Method for controlling center porosity defect of bearing steel

Abstract

The invention provides a method for controlling a center porosity defect of bearing steel. Continuous casting adopts a weak cold system and low superheat and low drawing speed, a tundish adopts soft fire and automatic baking, electromagnetic stirring current intensity and frequency of a crystallizer are controlled, the heating charging temperature is smaller than 850 DEG C, the temperature of a soaking zone ranges from 1200 DEG C to 1220 DEG C, the heating total time is larger than or equal to 5 hours, high reduction rolling is adopted, the first two rolling reduction is controlled between 70mm and 80mm, and finished products are piled in a mode that multiple tanks are continuously piled in each steel tanks. By means of the method, continuous casting of the bearing steel can be achieved, slag blocking and control of oxygen content of tapping in the smelting process of a converter are not needed, special top slag modification treatment is avoided when refining is performed, the problem of water port blockage caused by impurities of the bearing steel can be effectively avoided, quality level of macrostructures of the bearing steel is greatly improved, inherent quality and using performance of bearing steel are improved, and the quality qualified rate of the bearing steel is increased.

Description

Technical field [0001] The invention belongs to the field of iron and steel metallurgy technology, and in particular relates to a control method for preventing bearing steel from producing center loose defects. Background technique [0002] The use of bearing steel is mostly under the conditions of coexistence of various alternating loads such as tensile stress, shearing force and friction. Therefore, the bearing steel after rolling must have a high and uniform hardness, that is, the bearing steel used should have strict The uniformity of the microstructure, especially the degree of segregation of carbon, sulfur, and phosphorus in the macro and microstructures, and the uniformity of the size, spacing and morphological distribution of precipitated carbide particles, so that the quality of the low-magnification structure of bearing steel puts forward higher requirements. [0003] Due to the long distance from the liquidus line to the solid phase of high carbon chromium bearing steel,...

AI Technical Summary

Problems solved by technology

[0003] Due to the long distance from the liquidus line to the solid phase of high-carbon chromium bearing steel, low-magnification structural defects are more likely to occur

Especially when the continuous casting production process is used to produce bearing steel, because the continuous casting production process has greater cooling intensity than die casting, and the interface temperature gradient is large, it is easy to cause the enrichment of dendrites, resulting in periodic and intermittent cracks in the center of the slab. Shrinkage cavity and central segregation, accompanied by central porosity and fine pores, directly affect the internal quality and performance of bearing steel, reduce the quality pass rate of bearing steel, and cause unqualified accidents

In order to prevent the looseness of the center of the bearing steel, the current measures are to control the number of continuous casting, improve the slag blocking effect, control the oxygen content of the steel, and carry out a series of technological means such as refining and top slag modification, which not only increases the production process, but also increases the control difficulty