| LI Bin,ZENG De-zhi,SHI Tai-he,LIU Fei,YU Zhi-ming.Bending Fatigue Properties of S135 Drill Pipe Steel After Corrosion[J],45(3):17-23 |
| Bending Fatigue Properties of S135 Drill Pipe Steel After Corrosion |
| Received:December 01, 2015 Revised:March 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.03.004 |
| KeyWord:S135 drill pipe steel bending fatigue test pitting stress concentration fracture analysis fatigue fracture |
| Author | Institution |
| LI Bin |
State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University,Chengdu , China |
| ZENG De-zhi |
State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University,Chengdu , China |
| SHI Tai-he |
State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University,Chengdu , China |
| LIU Fei |
Petroleum Engineering Technology Research Institute of Sinopec, Beijing , China |
| YU Zhi-ming |
State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University,Chengdu , China |
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| Abstract: |
| Objective Study the impact of organic salt drilling fluid on corrosion and fatigue properties of S135 drill pipe. Methods Simulated organic salt drilling fluid corrosive condition by using autoclave and pre-corroded fatigue samples and measured the sample surface corrosion condition. Maked fatigue test with pre-corrosion samples and normal samples by using PQ-6 bending fatigue test machine under different stress conditions. Calculated fatigue strength under different reliability and drew the P-S-N curve. The surface of samples and fracture were observed by stereomicroscope and scanning electronmicroscopy(SEM).We analysed the influence of corrosion and the fatigue fracture mechanism. Results The surface of the sample had many pits after corrosion and the depth of corrosion pits were about 0.4 ~ 0.7mm; the fatigue strength of normal samples was 553MPa, the fatigue fracture surface had one crack source; the fatigue strength of pre-corrosion samples was 409MPa, the fatigue fracture surface had several crack sources; the fatigue corrosion cracking sensitivity index was 26%. Conclusion The sample surface pitted serious after corrosion in high temperature and pressure environment of organic salt drilling fluid. It had many crack sources and existed stress concentration at the bottom of corrosion pits which caused crack sources. The growth of crack sources at the same time accelerated crack propagation and reduced fatigue strength of S135 drill pipesteel finally. |
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