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采用Formastor-F热模拟试验机测定了一种含铜超低碳钢900℃未变形奥氏体0.2～100℃/s冷速下连续冷却转变曲线,观察分析不同冷速下的相变组织,并测定对应的维氏硬度。结果表明,不同冷速下,这种超低碳钢奥氏体稳定转变成贝氏体铁素体组织,冷却速度对实际晶粒度无显著影响,冷速在3℃/s以下,组织主要为准多边形贝氏体铁素体,且在基体上析出细小ε-Cu颗粒;冷速在5℃/s以上,组织主要为贝氏体型铁素体,硬度不发生显著变化。
The Formastor-F thermal simulation test machine was used to measure the continuous cooling transformation curve of undeformed austenite at 900 ℃ for 0.2 ~ 100 ℃ / s at 900 ℃. The phase transformation microstructure under different cooling rates was observed and analyzed. And the corresponding Vickers hardness was measured. The results show that the austenite of this kind of ultra-low carbon steel transforms into bainitic ferrite at different cooling rates. The cooling rate has no significant effect on the actual grain size. The cooling rate is below 3 ℃ / s, Is quasi-polygonal bainitic ferrite, and fine ε-Cu particles are precipitated on the substrate. The cooling rate is above 5 ℃ / s, the microstructure is mainly bainitic ferrite, and the hardness does not change significantly.