| The present work focused on solving the current dilemma situations during production process for high carbon hard wire steel of 82B,such as high rate of drawing breakage,poor rod cleaning,unsteady sorbite structure,and uneven grain size,which caused by the high gas content,oxide inclusions and shrinkage porosity in casting billet.The specific approaches are proposed to improve the deoxidization process,optimization of 150t production line of smelting process parameters,the molten steel purity,casting quality control,controlled rolling,cold hands and comprehensive consideration of steelmaking,rolling,cooling,aging,drawing processing factors,such as aluminum de-oxidation,slag basicity industrial test of the impact of total oxygen and inclusion.In addition,we used the analysis methods of mechanical properties test and metallographic microscope to solve the problem of brittle fracture of 82B drawing and optimize its performance.Through industrial test showed that de-oxidation without aluminum?SiCaBa?technology makes the steel aluminum content is controlled in the range of 0.004%-0.006%,with aluminum de-oxidation?Aluminum and iron?steel high aluminum content to 0.012%-0.034%.The steel using de-oxidation without aluminum in Al2O3 content of 31.12×10-6 on average,compared with the al killed was reduced by 43.8%,effectively reduce the brittle inclusion in steel;The analysis of the mechanical testing indicated that the process using de-oxidation without aluminum can slightly improve the 82B wire rod elongation and reduction of area,reduce the incidence of brittle fracture of the drawing;refining slag material with high basicity is about 4.0 for steel deoxidized,oxygen content to meet minimum for 9-10×10-6.The results from the metallographic microscope showed that the slag inclusion procedure is the main cause of slab cleanliness variation,and LF refining can effectively reduce the non-metallic inclusions in steel.After refining T[O]in steel by 63.25×10-6 was reduced to 24×10-6,the drop is about 62.06%;[N]in molten steel before LF soft blowing increased from 10.25×10-6 to 24.25×10-6,increased 136.59%,increase[N]more during refining process.Liquid steel superheat at 10-30 ? segregation percent of pass and loose level of qualified rate is higher,while the shrinkage is small and stable;slab quality is good and stable when continuous casting speed within the range 1.6 m·min-1-1.8 m·min-1,but the slab quality decreased obviously when drawing speed increased to more than 1.8 m·min-1.By casting metallographic examination A,B,C,D class inclusions single rating is less than 1.0 on the Richter scale,inclusion rating is less than 2.5,the sum of coarse inclusion control within 0.5,does not appear large inclusions;82B wire rod on average nitrogen content is reduced from 68×10-6 to 42×10-6,obviously improved the quality of continuous casting billet,slab shrinkage cavity with grade 2 or less proportion of 98%or more,center carbon segregation index averaged 1.08.The problems on quality control for rod production of high carbon hard wire 82B are effectively solved. |
PDF Full Text Request