Production of High-carbon Chromium Bearing Steel in Vertical Type Continuous Caster

The rolling contact fatigue life of bearing steel is improved with decreases in the oxide nonmetallic inclusions. The oxygen content of high carbon chromium bearing steel has been reduced to an average level of 5.8ppm. This is accomplished through the combined processes of an electric arc furnace, a ladle furnace, an R-H vacuum degassing vessel and a continuous caster.The rolling contact fatigue life of high-carbon chromium bearing steel thus manufactured has accordingly doubled to tripled on the test of a thrust type machine if compared with the results of the conventional vacuum degassed, ingot cast steel.The supply of extremely low oxygen steel to the caster has resulted in the elimination of such troubles as nozzle clogging. From the operational standpoint, it has been the main contributor to a record 10 000t of continuous cast high-carbon chromium bearing steel from one tundish-one nozzle without interruptions.It has been demonstrated in the life tests that neither sulfur nor titanium has an influence on the life when the levels of these elements are held down to a minimum in the high-carbon chromium bearing steel. The life is further extended by the cold working inherent to cold pilgered tubes. The improvement has been found out in the tests to double to triple life of hot worked hollow tubes.