工艺条件对铬系白口铸铁组织及耐腐蚀性的影响-材料加工工程专业论文.docxVIP

西安建筑科技大学 西安建筑科技大学硕士论文 Influence of Process Conditions on Microstructure and the Corrosion Resistance for Chromium White Cast Iron Specialty： Meterials Processing Engineering Name: Li Sheng Instructor: Prof. Ma Youping ABSTRACT High chromium cast irons are applied to metallurgy, mine and building materials processing due to the high hardness, high wear resistance and corrosion-resistance of acids and bases. In practical application, it is well known that high chromium cast irons were easily subjected to intergranular corrosion in corrosion medium, especially in strong acid medium. With the aggravation of corrosion, the support roles of matrix to eutectic carbides were weakened. In the slurry washout conditions, carbides would completely fall off or fracture from matrix, which has serious consequences for functions of good wear resistance. White cast irons with different Cr contents were chosen as research object. The microstructure morphology and distribution of wear resistant phase were obtained by the change of technological conditions. The influence law about technological conditions on carbides amount, morphology and distribution was discussed. The characteristics during corrosion were explained by the law. The study results showed that the solidification microstructure of eutectic white cast irons containing 10% Cr，12% Cr，15% Cr，18% Cr，23% Cr，28% Cr had significant changes with the change of cooling condition, especially the morphologies and distributions of carbides. The corrosion tests results were influenced accordingly. In the samples of experimental conditions, the carbide size of solidification microstructure by sand mold casting (slow cooling rate) generally was bigger than that of metal mold casting (relatively quick cooling rate), in addition, the carbides were lath shaped by sand mold casting. The net M3C carbides with big spacing were observed in white cast irons containing 10% Cr, which directly influenced wear resistance and anti-corrosion. With the