Development of Mould Fluxes for Bloom Continuous Casting of High Carbon Steel
|Course||Iron and steel metallurgy|
|Keywords||Bloom continuous casting Fluxes Sintering characteristics Physical properties Mathematical model|
To ensure the Panzhihua Iron and bloom continuous casting casting U71Mn, PD3 and high carbon steel production anterograde and get a good slab quality bloom continuous casting mold fluxes of domestic and foreign research and application of research based on the Bloom the characteristics of the continuous casting high carbon steel and difficult, Panzhihua Iron and casting machine parameters and process conditions, to carry out the Panzhihua Iron and bloom continuous casting high carbon steel with a protective slag. Gleeble-1500 thermal simulation testing machine to test the heavy rail (U71Mn) high temperature mechanical properties of the steel, and the establishment of the slab lubrication model, using the model to investigate the generation of the main physical properties of the protective slag and slag circle on the slab lubrication impact. High temperature physical properties analyzer, viscometer and DTA1700 thermal analyzer CaO-SiO 2 -Al 2 O 3 -Na 2 O-CaF the relationship of each component 2 -MgO slag system and the content and melting temperature, viscosity and crystallization temperature. Two different test Jardine's column method and melting rate method carbonaceous material fluxes melting speed relationship. And means of X-ray diffraction (XRD), electron microprobe and microscopic observation, the the sample sintering process mineralogical changes in microstructure characteristics were more comprehensive research analysis on this basis the sintering mechanism of the protective slag and carbonaceous material, raw material pretreatment sintering characteristics, slag ring generated reason and analysis from the sintering mechanism established Fluxes sintering characteristics of the quantitative evaluation of class methods and evaluation index system. Under the conditions of this study, the model calculations show that with the fluxes melting temperature, viscosity increases, as well as the formation of slag circle slab lubrication worsening. The high temperature mechanical performance tests show that the the poor heavy rail steel, high temperature plastic, slag focus should solve slab lubrication. Improve protection basicity increase slag the of Na 2 O, CaF 2 , MgO content could reduce the fluxes melting temperature, viscosity, crystallization temperature increased with alkalinity elevated and Na 2 O content increase. Evaluation carbonaceous material types with fluxes melting speed relationship, the melting rate method can be more accurate than slag column reflects the role of the size of different carbonaceous material in the actual production of the melting rate, super carbon black capacity to control the melting rate stronger than the other carbonaceous materials, and the the protective slag sintering be able to be effectively suppressed in the melting process. The sintering characteristics study revealed protection slag sintering process is constituted by a solid phase reaction and liquid-phase sintering. Solid phase reaction at about 600 ℃ to produce mineral phase Ca 2 the SiO 2 the F 2 the of Ca 4 F 2 Si 2 O 7 , etc., as well as certain liquid generated, followed by the emergence of the liquid phase sintering. Test Fluxes sintering process of the body density - temperature relationship and a starting temperature of densification and the densification rate quantitative evaluation of protective slag sintering characteristics. Sintering densification of the initial temperature level and the size of the densification rate is an important factor to affect the protective slag generated slag circle sintering densification of the initial temperature is low or the densification rate of the protective slag in the slag rim production applications easy to generate. In the protective slag, adding carbonaceous material, the raw material is pre-melted or pre-heating treatment can improve the densification of the starting temperature of the protective slag, or to reduce the rate of densification so as to inhibit or reduce the generation of protective slag slag circle. Studies show that the Panzhihua Iron and Steel Bloom Continuous Casting Fluxes chemical composition the wish to CaO and SiO 2 Al 2 O 3 Na 2 O, Chongqing University the Thesis CaFZ and the MgO-based, appropriate to join Bao and SrO special component. Protection slag the alkalinity (Cao/5102), should be controlled at 0.8 0 sup> .9, the melting temperature of 1120 1200 ° C, the viscosity 0.3 0 sup> the SPa .5, crystallization rate of 0%, 1 2% of the super carbon black and 10% flake graphite mixed with carbon mode can be used with carbon mode. Industrial tests showed good protection of the program slag pouring the slab quality, good melting properties in the mold, the suppression of the formation of slag rim, and did not appear to breakout accident.