Controlled cooling and controlled rolling method for control over bearing steel wire network carbide

Abstract

The invention relates to a controlled cooling and controlled rolling method for control over bearing steel wire network carbide. The controlled cooling and controlled rolling method is characterized by comprising the steps that a bar is quickly rolled into a wire with the specified specification to be subjected to spinning, scattered rolls are made, the final rolling temperature is controlled to be 780- 880 DEG C; the spitting temperature is controlled to be 750-850 DEG C; the continuous scattered rolls are subjected to on-line controlled cooling through EDC water bath isothermal quenching cooling, the cooling speed is controlled to be 2.0- 10 DEG C / s, and the final cooling temperature is controlled to be 620-630 DEG C; cover-adding slow cooling is conducted after EDC water bath isothermalquenching cooling, and the temperature when the scattered rolls are taken out from a cover is controlled to be 400-500 DEG C; and the rolls are collected after slow cooling, and air cooling is conducted to the room temperature. The disc rolls are subjected to controlled cooling through a mode of EDC water bath isothermal quenching cooling and cover-adding slow cooling, precipitation of the carbide in the cooling process can be effectively inhibited, a non-equilibrium microstructure is obtained, the small-strip-shaped or hemispheric carbide is formed, and finally, the network carbide is controlled.

Description

technical field [0001] The invention belongs to the technical field of iron and steel manufacturing, and in particular relates to a controlled cooling and rolling method for controlling the carbide network of bearing steel wire rods. Background technique [0002] The carbide network is formed by precipitation at the austenite grain boundary during the slow cooling process after high final rolling temperature. Once the carbide network is formed, especially the carbide completely surrounds the grain boundary, and is wide and When it is thick, microcracks will be generated along the grain boundaries during subsequent processing and use, which will greatly reduce the service life of the rolling elements. [0003] First of all, the serious carbide network cannot be completely eliminated in the subsequent spheroidizing annealing, so that it is easy to produce wear cracks, also called cracks, during the grinding process of bearing processing; secondly, if the original carbide netwo...

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Problems solved by technology

Its invention increases the cost of steelmaking and the difficulty of steelmaking through compositional adjustment, but without the guarantee of subsequent cooling control process, it is impossible to realize the control of carbide network precipitation

[0006] The method disclosed in the application number 200910062664.X for reducing the carbide network level of bearing steel wire rod mainly involves cooling the wire rod through air cooling after spinning, and the air cooling speed is controlled at 2°C / s-10°C / s. The method can control the cooling of the wire rod, but there will be a high temperature difference between the middle of the wire rod and the overlapping point after air cooling, resulting in the inhomogeneity of the overall carbide network quality of the wire rod

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