铜对中碳硅锰钢连续冷却相变的影响

 为了探索含铜中碳硅锰钢连续冷却转变过程中的相变规律，采用DIL805L型膨胀仪研究了铜对中碳硅锰钢连续冷却过程中显微组织和硬度的影响，借助高分辨透射电镜研究了连续冷却过程中含铜相的析出行为。结果表明，在中碳硅锰钢的连续冷却过程中，铜的加入使得铁素体转变的孕育期延长，且降低贝氏体和马氏体开始转变温度。富铜颗粒在铁素体中弥散析出，细化连续相变组织。冷却速度小于21 ℃/s时，含铜中碳硅锰钢由于富铜颗粒析出以及贝氏体和马氏体组织增加引起显微硬度增加。当冷却速度大于21 ℃/s时，铜反而会降低钢中贝氏体和马氏体组织的显微硬度。

Effect of Cu on continuous cooling transformation of medium carbon Si-Mn steel

In order to understand phase transformation of Cu-containing medium carbon Si-Mn steel，the effect of Cu on microstructures and micro-hardness of medium carbon Si-Mn steel at different cooling rates were investigated by a DIL805L thermal dilatometer. The Cu-rich precipitates were analyzed by high resolution transmission electron microscope. The results show that Cu could prolong bainite ncubation period， reduce bainite and martensite starting transformation temperature. During continuous cooling transformation，The Cu-rich particles dispersive precipitate in the ferrite and refine ferrite grain. The micro-hardness of copper bearing medium carbon Si-Mn steel increased with the cooling rate increase when the cooling rate was lower than 21 ℃/s. The content of Cu-rich particles increased with the increase of cooling rate，meanwhile the bainite and martensite also increased. Instead，Cu can lower the micro-hardness of bainite and martensite in the steel when the cooling rate was higher than 21 ℃/s.