Micro-segregation controlling method of bloom heavy rail steel

Abstract

The invention discloses a micro-segregation controlling method of bloom heavy rail steel, and belongs to the field of iron steel metallurgy. The controlling method is carried out at a continuous casting stage according to the following steps: 1, performing continuous casting electromagnetic stirring under a condition that the stirring magnetic field strength for electromagnetic stirring is 40x10<-4> to 50x10<-4>T in a combined way of electromagnetic stirring and secondary cooling electromagnetic stirring, and ensuring that a concrete mounting position for the secondary cooling electromagneticstirring has a distance of being 5.0 m to 6.0 m away from molten steel surface of a crystallizer, the stirring current frequency is 6.0 Hz to 8.0 Hz, and the magnetic field strength is 180x10<-4> to 200x10<-4>T; casting the molten steel by using a medium ladle at an overheating degree being 35 DEG C to 45 DEG C; and requiring a secondary cooling area to be in the coverage of 15.0 m away from the molten steel surface of the crystallizer at a continuous casting secondary cooling stage. The controlling method is carried out based on the parameters, so that the local condensation velocity of the bloom heavy rail steel is improved, and composition of condensation tissues of casting blanks are improved and controlled; columnar crystals are relatively developed, crystal bars are thin and compact,a crystal grain form of an equiax crystal is changed, and the crystal bars are thin, compact and clear; and a space of a secondary dendrite arm is reduced, and the micro-segregation extent is controlled preferably.

Description

technical field [0001] The invention relates to the field of iron and steel metallurgy, in particular to a method for controlling microscopic segregation of heavy rail steel with large billets. Background technique [0002] Steel rails are the main components of railway tracks. During railway transportation, to provide effective support and guidance for locomotives, they need to bear huge vertical pressure from wheels. Based on the development needs of my country's infrastructure construction, railway transportation is developing at a rapid speed, and it is becoming more and more high-speed and heavy-duty. This undoubtedly puts forward more stringent requirements on the quality of rails. In addition, my country's steel rails continue to go abroad and become an important part of the international business card. The quality of my country's steel rails affects the application and also affects my country's international image to a certain extent. [0003] The improvement of ra...

AI Technical Summary

Problems solved by technology

However, in the process of practical application, it is found that microscopic segregation affects the control of microstructure, and also affects the control of inclusions precipitated by segregation and precipitation under low temperature conditions. Therefore, the control of microscopic segregation has an important impact on the homogeneity and cleanliness control of heavy rail steel.