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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H_2S环境里的应力腐蚀开裂敏感性。
The influences of manufacturing factors, structural factors and material ductility on corrosion fatigue resistance of sucker rod were investigated by means of microstructure analysis, fracture analysis, finite element simulation analysis, fatigue crack growth rate test and stress corrosion test. The results show that the manufacturing process tends to lead to the oxidative decarburization of the sucker rod steel surface and the deflection of the upsetting section, which has an adverse effect on the corrosion fatigue life of the sucker rod. The sucker rod structure causes the stress concentration in the upsetting section and the leading edge of the sucker rod, And the maximum stress always appears on the rod surface. The coupling of surface oxidative decarburization and stress concentration makes the sucker rod rapidly induce fatigue cracks in the corrosive environment; in the corrosive environment, increasing the sucker rod strength will lead to the increase of the fatigue crack growth rate, and the corrosion of the high-strength sucker rod Stress corrosion cracking will occur on fatigue crack growth curve. Reducing the strength of sucker rod and increasing the toughness of sucker rod can effectively reduce the sensitivity of sucker rod to stress corrosion cracking in H2S environment.