The raw steel used to produce high precision miniature bearings is processed with additional melting steps. The result is a type of steel with very uniform fine grain material structure, the bearing contact surfaces can be super finished very smooth so the bearing is very quiet.

The most common heat treating method for chrome steel is to thru harden the steel in a controlled atmosphere furnace. Bearings manufactured from chrome steel can operate at continuous temperatures up to 120°C.

Where higher temperatures are encountered, it is possible to Heat Stabilize the bearing components. By varying the heat treating process, bearings can be produced so they are capable of operating at temperatures of 220°C, and higher. For these applications, the components must be subjected to a tempering treatment at a higher temperature corresponding to the service temperature. This elevated tempering treatment has a detrimental effect on the hardness of the material and the load carrying capacity of the bearing is reduced.

SAE 52100 is an excellent general purpose bearing steel. Due to its excellent hardness and wear resistance, it exhibits good fatigue life in rolling element bearings. However, the corrosion resistance of chrome steel is poor because of the low chromium content. The surfaces of the bearings must be protected with a coating of rust inhibitor or oil to stop oxidation.

Did you know that the standard chemical composition of chromium steel will vary depending on the country where it is produced? Details like this can make a big difference in bearing performance, and the AST team is ready to make sure you’re using the right part for your application – contact them for engineering and design assistance.