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保护渣科学应用是高效化连铸的关键技术,连铸保护渣的重要功能是液渣的润滑和结晶层的传热作用,这些关键作用主要取决于显微结构和矿相组成。然而,Q345B钢连铸保护渣的显微结构及矿相组成国内外相关报道较少,本次研究以实际生产过程中连铸结晶器内坯壳上残留的保护渣渣膜为研究对象,通过岩石学和分析软件相结合的方法开展了研究,取得以下认识:(1)渣膜结构从铸坯表面至结晶器内壁包括结晶层、玻璃层、结晶层和玻璃层4层结构,渣膜厚度分布在0.15~5.00 mm之间,结晶层厚度分布在0.1~1.5 mm之间。(2)渣膜结晶矿相由黄长石、枪晶石和硅灰石组成,同时具有分带性和流动构造,靠近结晶器内壁析出的枪晶石和硅灰石具有晶体成核速率高和成长慢的特点,而分离析晶形成的黄长石晶体发育较粗,黄长石晶体体积的变大可能导致晶内裂缝增多,是导热率下降的主要原因。本次研究有助于改善保护渣成分,提高保护渣的润滑和传热性能,控制铸坯质量,具有一定的理论意义和实际运用价值。
The scientific application of mold powder is the key technology for efficient continuous casting. The important function of mold powder is the lubrication of liquid slag and the heat transfer of the crystalline layer. These key functions depend mainly on the microstructure and the composition of the mineral phase. However, the microstructure and composition of Q345B continuous casting mold slag are few reported at home and abroad. In this study, the residual slag film on the shell of continuous casting mold in the actual production process was studied, (1) the structure of the slag film from the surface of the slab to the inner wall of the mold includes four layers of the crystal layer, the glass layer, the crystal layer and the glass layer, the thickness of the slag film Distributed between 0.15 ~ 5.00 mm, the thickness of the crystalline layer distributed between 0.1 ~ 1.5 mm. (2) The crystalline phase of the slag film is composed of feldspar, gunsolite and wollastonite, and has zonation and flow structure. The spar and wollastonite precipitated near the inner wall of the crystallizer have high nucleation rate and slow growth rate Characteristics, while the separation of the formation of large crystals of yellowstone growth, the larger the volume of the crystalline crystals of the yellow feldspar may lead to increased intracrystalline cracks, the main reason for the decline in thermal conductivity. This study will help to improve the composition of the protective slag, improve the lubricating and heat transfer properties of the flux, and control the quality of the slab, which has a certain theoretical significance and practical value.