Method for improving compactness of continuous casting bearing steel core

Abstract

The invention relates to the technical field of bearing steel, in particular to a method for improving the compactness of a continuous casting bearing steel core. The method specifically comprises the following steps that (1) the temperature of a tundish is 1465-1480 DEG C, the pulling speed is kept constant, the specific water flow of secondary cooling water is 0.20 + / -0.02 L / kg, the electromagnetic stirring current of a crystallizer is 530 + / -50 A, the electromagnetic stirring current of the tail end is 580 + / -50 A, and the frequency is 6 + / -0.5 Hz; the heat preservation time is not less than 30h; (2) the temperature of a preheating section is lower than 600 DEG C, the temperature of a second heating section is 880-920 DEG C, the temperature of a first heating section is 1230-1260 DEG C, the temperature of a soaking section is 1200-1220 DEG C, the heat preservation time of the soaking section is longer than or equal to 2 h, and the total heating time is longer than or equal to 9 h; (3) the blooming temperature ranges from 1100 DEG C to 1200 DEG C, isothermal operation is carried out in front of a fourth continuous rolling mill, and the isothermal time ranges from 2 min to 3 min; and after the surface temperature is reduced to 950-970 DEG C, rolling in a continuous rolling mill, and the final rolling temperature is less than or equal to 950 DEG C. The technology is simple and easy to implement, the requirement for equipment is not high, the bearing steel core part has no shrinkage cavity under acid leaching macroscopic inspection, and the ultrasonic flaw detection result is above grade B.

Description

technical field [0001] The invention relates to the technical field of bearing steel, in particular to a method for improving the compactness of a continuous casting bearing steel core. Background technique [0002] Since the beginning of the 21st century, with the technological progress and rapid development of my country's transportation, petrochemical, heavy machinery, marine engineering, nuclear power and military industries, higher technical requirements have been put forward for the quality, performance, specifications and dimensions of steel products. , thereby vigorously promoting the development of production technology and equipment control technology for wide (special) slabs, large-section square (round) billets and other wide-section continuous casting billets. At present, the sections of advanced continuous casting machines at home and abroad tend to be wider, such as Japan's Sumitomo Wakayama, Xingcheng Special Steel, Dalian Special Steel, Jiyuan Steel, etc., wh...

AI Technical Summary

Problems solved by technology

However, during the research process, the researchers found that due to the increased deformation resistance and deformation caused by the thickening of the slab, the non-uniform diffusion and distribution of the solute caused by the widening of the slab increased, and the internal cracks caused by deformation under heavy pressure With the change of many conditions such as risk multiplication, the behaviors of billet shell deformation in the two-phase zone, solidification heat transfer, solute micro-segregation, and solute macro-diffusion during the implementation of the heavy reduction (rate) at the solidification end of the wide-section continuous casting slab become more complex and changeable , the interaction between behaviors becomes more prominent and cannot be ignored

Practice has proved that the existing research methods and conventional reduction process theory are difficult to guide the design of continuous casting machine reduction parameters, and can only rely on repeated industrial tests for continuous optimization and debugging, which seriously restricts the implementation effect and stability of the reduction process

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