N80油套管钢在质量分数3.5%NaCl溶液中的冲蚀行为

采用失重法和电化学测试研究了N80油套管钢在质量分数为3.5%NaCl溶液中的冲蚀行为。结果表明:N80钢的质量损失速率随搅拌转速增加先保持不变再增大;相同时间冲蚀时N80钢的自腐蚀电流密度明显大于浸泡腐蚀时的;自腐蚀电流密度随浸泡时间的延长而增大,随冲蚀时间的延长先增大后减小,随溶氧量的增加而增大;冲蚀初期流体对N80钢的腐蚀作用占主导,中后期则以流体的冲击作用为主;随冲蚀时间延长,N80钢表面腐蚀产物增加,腐蚀坑边缘塑性变形程度增大,形状由圆形逐渐变为椭圆形,腐蚀速率减小;冲蚀1 h后的N80钢表面硬度低于未冲蚀的,冲蚀2 h后,N80钢表面由于形成硬化层,硬度高于未冲蚀的。

Erosion Behavior of N80 Oil Well Tube Steel in 3.5wt％ NaCl Solution

The erosion behavior of N80 oil well tube steel in 3.5%NaCl solution was studied by weightlessness method and electrochemical test.The results show that the mass loss rate of N80 steel unchanged and then increased with increasing the stirring speed.The self-corrosion current density of N80 steel during erosion was significantly greater than that during immersion corrosion under the same times.The self-corrosion current density increased with extensing the immersion time,increased and then decreased with extensing the erosion time,and increased with increasing the dissolved oxygen.The corrosion effect of fluid on N80 steel in the early stage of erosion was dominant,and the impact of fluid was dominant in the middle and late stages.With extensing the erosion time,the corrosion products on the surface of N80 steel increased,the degree of plastic deformation at the edge of the corrosion pit increased,shape of the corrosion pit gradually changed from circular to elliptical,and the corrosion rate decreased.The surface hardness of N80 steel after erosion for 1 h was lower than that of the uneroded,and after erosion for 2 h,the hardness of N80 steel was higher than that of the uneroded due to the formation of a hardened layer on the surface of N80 steel.