To improve cleanliness in steel requires a reduction in total oxygen content. The combined EAF-LF-RH-CC process of manufacturing utilized several technologies which reduce total oxygen content. In high carbon chromium bearing steels, total oxygen content has decreased annually and is now 5 ppm on the average.¹⁾ Along with reduced oxygen conent, reduction of the number of oxide inclusions larger than 10 μm has further extended the fatigue life of bearing steel, which was once considered close to the completion. The fatigue life in bearing steels with these smaller inclusions is 5 times longer than that of conventional steels.
A recent study showed that large inclusions can be reduced in size by preventing ladle contamination, air oxidation and flow out ladle slag.