Effect of Electroslag Remelting Using 37 Slag on Inclusions in M50 High-temperature Bearing Steel

Abstract

Non-metallic inclusion is a important factor affecting the fatigue property of high-temperature bearing steel. The effect of electroslag remelting （ESR） using 37 slag on inclusions of M50 high-temperature bearing steel was investigated in order to improve the level of inclusion control. Inclusions were characterized by field emission scanning electron microscope equipped with energy dispersive spectrometer. The ingredients of slags before and after ESR was analyzed by X-ray fluorescence method. In the consumable electrode， inclusions were finer Al2O3-SiO2 with high SiO2 content （about 29.3% in average value）. No inclusions clusters were observed.After ESR， inclusions changed to Al2O3， the clusters inclusions with large size were observed. The content of SiO2 in the slag increased from 1.73% to 3.42%， and the Al2O3 content decreased； The content of Al in the steel increased significantly from <0.000 5% to 0.020 7%， and the content of Si in the steel decreased from 0.356% to 0.296%. The metallurgical reaction during ESR was explained based on slag-steel reaction theory. The dissolved Si in the steel reacted with Al2O3 of the molten slag at the interface between molten steel and slag， and the products were dissolved Al and SiO2. Subsequently， dissolved Al diffused into the molten steel and reacted with SiO2 of the inclusions， and the products were dissolved Si and Al2O3. In the end， inclusions in the steel were transformed into Al2O3.The methods to control inclusions of M50 bearing steel during ESR using 37 slag were proposed.

Keywords

• electroslag remelting； high-temperature bearing steel； m50； inclusions； slag-steel reaction； 37 slag