Complex Nonmetallic Inclusions Formed in Billets Heated for Rolling and Characteristics of Structural Steels

Abstract

Complex bimetallic inclusions formed in billets from steels 09G2S and K52 during heating for rolling are studied by methods of electron microscopy and local x-ray spectrum analysis. To check the established evolution of oxide inclusions based on aluminomagnesium spinel and other oxide compositions, individual inclusions of manganese sulfide and complex oxide-sulfide inclusions, a method developed by the Severstal’Company and the Karpov NIFKhI for determining the content of corrosion-active nonmetallic inclusions (CANI) as a function of the heating mode is applied to the steels studied. It is recommended to increase the temperature and duration of heating of billets for hot rolling in order to lower the content of CANI and to raise the resistance of the steels to local corrosion.