Metallurgy Technology of Bearing Steel
Bearing steel is a kind of steel with high wear resistance, high surface quality and small shape and size error size, which is closely related to human life. Bearing steel is widely used in various industries such as automobile, machinery, hardware and electronics because of its superior performance. Bearing steel is produced by smelting method, and its metallurgical technology is the key to ensure the quality of bearing steel.
Steel is a major material for bearing production. Through the smelting process, impurities in the steel are removed, and adding trace elements to the steel can improve its important performance such as wear resistance, fatigue strength and hardenability. In order to guarantee the quality of bearing steel and improve its economic efficiency, the most cost-effective and efficient steel smelting process and optimization of the trace element content are the technical frontier of bearing steel production and related areas.
The general process of bearing steel smelting is: to smelt semi-finished products (casting, forging, rolling and extrusion) into liquid steel, and then remove impurities such as C, S, P, O, N and H through Continuous Casting, Refining and Casting process. In the process of steelmaking, in order to control the chemical composition of molten steel and mechanical properties of steel, deoxidizer, desulfurizer and nitrogen-removing agents are added. The trace element is added to the molten steel according to the given requirements before or after refining, and the concentration of trace element in molten steel is kept in the range of 0.003%~0.02%.
Bearing steel requires not only good mechanical properties, but also good surface quality. In order to obtain good surface quality, the smelting process must be optimized. Increasing the speed of liquid steel flow through the nozzle can reduce its contact time with oxygen, so as to reduce the possibility of the surface oxidation of the steel, and improve its surface quality. In the process of smelting bearing steel, low sulfur and phosphorus content is also an important part. If their content is too large, the adhesion force between the crystals and the liquid steel will be increased, making it difficult to form uniform and compact grains and reducing the surface quality of the steel.
In order to meet the performance requirements of bearing steel, it is necessary to adjust and control the smelting process. The adjustment of smelting by controlling the temperature, stirring and flow rate will be necessary to ensure the quality of bearing steel. Generally, the temperature of bearing steel should be controlled below 1500°C, and the temperature should be maintained for a long time. The purpose of controlling the stirring time and stirring intensity is to improve the quality of steel liquid. Stirring during the refining process can also break up macromolecule oxides, making them easier to separate from the steel. In addition, adding lubricants in the ladle can improve the surface quality of steel.
In summary, the metallurgical technology of bearing steel has a great influence on the quality and performance of bearing steel. The smelting process of bearing steel needs to be tested and optimized in a short time, which is the focal point of current bearing steel production. It is necessary to adjust the process parameters, optimize the refining and casting process and control the trace elements in molten steel, so as to ensure the good performance of bearing steel.
