N80油套管钢CO_2腐蚀产物膜的力学性能

MECHANICAL PROPERTIES OF CO_2 CORROSION SCALE ON N80 WELL TUBE STEEL

N80油套管钢CO2腐蚀产物膜力学性能的测试结果表明,腐蚀产物膜的弹性模量与硬度从内层刮外层逐渐降低,弹性模量平均值为110 GPa.疏松的腐蚀产物膜内产生拉应力,应力大小随膜层的厚度增加而增加,腐蚀产物膜在试样表面稳定形成以后,内应力便趋于一个定值,大小约为46 MPa.外层府蚀产物膜的断裂应力、应变分别为55.6 MPa和5.06×10-4,小于内层膜断裂应力与应变(197.3-234.4 MPa和1.79×10-3-2.13×10-3).同样,内层膜与基体的粘附力要明显高于外层膜与内层膜。腐蚀产物膜内应力可以导致外层膜破裂.

The mechanical properties of CO2 corrosion scale formed on N80 well tube steel were measured. The results indicate that from inner layer to outer layer the hardness and elastic modulus of corrosion scale decrease gradually; the average elastic modulus is about 110 GPa. A tensile stress forms in porous CO2 corrosion scale, which increases with scale thickness and at last to a certain value when corrosion scale becomes stable. The maximum value of the inner stress is about 46 MPa. The fracture stress and fracture strain of outer layer are 55.6 MPa and 5.06 x 10(-4) respectively, and lower than those in the inner layer (197.3-234.4 MPa and 1.79 x 10(-3) - 2.13 x 10(-3)). Similarly the adhesion between inner layer and matrix is obviously higher than that between outer and inner layer. The inner stress of the corrosion scale could lead to cracking of corrosion scale.