【摘要】 API SPEC5D标准规定的材料性能指标不能反映钻杆抵抗疲劳及腐蚀疲劳的性能。对4个厂家的S135钢级钻杆的材料进行了腐蚀疲劳寿命试验、拉伸性能试验及成分分析。试验结果表明,虽然4种钻杆的化学成分及材料性能都符合标准要求,且材料的拉伸强度基本相同,但腐蚀疲劳寿命相差很大。腐蚀疲劳断口观察及断裂机理分析表明,腐蚀疲劳裂纹扩展机理是阳极溶解与氢致开裂共存,氢致开裂加快了疲劳裂纹扩展。材料低倍组织酸洗检验、显微组织分析表明,4种钻杆的金属组织特别是低倍组织有明显差别。低倍组织反映了成分偏析程度、夹杂物含量及分布等。成分偏析及夹杂物导致材料的阳极溶解、特别是氢致开裂速度加快,所以是腐蚀疲劳寿命减少的主要原因。油田数据验证,钻杆材料的低倍组织酸洗检验可作为间接评定钻杆材料腐蚀疲劳性能的方法。更多还原

【Abstract】 The material requirements specified by API SPEC 5D could not show the ability of drill pipes in resisting fatigue and corrosion fatigue.The corrosion fatigue life,the tensile property and the chemical ingredient of drill pipes produced by four factories were tested.Although the chemical composition and property of materials conformed to meet the standard requirement,and the material strength of drill pipes from four factories were almost same,the corrosion fatigue life and fatigue mechanism of the materials for drill pipes from four factories were very different.The observation of corrosion fatigue fracture and analysis of crack mechanism indicated that the corrosion fatigue of the drill pipes was resulted from the anodic dissolution and hydrogen-induced crack together.The hydrogen-induced crack accelerated the fatigue crack progress.The material macrostructure was inspected by acid eroding method,and metallurgical microstructure was analyzed.The metallurgical microstructure,especially macrostructure of the drill pipes from 4 factories was also different.The metallurgical macrostructure showed the degree of metal chemical element segregation and the amount of inclusion which resulted in the decrease of corrosion fatigue life,due to acceleration of the anodic solution and hydrogen induced-crack of metal.The data of drill pipes in oilfields proved that the material macrostructure inspected by acid eroding method might assess indirectly the material property such as corrosion fatigue life of drill pipe.更多还原