N80钢级HFW套管的研发

研究了N80-1和N80-Q两种交货状态下HFW套管的力学性能、微观组织、残余应力以及沟槽腐蚀性能。研究发现，N80-1组织为铁素体、珠光体及少量贝氏体，N80-Q组织主要是回火索氏体，且N80-1焊缝中心有一明显沿纵向的金属流线，而N80-Q金属流线宽度变窄，而且模糊不清。通过TEM观测，N80-1焊缝附近母材区珠光体的片层结构完整清晰，而焊缝区的珠光体片短小、且杂乱无章，这种微观组织必然对应较高的残余应力。N80-1 HFW焊管宏观残余应力达到235～258 MPa，而N80-Q残余应力很小，整管热处理可以有效地消除焊管残余应力，但增加了生产成本。随着加载应力的增大，沟槽腐蚀敏感性线性增大。

Development of N80 Grade HFW Casing

In this article,it studied the mechanical properties,microstructure,residual stress,and grooving corrosion performance of HFW casing under N80-1 and N80-Q delivery conditions.The result indicated that the structure of N80-1 consist of ferrite,pearlite a little bainite,the structure of N80-Q is mainly tempered sorbite.A longitudinal metal flow line in N80-1 weld center was found obviously,while the width of N80-Q metal flow line is narrower and not clear.It found the lamellar structure of pearlite in pipe body nearby N80-1 weld is complete and clear,while the pearlite in weld is small and disorderly,so this kind of microstructure match along with the higher residual stress.The residual stress value of N80-1 HFW reach 235～258 MPa,while the residual stress value of N80-Q is very low,the whole pipe heat treatment can effectively eliminate welded pipe residual stress,but increase production cost.The grooving corrosion sensitivity linearity increases with loading stress increasing.