SIBCO Bearing

In aerospace technology, the turbopump bearings that provide liquid fuel for rockets need to operate in liquid oxygen and liquid hydrogen. Its temperature is equal to that of liquefied gas. Due to the presence of martensitic structure in ordinary bearing steel, its toughness is not ideal and it has low-temperature brittleness. If used for low temperatures ranging from -5 to -200 ℃, it will actually corrode due to condensation of water droplets on the bearing surface caused by moisture in the air. Therefore, stainless steel should be used. Generally, martensitic stainless steel is subjected to low-temperature cryogenic treatment to ensure that its structure does not change. The operation test results of SUS4400 steel made radial ball bearings and cylindrical roller bearings in liquid oxygen (boiling point -183 ℃) show that the bearings have no special abnormalities except for some wear on the edge surface, and can withstand speeds up to 20000r/min. However, at this time, the bearing cage must be made of special materials. The retainer of low-temperature bearing itself is also made of stainless steel, commonly used are austenitic SUS304 steel and martensitic SUS440V steel. The former is easy to process and widely used. 

In short, the key technology of low-temperature bearing steel lies in its absence of low-temperature brittleness and corrosion resistance to condensed water. The surface hardness that can be achieved by the martensitic system SUS4400 is HRC56-60, which is lower than commonly used bearing steel. Therefore, its basic rated static load and basic rated dynamic load, or its service life, are lower than those of commonly used bearing steel bearings of the same basic model and size specifications. This must be noted.