Summary of Rolling Bearing Steel

The steel applicable for various rolling bearing ferrules and rolling elements working in different conditions are collectively called rolling or ball bearing steel. Because bearings can be adapt to different working conditions, such as low temperature, high temperature, rust resistance, anti-magnet and vibration resistance etc. Bearing steel can be special carbon chromium bearing steel, and it can also be tool steel, structural steel, stainless steel and heat-resistant steel. Carbon chromium bearing steel is the most widely used bearing steel at present. Because bearing steel includes many types of steel, it is provided with many uses. Generally speaking, when used as inner bearing material, it should be in high quality, and it should be provided with high uniformity of sonim and carbide in particular. Therefore, bearing steel is produced by special techniques, such as vacuum degassing, electrostag remelting and vacuum self-consuming remelting etc. Carbon chromium bearing steel is usually provided with higher metallurgical quality, so it is also perfect material for cold-working mould and fine measuring instrument.

According to bearing steel production and usage practice in our country, referring to the existing circumstances of homogeneous steel at home and abroad, the bearing steel is divided into five types, namely high-carbon chromium bearing steel, bearing steel without chromium, carburized bearing steel, stainless bearing steel and high temperature bearing steel. There are fifteen steel grades; wherein, seven of them are standard steel grade, and eight of them are nonstandard. The bearing steel is scarce in steel type and complete in steel grade, so it can fundamentally satisfy requirements of bearing industry product, and the plant supervision is convenient. 

There are only four types of bearing steel in most countries, but bearing steel without chromium is added in our country. 4¡«5 high-carbon chromium bearing steel is generally retained at abroad. Steel grades such as GCr6 and GCr9 are provided with low hardenability and there may be soft spots in quenching, so they have been eliminated since then. Molybdenum is added to high-carbon chromium bearing steel to enhance hardenability, such as 3 and 4 of 52100 series in America, SUJ4 and SUJ5 in Japan, SKF23 and SKF 25 in Sweden etc. There are no such steel grades in our country. GCr9 is retained in bearing steel of our country. Bearing steel without chromium is also researched at abroad. For instance, the steel was researched in America in 1941 and was reported in Japan in 1965, but it was not listed in standard. Maybe it is the reason that it is provided with inferior corrosion resisting property compared with chromium bearing steel. Carburized bearing steel existing at abroad is provided with complete steel grades, and it is widely used. For instance, the carburized bearing steel used in America is one third of the total, and it is 15% in Japan. There are more than ten carburized steel grades for small-sized, medium and small-sized, large-sized and oversized bearings. But there are only two carburized steel grades for oversized bearings in our country. And carburized steel grades for medium and small-sized are being developed and perfected at present. The development situation of stainless bearing steel and high temperature bearing steel is similar to situation at abroad. 

Some data of high-carbon chromium steel and 9Cr18Mo steel and machinability of other steel grades are obtained from other documents. Because the test methods for measuring wearing capacity and contact fatigue property are different, test conditions are marked behind each data.