模拟点腐蚀多孔的两种油套管钢的拉伸性能

Tensile Characteristics of Two Oil Well Steels with Simulative Porosity

根据发生点腐蚀的油气管线基体呈现出点蚀坑的多孔特点,选用了两种常用的油套管钢N80和P110,通过计算机产生随机数确定点蚀坑的位置,利用小钻头打孔的方法模拟其基体多孔特征进行拉伸试验,测得其弹性模量E、屈服强度σ0.2和抗拉强度bσ,将前二者的理论公式进行修正,给出了两种多孔钢的bσ与孔隙率Φ的函数关系式。结果表明,随着材料Φ的增加,测得E、0σ.2和bσ均下降,且下降趋势逐渐减缓;E的测量值和理论计算值吻合,P110钢比N80钢符合得更好;0σ.2的测量值随着Φ的增加而递减,但衰减速率略快于理论预测;bσ的变化与屈服强度相似,在较大Φ时递减趋于缓慢。

According to characteristics of pitting corrosion on oil well tube in corrosion environment, which distributed randomly on pipeline surface and were various in its depth one another, the locations of simulated pitting corrosion on the surfaces of oil well steels N80 and P110 were confirmed by the random numbers produced in computer to measure elastic modulus, yielding strength and strength limit of porose materials by tension tests, and the former two theoretical formula were modified, and the calculated formula of strength limits were proposed for two steels. The test results show that the elastic modulus, yielding strength and strength limit of two porose materials decrease with increase of its porosity, and the changing trend becomes slow gradually. The testing results of elastic modulus of two steels with porosity are lower than those of the theoretical values, and the dispersion of P110 steel is less than that of N80 steel. The testing values of their yielding strength decrease evidently with porosity and are much less than the theoretical values. The testing values and their aver age of strength limits decrease also evidently with porosity as those of yielding strength, but their varying is apt to decrease within much porosity.