空冷高硅中碳低合金钢的组织与性能

Microstructure and properties of air cooled high silicon medium carbon low alloy steel

研究了高硅中碳低合金钢空冷态和空冷+回火态的显微组织和力学性能.试验钢在860℃保温0.5 h奥氏体化后空冷处理,随后分别在250℃和400℃保温1 h回火.结果表明:试验钢空冷后组织为贝氏体/马氏体和残余奥氏体的混合组织,硬度约为41 HRC;而250℃回火后组织变化不大,硬度明显升高,约为49 HRC,韧性明显增加,由44 J/cm2增加到66 J/cm2,抗拉强度、屈服强度和延伸率明显下降.回火温度进一步增加对力学性能影响不大.

The microstructures and mechanical properties of the high silicon medium carbon low alloy steels subjected to air cooling and tempering after air cooled were investigated.After austenized at 860 ℃ for 0.5 h,the testing steels were air cooled to ambient temperature,subsequently some of the samples were further tempered at 250 ℃ and 400 ℃ for 1h respectively.The experimental results show that the microstructure of testing steels subjected to air cooling is a mixed microstructures comprised of bainite/martensite plus retained austenite,and the hardness of testing steels is 41 HRC.While after tempered at 250 ℃,although the microstructure of testing steels is changed slightly,the hardness is increased to 49 HRC,the toughness is distinctly increased from 44 to 66 J/cm2,however the tensile strength,the yield strength and the elongation are markedly decreased.The further increase of tempering temperature has not large effect on mechanical properties.