Thermodynamic Analysis on Precipitated Phases in Low Activation Steel

Abstract

A type of low-carbon reduced activation ferritic/martensitic (RAFM) steel is designed.The microstructure and mechanical properties of tested steels prepared by different technologies were investigated by means of scanning electron microscope, transmission electron microscope and tensile test. The chemical composition of precipitations of tested steels are inspected by energy dispersive spectroscopy (EDS), meanwhile the law of precipitation phase of low carbon low activation FM steel was studied by thermodynamic calculations. The results show that the best mechanical properties are obtained by tempering at 750℃ for 1h after quenched from heating at 980℃ for 1h.The low carbon RAFM steel meeting performance standards can be produced. The precipitations are composed of M23C6 and MX.M23C6 carbide precipitates mainly in the process of below 950℃ rolling and heat treatment. However MX mainly precipitates in the process of rolling, and the secondary precipitation seldom occurs during the process of heat treatment and rapid cooling.

Keywords

• low activation steel
• microstructure
• thermodynamics
• precipitation behavior