通过显微组织分析、断口分析、有限元模拟分析、疲劳裂纹扩展速率测试和应力腐蚀试验研究制造因素、结构因素和材料强塑性对抽油杆腐蚀疲劳抗力的影响.结果表明,制造环节易导致抽油杆钢表面氧化脱碳以及镦粗段偏斜从而对抽油杆腐蚀疲劳寿命产生不利影响;抽油杆结构导致抽油杆镦粗段及前沿存在应力集中,且最大应力总是出现在杆体表面.表面氧化脱碳与应力集中的耦合作用使得抽油杆在腐蚀环境中快速诱发疲劳裂纹;在腐蚀环境中,提高抽油杆强度会导致疲劳裂纹扩展速率的增加,并且高强度抽油杆的腐蚀疲劳裂纹扩展曲线上会出现应力腐蚀平台;降低抽油杆的强度,提高抽油杆的韧性可以有效降低抽油杆在H2S环境里的应力腐蚀开裂敏感性.
Influence factors of manufacturing process,geometry configuration and the matching between strength and plasticity on corrosion fatigue resistance of sucker rods steel were studied by means of microstructure analysis,fracture analysis,finite element analysis,the testing of fatigue crack growth rate and stress corrosion testing.The results show that the surface decarburization and deflecting of upsetting section are easily formed during the manufacturing process;the geometry configuration of the sucker rod can cause the obvious stress concentration in the upsetting section and its cutting edge.The coupling of the surface decarburization and stress concentration results in a rapid inducing of fatigue crack in the corrosion environment.The corrosion fatigue crack growth rate increases with the increasing of strength of the sucker rod,moreover the curve of corrosion fatigue crack growth of high strength sucker rod has obvious stress corrosion platforms.The stress corrosion sensitivity of sucker rod steel can be effectively reduced by reducing the strength and improving toughness in the corrosion environment containing hydrogen sulfide.
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