the tensile strength of510MPa is used inmany fields, and its yield strength is generally more than360MPa. However, the shape ofautomobile beam steel is a little complex, which not only needs relatively high yieldstrength and tensile strength, but also needs good elongation rate, cold bending propertyand deep drawing performance. Meanwhile, automobile beam steel has more strictstandards for the inclusions in it with increasing requirements on the aspects of car’sstructure weight reduction and safety. The inclusion content in automobile beam steel thenhas a more rigid standard and sulfide inclusions are the main controlled object in manykinds of inclusions. In most steel enterprises, control the content of carbon and manganeseto stay in a certain level and the grain is refined by the way of controlled rolling andcontrolled cooling. Moreover, these producing processes can never operate smoothlywithout the effective control on the content and form of the inclusions in refining process.Basing on the background above, this paper starts its research from the LF refiningprocess, which aims to provide an improved desulphurization slag system that can be theimportant link of continuous casting and contour machining for providing high qualitymolten automobile beam steel. The BaO that used in the improved slag system has astronger alkalinity than CaO. Proper addition of BaO can have the effects of improvingsulfur capacity and sulfur partition ratio, which is very useful to the accomplishment ofquick desulphurization process of molten steel.In the improved experiment of desulphurization slag system, it uses the quadraticorthogonal regression method, CaO-A12O3-MgO-CaF2-SiO2five kinds of compound slagseries of basic slag system. Finally, through analysis and discussion of the relationship, aprimary refining slag composition range of BM510L beam steel desulphurization effect isobtained: Range of BaO content is10%~12%, the ratio range for CaO/Al2O3is2.25~2.75, range of SiO2content is10%~12%, CaF2content is5%, MgO content is5%.