Microstructure and Mechanical Properties of a Multi-element Low Alloy Bainitic Cast Steel

Low alloy bainitic cast steel to A3 as the main raw material,containing suitable Si,Mn,Cr,a sort of cheapness metal and trace amount of Mo and using rare earth(RE) to microalloying and modification,smelt in intermediate frequency furnace;Cast 10 mm× 10 mm× 55 mm without notched impact specimen in green sand molding.The sample could obtained meta-bainitic as matrix excellent performance alloy after heat treatment.The steel air-cooled after austenitic,and then drawing temper.The hardness and impact toughness were tested,and its microstructure and fracture morphology were observed by.electron metallography and scanning electron microscopy(SEM).Test results showed that a good mechanical performance(impact toughness≥240 J/cm2,hardness≥34 HRC) of bainite structure can be obtained by tempered at 300 ℃ for 2 h when it is cooled by air at 920 ℃×1 h.The results show that the microstructure consisting of meta-bainite and a few residual austenites can be obtained through the optimum quenching,The experiment proves this steel has a simple production process,less addition of valuable alloy and low production cost.It could substitute for quenched and tempered steel and increase economic performance.