Abstract
Abstract By laboratory slag/steel reaction equilibrim experiments, the viriation of oxygen content, inclusion compositions and inclusion sizes were studied. The effect of acid slag treatment on the transition mechanisms of D-type inclusions and the precipitation of TiN inclusions in GCr15 bearing steel were explored. The obtained results showed that the dominant inclusions in steel were plastic and smaller Al2O3-SiO2-MnO. The melting point were lower than 1400°C treated by the acid refining slag of 35.1%CaO-15%Al2O3-43.9%SiO2-6%MgO and there was no TiN found. The evolution of MgO·Al2O3 inclusions is: MgO·Al2O3 → MgO·Al2O3·SiO2·MnO→ Al2O3·SiO2·MnO. Mg and Al from MgO·Al2O3 inclusions were displaced by [Si] and [Mn] in steel liquid , and formation of plastic Al2O3-SiO2-MnO inclusions finally, whose compositions distribution were uniform. Mg and Si, Mn were complementary in inclusions as to the spatial distribution.
Highlights
As one of the most commonly used high-chromium bearing steels, GCr15 has been widely used in manufacturing bearing ring, ball screw and other mechanical components [1]
The stress concentration can be caused between the steel matrix and the interfacial, which caused fatigue cracks and fatigue life reduction of the bearing steel [8]
Jiang [9] found that the inclusions with low melting point had good deformation ability, and they were found in liquid form with special shape which were easier to remove
Summary
As one of the most commonly used high-chromium bearing steels, GCr15 has been widely used in manufacturing bearing ring, ball screw and other mechanical components [1]. There is low oxygen content in GCr15 after high basicity refining slag treatment, which achived high cleanliness, most were D-type inclusions including MgO·Al2O3, MgO and calcium-aluminate [7]. The inclusions such as MgO·Al2O3, calcium-aluminate and christobalite had no plastic deformation ability under the conventional hot working temperature of steel. The treatment effect of acid slag basicity and compositions on D-type inclusion were analyzed. The detailed experimental process is described as follows: (1) 70g billet blocks and 10.5g acid slag were placed into the Al2O3 crucible to melt in the tubular resistance furnace. The detailed experimental process is described as follows: (1) 70g billet blocks and 10.5g acid slag were placed into the Al2O3 crucible to melt in the tubular resistance furnace. (2) The furnace was heated up to 1600∘C gradually under argon protective atmosphere with a volume flow of 4 L·min−1. (3) After melting clear, the temperature was maintained at 1600∘C for one and half an hour to homog-
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