Effect of cerium addition on microstructure and mechanical properties of as-cast high grade knives steel

The carbides and mechanical properties of as-cast high grade knives steel with and without cerium(Ce)addition were studied.The as-cast microstructure of the steel,the size of carbide precipitation,carbide morphology,and mechanical properties were systematically studied through optical microscopy,scanning electron microscopy,and X-ray diffraction.Besides,through the Equilib module of the FactSage thermodynamics software,the changes in the precipitation type of the inclusions with Ce during the solidification of the steel were calculated.The results indicate that the rare earth Ce is added into the steel to refine the as-cast microstructure of the steel.The types of inclusions in the steel are changed by the addition of Ce.The precipitated carbide morphology changes from a complex rod shape to a relatively single lamellar shape.The rare earth inclusions formed in steel by a moderate addition of Ce can be severed as the core of heterogeneous nucleation of carbides,which reduce the size of carbide precipitation,promote the uniform distribution of carbide in the as-cast steel,and improve the mechanical properties of the as-cast high grade knives steel.

Wetting and corrosion behavior between magnesia-carbon refractory and converter slags with different MgO contents

The influence of MgO content in slag on wetting and corrosion behavior between slag and MgO–C refractory was investigated.It can be known from the high-temperature wetting experiment that as the MgO content in the slag increases,the final contact angle between the slag and the MgO–C refractory gradually increases and the penetration depth of the slag into the refractory gradually decreases from 60.54μm(when the MgO content is 8%)to 28.11μm(when the MgO content is 12%).The CaO and SiO_(2)in the slag penetrate into the MgO–C refractory along the pores or surface cracks formed by carbon oxidation and react with MgO to generate a large amount of low-melting compound CaO–MgO–SiO_(2),which accelerates the corrosion of the refractory.As the MgO content in slag increases,the viscosity of the slag increases and the fluidity becomes worse,so that the mass transfer and diffusion of molecules or ions in the slag are weakened.In addition,the increase in MgO reduces the activity of FeO in the slag,which inhibits the interfacial chemical reaction,thereby weakening the wetting effect caused by the reaction.