Is known as the pearl on the crown of aerospace launch machine bearing is what material made of?

Traditional airlines launched main bearing data is M50. In the 1980 s, M50 based on M50NiL, it adds a nickel, reduces the carbon, carburizing steel is a kind of appearance. Two is the main ingredient in the diagram below. M50NiL appearance hardness can be up to 60 ~ 64 HRC. Figure, M50 and M50NiL composition profiles airlines launched machine in order to ensure the bearing working under high DN value, high temperature and load, its inner and outer ring and roller hardness is not less than RC58, otherwise the damage of bearing will present 'crushed'. Up the working temperature, the hardness of materials will also be gradually landing. Usually use the most common is the SAE 52100 bearing steel, when work environment beyond 175 degrees Celsius, hardness is lower than RC58, once can't comply with the demand of modern navigation of main bearing, as shown in the figure below, WB - high temperature bearing steel 49 the maximum temperature can reach 537 degrees Celsius. Airlines launched machine speed and turbine gas temperature before the increasingly rising, the working temperature of main bearing and also from time to time. Bearing working temperature range is quite widespread, it can request in - namely 55 degrees Celsius is easy to start to work at high temperature, also need to keep up with the temperature change after parking. When a machine parking, bearing lubricating oil cooling circulatory system to suspend the work, turbine blades, wheel and axle of the residual heat conduct also gradually to the turbine bearing, with the increase of parking time and the temperature of the improve step by step. Ordinary parking in 40 minutes later, the temperature of the turbine bearing can also higher than that of normal working temperature of 100 ~ 150 degrees Celsius. When the bearing working temperature is below 175 degrees Celsius, can use ordinary SAE52100 bearing steel. MHT bearing steel is added in the SAE52100 1. 3% of aluminum, its working temperature can ascend to 260 degrees Celsius. M - 50 applicable temperature at 170 ~ 315 degrees Celsius. M1 and M2 hardness can meet the request in 500 degrees Celsius, but it is also in order to limit their antioxidant properties. WB- 49 carburizing steel is high temperature performance is good, able to work at 537 degrees Celsius, but the current manufacturing process lacks to make solid ball, and can only be used for inner and outer ring. M1 material will be used on ball.