论文部分内容阅读
采用液氮蒸发低温处理设备对输电铁塔用Q345钢板进行不同温度的低温处理,采用光学显微镜对钢的显微组织进行观察,并对钢板拉伸、冲击力学性能进行检测,采用扫描电镜对冲击断口进行观察。结果表明,随着低温处理温度降低,Q345钢组织中碳化物的含量逐渐增加,带状组织形态消失,铁素体组织逐渐细化,至-50℃时组织完全均匀化,形成细小的珠光体+铁素体组织,碳化物在基体呈弥散分布;抗拉强度及屈服强度均大幅提高,伸长率逐渐下降,断面收缩率先缓慢减小,当温度低于-20℃时急剧下降;冲击功先缓慢下降,当处理温度达到-40°时冲击功急剧降低,纤维断面率先呈线性下降的趋势,当温度达到-50℃时急剧下降至10%左右,冲击结果表明Q345钢的50%FATT大约为-27℃。
Liquid nitrogen evaporation cryogenic treatment equipment for power transmission tower using Q345 steel at different temperatures of low temperature, the use of optical microscopy of the microstructure was observed, and steel tensile, impact mechanical properties were detected by scanning electron microscopy impact fracture Observe. The results show that with the decrease of the temperature, the content of carbides in Q345 steel gradually increases, the morphology of the ribbons disappears and the ferrite structure gradually becomes thinner. When the temperature is -50 ℃, the microstructure is completely homogenized, forming fine pearlite + Ferrite and carbides are dispersed in the matrix; the tensile strength and yield strength are greatly increased, the elongation is gradually decreased, the cross-sectional shrinkage rate first decreases slowly, sharply decreases when the temperature is lower than -20 ℃; impact energy The first drop of the impact strength of the Q345 steels first slowed down. When the temperature reached -40 °, the impact energy decreased sharply and the fiber cross-section decreased linearly first. When the temperature reached -50 ° C, the impact strength dropped sharply to about 10%. The impact results showed that 50% -27 ° C.