材料期刊网

以降低P110级石油套管淬火冷却过程中的热应力和组织应力为目的，提出了水淬+空冷和水淬+空冷+水淬两种冷却方式。利用逐层钻孔法测试了不同工艺下的残余应力，分析了淬火组织特征和残余应力对裂纹产生和扩展的影响。结果表明：直接淬火工艺的淬火组织为板条马氏体和孪晶马氏体共存，且孪晶马氏体的含量较多。水淬+空冷和水淬+空冷+水淬两种工艺的淬火组织为板条马氏体、下贝氏体和不同程度的残余奥氏体，水淬+空冷+水淬工艺中还有少量孪晶马氏体。水淬+空冷、水淬+空冷+水淬两种冷却方式和直接淬火工艺相比，钢管内的切向和轴向残余应力均减小，从而易减小钢管的变形，以及降低和缓解了钢管内微裂纹的产生和扩展趋势。

In order to reduce the thermal stress and structural stress of P110 oil casing in the process of quench cooling, water quenching+air cooling and water quenching+air cooling+water quenching were proposed. The residual stresses of different processes were determined by incremental hole drilling method and the effect of microstructural features and residual stresses on crack formation and propagation was analysed. The results show that the quenching microstructure of direct quenching technology consists of lath and twin martensites, and the amount of the latter is more. The quenching microstructure of water quenching+air cooling and water quenching+air cooling+water quenching processes is composed of lath martensite, lower bainite and various amount of retained austenite. There are a few of twin martensite in the second technology. Compared to the direct quenching process, the tangential and axial stresses of proposed cooling methods are both decreased, then the deformation of steel pipe is reduced and the trend of microcrack formation and propagation is relieved.