A Control Method for Eliminating Mottling Defects in Medium and Heavy Plates

Abstract

The invention relates to a control method for eliminating a spot defect of a moderately thick plate and belongs to the technical field of metallurgy. The method comprises the following steps of (1) a heating stage: carrying out high pressure water phosphorus removal after heating a continuous cast slab through controlling a heating coefficient; (2) a rolling stage: carrying out multi-pass high pressure water phosphorus removal in a hot rolling process; and (3) a cooling stage: cooling a hot rolled plate in an ultrafast cooling and laminar cooling combined way to prepare the moderately thick plate. Through the control on the temperature and the atmosphere in the heating stage, the matching of the rolling temperature and a phosphorus removal process in the rolling process and the combination of the ultrafast cooling and laminar cooling ways in the cooling stage in the control method disclosed by the invention, the straightness of an iron oxide scale and an interface is obviously increased; and no residual iron oxide scales are remained on the surface of a steel plate through subsequent sand blasting and shot blasting, so that the generation of the spot defect is effectively inhibited, and the surface quality of the moderately thick plate is obviously improved.

Description

Technical field: [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a control method for eliminating mottled defects of medium and thick plates. Background technique: [0002] Medium and heavy plate is an important steel material necessary for the development of the national economy, an indispensable steel product for the country's industrialization, and an important symbol of the level of the country's steel industry and steel materials. From the perspective of industrialized countries in the world, the demand for medium and heavy plates accounts for about 10-16% of the total steel products. In recent years, the production of medium and heavy plates in my country has been increasing year by year. With the rapid development of medium and heavy plate equipment and technology in recent years, great progress has been made. With the increase of medium and heavy plate varieties, the expansion of application fields and scope , users pay...

AI Technical Summary

Problems solved by technology

After the steel plate comes out of the heating furnace, a eutectoid structure of silicon spinel and FeO will be formed at about 1173 ° C. This structure is not easy to remove during the descaling process. After descaling, the remaining silicon spinel and iron oxide scale decrease with the temperature. As the hardness increases, the mixture of silicon spinel and iron oxide scale remaining during the rolling process will be pressed into the steel matrix, making the interface between the oxide scale and the steel matrix worse, which in turn will increase the difficulty of sandblasting and shot blasting

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