Fracture Failure Analysis of Φ50.8mm Coiled Tubing

作者：Na Li, Li Xia Zhu, Cong Shen, Yao Rong Feng · 发表于：Materials science forum · 年份：2020 · DOI：10.4028/www.scientific.net/msf.993.1235 · 被引用次数：3 · 研究领域：Oil and Gas Production Techniques、Offshore Engineering and Technologies、Drilling and Well Engineering

The fractured coiled tubing of TS90 steel grade Φ50.8 mm ×3.96 mm in a certain oilfield was analyzed through macroscopic observation, magnetic powder inspection, physical and chemical properties testing, microstructure analysis and SEM analysis. The results showed that the coiled tubing fracture belonged to fatigue fracture and the fatigue crack originated from the area of cyclic friction on the outer surface of the tubing. The cyclic axial plastic stress of the tubing in service caused micro-cracks in the source area and finally led to fatigue fracture failure of the tubing.