Effect Of Deformation And Oxygen Content On FeO Eutectoid Reaction Of Oxide Scale On High Strength Steel Surface

During the hot rolling process of the steel,a large amount of oxide scale will be produced on the surface and its powder falls off in the subsequent processing and forming,which will pollute the environment and also affect the surface quality of the steel.Therefore,this paper studies on the formation of surface scale and Fe O eutectoid reaction during hot deformation of high-strength steel,explores the impact of oxygen atmosphere on Fe O isothermal transformation in oxide scale,and analyzes the influence of surface condition of steel after shot peening on the formation of oxide scale after heat treatment.Through these studies,the innovative research results obtained are as follows:The thermal deformation promotes the precipitation of pro-eutectoid Fe₃O₄ and the eutectoid transformation of Fe O.However,with the increase of the deformation amount,the pores in the oxide layer increase,which can inhibit the growth ofα-Fe new phase in the Fe O layer and hinder the eutectoid transformation.The steel with high Si content has a dense spinel structure near the matrix,which hinders the diffusion of iron ions,and the eutectoid reaction of Fe O occurs.By contrast,the eutectoid is suppressed in steels with low Si content.When the oxygen content is lower than the oxygen content in the air,there is no small block pro-eutectoid Fe₃O₄ in the generated oxide scale,and no eutectoid structure appears.When the oxygen content is close to or higher than the oxygen content in the air,with the increase of oxygen content,there are more and more small block pro-eutectoid Fe₃O₄ and lamellar eutectoid structures on Fe O.The Fe₃O₄ layer in the oxide scale formed in the high oxygen environment is thicker.The surface condition of the steel after shot peening affects the formation of scale after quenching and tempering heat treatment.For samples with a complete oxide layer and residual oxide scale on the surface,the content of small pro-eutectoid Fe₃O₄precipitated in the iron oxide scale formed during the quenching and cooling process and quenching and tempering heat treatment is very small;As for the samples without oxide scale on the surface,there are more small pieces of pre-eutectoid Fe₃O₄in the oxide scale,and the eutectoid structure appears after the quenching and tempering treatment.