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研究了等温处理对中碳超高强度弹簧钢组织与力学性能的影响。结果表明,在325~375℃等温可以获得无碳化物贝氏体/马氏体复相组织;奥氏体化温度对贝氏体/马氏体复相组织的影响很大,从875℃升高到930℃,强度升高,但其塑性、冲击韧性和断裂韧性显著降低。试验范围内,在875℃保温30 min,325℃等温120 s油淬后,在300℃进行回火处理2 h,可获得强韧性配合良好的贝氏体/马氏体复相组织,其断裂韧性KIC值为83MPa.m1/2,是相同强度水平下常规淬火回火马氏体组织的1.5倍。
The effect of isothermal treatment on the microstructure and mechanical properties of medium carbon super high strength spring steel was studied. The results show that the carbide-free bainite / martensite composite phase can be obtained at isothermal temperature of 325 ~ 375 ℃. The influence of austenitizing temperature on the microstructure of bainite / martensite is significant, from 875 ℃ High to 930 ℃, the intensity increased, but its plasticity, impact toughness and fracture toughness decreased significantly. Within the test range, the bainite / martensite duplex with good toughness and good toughness can be obtained by tempering at 300 ℃ for 30 min after holding at 875 ℃ for 30 min and at an isothermal temperature of 325 ℃ for 120 s Toughness KIC value of 83MPa.m1 / 2, is the same level of conventional quenching tempered martensite 1.5 times.