石油膨胀套管的力学性能及膨胀后的残余应力

Mechanical Properties of Expansion Casing and Residual Stress after Expansion

针对选用的X52石油膨胀套管,通过不同的热处理工艺进一步改善其膨胀性能,研究了膨胀加工前后材料性能的变化规律.对于经扩径膨胀率达20%的管材,使用应力释放法测量了膨胀前后内外壁及焊缝熔合区、热影响区的轴向和环向残余应力.结果表明:经扩径膨胀后,管外壁的轴向和环向残余应力均为残余压应力,焊缝熔合区和热影响区的残余应力由拉应力向压应力转化,其中轴向残余应力变化幅度较大;管内壁膨胀后轴向与环向的残余应力均为残余拉应力.另外,对于不同膨胀率下力学性能与残余应力之间的关系中呈现的异常现象也进行了分析.

The expansion properties of X52 pipe were improved by heat treatment process,and the performance difference before and after expansion was investigated. For pipes with diameter expansion up to 20%,the axial and circumferential residual stresses on inside and outside walls,weld fusion zone and heat-affected zone were measured by the stress releasing method. The results show that both the axial and circumferential residual stresses on the outside wall of the pipe are compressive after expansion,and in the weld fusion zone and weld heat affected zone the residual stress varies from tensile to compressive,especially for the axial residual stress. On the inside wall,residual tensile stress appears in both directions after expansion. In addition,the abnormal relationship of the mechanical properties and residual stress under different expansion is analyzed.