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研究连续退火时效温度对新型高铝600MPa级双相钢组织及性能的影响。拉伸性能研究发现,随着时效温度的降低,新型双相钢屈服强度降低、抗拉强度提高、加工硬化指数提高,同时屈服平台消失。金相分析发现,退火试样组织由铁素体+岛状弥散分布的第二相组成;随着时效温度的降低,第二相组织由马氏体+珠光体转变为单一的马氏体相。透视电镜分析发现,时效温度高时,第二相组织由由马氏体和细珠光体组成,且铁素体中的位错消失;随着时效温度的降低,第二相转变为单一马氏体相,且马氏体中存在明显的孪晶结构和层错结构,同时铁素体中的位错密度大大提高。结果表明,低温时效有助于新型高铝双相钢获得独特的微观组织结构从而确保了其优良的力学性能。
The effect of continuous annealing aging temperature on microstructure and properties of a new high-strength 600MPa dual-phase steel was studied. Tensile properties of the new dual-phase steel decreased with the aging temperature decreased, the tensile strength increased, the work hardening index increased, and the yield platform disappeared. Metallographic analysis showed that the microstructure of the annealed samples consisted of the second phase with ferrite + island-like dispersion. With the decrease of aging temperature, the second phase transformed from martensite to pearlite to martensite . It was found by TEM that when the aging temperature was high, the second phase consisted of martensite and fine pearlite, and the dislocations in the ferrite disappeared. As the aging temperature decreased, the second phase transformed into a single Markov In the martensite, there are obvious twins and faults, and the density of dislocations in the ferrite increases greatly. The results show that the low temperature aging helps to obtain the unique microstructure of the new high-aluminum dual-phase steel to ensure its excellent mechanical properties.