Study on the Microstructure and Properties of Prehardened Plastic-Mould SWFT Steel for Big Section

摘要

In order to develop the prehardened plastic-mould SWFT steel for big section without quenching and tempering, the influence of carbon on the microstructure and corresponding hardness of steel under both air and sand cooling were investigated. It was demonstrated that when the carbon content of steels increased, the stability of overcooling austenite increased and the hardness difference decreased because of the decrease of bulk ferrite and the increase of bainite. The microstructure of No.8 steel under both air and sand cooling was mostly bainite and the hardness difference was less than 3HRC.And the No.8 steel had good machineability by the turning comparative experiment of No.8 steel and 45# steel. The prehardened plastic mould SWFT steel for big large section was produced successfully based on the experiment result.