Effect of Various Aluminum Content on the Formation of Inclusion

Abstract

More attention is paid to high aluminum steel which attains hardness, abrasive resistance and corrosion resistance. However, the development of subsurface nitrides and oxides in a nitrogen-rich atmosphere during smelting process and solidification makes a significant effect on the properties of high aluminum steel. It is important to understand how theses nitrides and oxides form and their consequences for the quality of steel products. In the current study, the effect of various aluminum content on the formation of inclusions in a nitrogen-rich atmosphere was investigated using vacuum induction furnace and high-temperature contact angle device. The growth and evolution of the precipitation in a subsurface oxygen-depleted region were evaluated by means of optical microscope and scanning electron microscope. The depth of the internal oxide and nitride zones were different in the samples containing various aluminum content. Increasing aluminum content to a given value has an influence on modifying the surface oxide scale composition and increasing its continuity, which gradually decreased the internal precipitation zones with increasing aluminum content. For the sample with higher aluminum content, a thick continuous oxide layer formed and completely prevented nitrogen penetration into the bulk of the samples.