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

Dahar, Rosfian Arsyah

MESIN
Vol 8, No 3 (2006)

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