بررسي اثر نسبت CaO/SiO2 و B2O3/TiO2در تركيب پودر قالب ريخته گري مداوم بدون فلوئور بر انتقال حرارت و ويسكوزيته آن

چكيده انگليسي :

64 Investigation the Effect of CaO SiO2 and B2O3 TiO2 Ratioes in FluorideFree Mold Fluxes of Continuous Casting on Heat Transfer and Viscosity Amir Abbas Shakeri Hossein Abad Email address AmirShakery@yahoo com Date of Submission 10 14 2011 Department of Material Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor s Name Hossein Edris H Edris@cc iut ac irAbstractMould fluxes use in continuous casting Mould fluxes are added to the top of continuous casting mould inorder to cover the liquid steel and prevent thermal loss and reoxidation of liquid steel and to absorb floatedliquid solid inclusions from the liquid strand Since the molten steel is at a temperature of around 1550 C atemperature is established across the mould powder layer and the carbon in the flux starts to burn off it startssintering and then melts to form a liquid pool of flux which prevents oxidation of the steel The liquid slaginfiltrates into the gap between strand and mould aided by the mould oscillation The liquid flux partiallysolidifies leaving a slag film consisting of a solid slag layer ca 1 2 mm and a liquid layer ca 0 1 mm which provides lubrication to the newly formed shell In the continuous casting process mold fluxes have animportant influence on the surface quality of continuous casting slab Especially the surface quality dependson viscosity and heat transfer of the infiltrated mold flux between the mold wall and the solidified steel shell Generally the basic composition of mold fluxes is CaO SiO2 Al2O3 Na2O CaF2 in which fluoridemainly controls the viscosity solidification temperature and crystallization behavior of mold flux films These characteristics directly influence the lubrication and heat transfer of a mold flux Film Mould fluxesare designed to meet the requirements for specific steel grades and different steel plant conditions However in the course of its use the volatilization and acidification of fluoride poses a significant health hazard causes environmental pollution and intensifies the erosion to continuous caster In this case developing fluoride free continuous casting mold fluxes is of great significance At present theresearch on fluoride free mold fluxes is mainly concentrated on the heat transfer performance of fluoride freemold fluxes and there has been little research on viscosity characteristics done of fluoride free mold fluxes The present work adopted TiO2 to take the place of fluorine in mold fluxes and studies its heat transferperformance Heat flux simulation equipment was developed and the heat flux density of titanium bearingmold fluxes containing TiO2 was measured in addition a solid slag film was obtained The crystallizationbehavior was analyzed In this thesis an attempt has been made to prepare mold powder using TiO2 and B2O3instead of CaF2 and investigate the influence of basicity amount of TiO2 and B2O3 on the viscosity and heattransfer of the samples For this reason the different composition of fluoride free mold fluxes wasconstructed By means an apparatus that had been made for measuring heat flux of samples based on thewater cooled mold copper was constructed Also a viscosity characteristic of the samples was analyzed Aswell as micro structure of the formed slags during the experiments was analyzed And the relationshipbetween micro structures and heat transfer was investigated Key worlds Continuous Casting Mold Powder Mold Flux Fluoride Free

شاكري حسين آباد، امير عباس

بررسي اثر نسبت CaO/SiO2 و B2O3/TiO2در تركيب پودر قالب ريخته گري مداوم بدون فلوئور بر انتقال حرارت و ويسكوزيته آن

فلاكس قالب , انتقال حرارت