Study of Evaluating Method for Non-Metallic Inclusions and Development of Slag Refining for Bearing Steel

摘要

The evaluation of the nonmetallic inclusions is very important to estimate the rolling contact fatigue life of bearing steel. The study of the ultrasonic testing as nondestructive testing made it clear that the nonmetallic inclusion over 10 μm could be detected and there was a relationship between the flaking and the nonmetallic inclusions in the rolling contact fatigue life testing. On the extraction of the acid solution and Coulter counter method, the changes of the nonmetallic inclusions in molten steel was analyzed and the higher basicity · less SiO_2 slag refining reduced the quantity of the nonmetallic inclusions over 20 μm size to 75% compared with the conventional refining method.