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利用淬火变形膨胀仪(DIL805A),结合金相显微分析和显微硬度测量,研究了冷却速率(0.2~75℃/s)对10B21冷镦钢过冷奥氏体连续冷却转变的影响。用光学显微镜和扫描电镜观察试验钢在不同冷却条件下的显微组织,研究了不同冷速对钢的组织和硬度的影响,绘制了其CCT曲线。结果表明,10B21钢连续冷却过程中,冷速为0.2~15℃/s时,组织为铁素体、珠光体;当冷速≥20℃/s时,开始出现羽毛状贝氏体;冷速为45~60℃/s时,主要是羽毛状的上贝氏体;冷速为75℃/s时,主要是板条马氏体。
The effects of cooling rate (0.2 ~ 75 ℃ / s) on the continuous cooling transformation of the subcooled austenite of 10B21 cold heading steel were studied by means of quenching and deformation dilatometer (DIL805A), metallographic analysis and microhardness measurement. The microstructure of the test steel under different cooling conditions was observed by optical microscope and scanning electron microscope. The influence of different cooling rates on the microstructure and hardness of the steel was studied and the CCT curve was drawn. The results show that when the cooling rate is 0.2 ~ 15 ℃ / s, the microstructure of the 10B21 steel is ferrite and pearlite. When the cooling rate is more than or equal to 20 ℃ / s, feathering bainite begins to appear. The cooling rate For 45 ~ 60 ℃ / s, the main feathery upper bainite; cooling rate of 75 ℃ / s, the main lath martensite.