UPAYA PENCEGAHAN TERBENTUKNYA INKLUSI SILIKAT FASA PADAT PADA PERMUKAAN BILET BAJA KARBON RENDAH

The mechanical properties ofsteel billets, slabs orblooms are controlled by the chemical composition and by the treatment and/or mechanical treatment to which the steel is submitted. However, structural defects, such as non-metallic inclusions, are also responsible for theperformance ofthis material when it is submitted to mechanical stress. The problem in clean steel manufacture is to reduce the overall numbers of inclusions andtheir size distribution. By controlling the amount, distribution, size andchemical composition ofnon-metallic inclusions, it is possible to get clean steel with good quality. The identification ofthe nature and the control of inclusionformation inliquid steel are very importantfor steelcleans. The main purpose of ladlefurnacetreatment is to ensure that themolten steel has therequired temperature when theladle is taken over at downstream secondary metallurgy units or at a continuous caster. Besides the temperature of the melt, thesteel analysis is also calculated on-line, basedon the influences ofalloying element additions and desulphurisation. Minimization of the number of solid silicate inclusions must take place after deoxidant addition andbefore pouring into the CCM. A ladle furnace is used to relieve the primary melter of most secondary refining operations, and its primaryfunctions are "reheating of liquid steel through electric power conducted by graphite electrodes., homogenization of liquid steel temperature and chemistry through inert gas stirring, andformation of a slag layer that protects refractory from arc damage, consentrates and transfers heat to the liquid steel, trap non-metallic and metallic inclusions, and provide the means for desulphurization ". Normal stirring operatios are performed by percolating argon gas through a purge plug arrangement in the bottom of the ladle. In this present work, a study of chemical composition, the solid silicate inclusions has been carried out in 1041.84 ton liquid low carbon steel Grade 1015 collected in steelplant, duringthestages ofsecondaryrefinement ofsuchsteel.