Improving Production, Control and Properties of Bearing Steels Intended for Demanding Applications

The advances of ladle metallurgy have led to very significant developments in the internal cleanliness of low alloy steel products. This development, which started with the design of the first functioning ladle furnaces with effective stirring facilities, has now reached a level where “standard” produced steels outperform complex and costly remelting processes. The steel making advances necessitates corresponding developments in testing procedures, perhaps in particular as concerns the control of the non-metallic inclusion contents of steel. The developments in steel processing are reviewed and recent progress in the rating of non-metallic inclusions is detailed, in particular as regards test methods encompassing ultrasonic techniques. Further, recent advances in assessing fatigue initiation causes in bearing steels are discussed and related to contents and morphology of micro-inclusions.