Study on the effect of different cooling conditions on microstructural and mechanical properties of heat-treated T92 martensitic steel

Abstract

The T92 martensitic steel is utilized in thermal power plants because of its better mechanical properties, and it is needed to enhance the strength and improve the properties using heat treatment. The research aims to determine how the microstructure changes in T92 martensitic steel when normalized at 1000 °C for an hour and tempered at 760 °C for 2 hours using various cooling techniques, including air cooling, furnace cooling, and water quenching. It is characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), and optical microscopy (OM). Tensile strength, hardness and toughness measurements were also performed on the heat-treated T92 steel specimens. After tensile testing of heat-treated samples of T92 steel, the fracture surface was characterized using SEM to determine the fracture mode. The strength and hardness of T92 material increased with a normalizing of 1000 °C, whereas they decreased with a tempering of 760 °C. Compared to various material conditions, the tempering of 760 °C with air-cooled hold the tensile strength of 887 MPa, hardness of 267.42 HV and toughness of 135 J was shown to be the optimal combination.