(1) the import of high temperature bearing steel work requirements
Modern technologies such as nuclear power systems, jet engines and gas turbines operating temperature constant even up to several thousands of degrees Baidu ,, apparently ordinary steel bearings can not be applied. You must use steel or other high temperature bearings high temperature materials.
Generally considered than 120 ℃ temperature conditions, high temperature operating conditions, it is considered, then the ordinary steel bearings organizational change will occur and yield strength decreased gradually lose precision; and when the operating temperature exceeds Bearing Bearing material tempering temperature, which decreased the hardness, the hardness decreased sharply when the working temperature exceeds 180 ℃, and soon early fatigue and wear.
Bearing ensure accuracy at high temperature operation and service life of the central link is to ensure that imported bearings have sufficient hardness and stability of size and shape at high temperatures, so the high-temperature steel bearings made the following requirements:
1) high temperature hardness of not less than HRC50 ~ 56; microstructure stability;
2) good high-temperature dimensional stability, thermal expansion coefficient is small, no significant changes in the organization, good creep resistance, low residual stress;
3) good oxidation resistance, the resulting oxide film and the substrate with a solid, and good wear resistance and fatigue strength, thermal shock resistance, can withstand rapid temperature changes, better thermal conductivity;
4) Other material properties as steel bearings should have.
Common steel (2) high-temperature bearings low load situations below 180 ℃, and can be used for high temperature tempering steel bearings (160 ~ 300 ℃) to use, if the hardness does not comply, could be replaced by sub-high temperature bearings steel GCrSiWV , the operating temperature of the steel at about 250 ℃. May be employed at a temperature of about 300 ℃ of Cr4Mo4V, below 538 ℃ can W6Cr4Mo5V2, over this temperature using a cobalt-based, chromium-based or a molybdenum-based alloy bearings, and titanium carbide can be used when the temperature exceeds 81 ℃, the tungsten carbide ceramic materials such as metals, can be used at higher temperatures, such as zirconia ceramic materials, the use of such material imported bearings can withstand the maximum working temperature up to 1650 ℃.