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采用箱式电阻炉对输电铁塔用Q460钢板进行了不同工艺的正火和回火处理,采用光学显微镜对热处理试样显微组织进行了观察,并对拉伸、冲击、硬度进行了检测,研究了热处理对输电塔服役性能的影响。结果表明,钢材正火组织主要为珠光体+铁素体+贝氏体以及少量M-A组织,随正火温度升高,铁素体、珠光体含量逐渐减少,材料拉伸性能小幅提高,冲击功和硬度增加;随回火温度升高,M-A岛逐渐分解,贝氏体基体上析出较多颗粒状碳化物,钢的抗拉强度和屈服强度均降低,伸长率先小幅增加,在温度超过400℃后有所降低,硬度则几乎不变,860℃正火钢断面收缩率先降低后升高,冲击功先升高后降低,均在回火温度为300℃时达到极值,920℃正火钢断面收缩率和冲击功先升高后几乎保持不变。
The box-type resistance furnace was used to conduct normalizing and tempering of Q460 steel plate for power transmission tower. The microstructure of the heat-treated sample was observed with optical microscope, and the tensile, impact and hardness were examined. Effect of Heat Treatment on Service Performance of Transmission Tower. The results show that the normalized microstructure of steel is mainly composed of pearlite + ferrite + bainite and a small amount of MA. With the increase of normalizing temperature, the content of ferrite and pearlite gradually decreases, the tensile properties of the material increase slightly, And the hardness increased. With the increase of tempering temperature, the MA island gradually decomposed and more granular carbide precipitated on the bainite matrix, the tensile strength and yield strength of the steel decreased, the elongation increased slightly at the temperature of over 400 ℃, and the hardness is almost unchanged. The shrinkage of normal steel at 860 ℃ decreases first and then increases, and the impact energy increases first and then decreases, reaching the extreme value at the tempering temperature of 300 ℃, normalizing at 920 ℃ Steel section shrinkage and impact energy first increased almost unchanged.