Research On Quality Control Of Continuous Casting Round Billet For Oil Casing Steel 37Mn5 Of Long Steel

In recent years,with the socialization of the fast lane and the rapid development of the oil industry,the demand for well tube steel and tube billet steel is increasing,which is accompanied by more stringent requirements for the quality of steel.According to market demand,Shaan steel group Long Steel company(Long Steel)develops and produces J55 grade 37Mn5 oil casing steel.However,there are quality problems such as loose core,shrinkage hole,crack and fixed length in the continuous casting round billet of 37Mn5 produced by the long process of mixing iron furnace,iron water bag,120 ton converter,blowing argon station,LF furnace and continuous casting.In order to reduce the quality defects appearing during trial production of Long Steel continuous casting round billet,the high quality requirement of continuous casting round billet is achieved.The following aspects are analyzed in the following aspects.The first,the quantitative and qualitative analysis of inclusions is carried out through experimental research.Second,the method of combining practical production data with theoretical calculation is used to optimize the converter and refining process.Third,numerical simulation is carried out by Fluent software to optimize the process parameters of continuous casting.Through the above three aspects of analysis and research,we get the following conclusions:(1)The inclusions were quantitatively and qualitatively analyzed by metallographic microscope and scanning electron microscope,and the inclusions were classified,and the reasons for the defects of circular billet in Long Steel 37Mn5 were explored.(2)The method of combining numerical simulation and production practice data with theoretical calculation is adopted to provide theoretical support and technical guidance for the production of 37Mn5 continuous casting round billet of Long Steel by optimizing three aspects of deoxidization alloying system,deoxidization system of LF refining process and parameters of continuous casting process.(3)Through the optimization of converter,LF and refining process,the 37Mn5 continuous casting round billet with good quality is successfully produced by using the mixing furnace,iron water bag,120 ton converter,LF refining furnace and round billet continuous casting.The chemical composition of 37Mn5 continuous casting round billet produced after the improved process is in conformity with the national standard,the surface quality is well tested and the internal quality is controlled.The quality problems of J55 grade 37Mn5 produced by Long Steel were solved,and the quality of products was improved.