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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 the tissue stress during the quench cooling process of P110 oil casing, two cooling methods, water quenching + air cooling and water quenching + air cooling + water quenching, are proposed. The residual stress under different processes was tested by layer-by-layer drilling method. The effect of quenched structure and residual stress on the crack initiation and propagation was analyzed. The results show that the quenched microstructure of the direct quenching is that the lath martensite and twin martensite coexist, and the content of twinned martensite is higher. Water quenching + air cooling and water quenching + air cooling + water quenching two kinds of technology quenching organizations lath martensite, bainite and different degrees of residual austenite, water quenching + air cooling + water quenching process there is a small amount Twinning martensite. Water quenching + air cooling, water quenching + air cooling + water quenching two cooling methods and direct quenching process compared to the steel pipe tangential and axial residual stress are reduced, thus easily reducing the deformation of the pipe, and reduce and alleviate Micro-cracks in steel pipe production and expansion trend.