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摘要采用模拟“I 8—8不锈钢/c卜”体系腐蚀裂缝形成过程不同阶段的闭塞区溶液.以电化学方法研究了1.8—8不锈钢加载到屈服后在这些溶液中的腐蚀行为。结粜表明:当溶液pH值低于一临界值(约】.8)后受力试样的腐蚀开始加速.而不受力试样加速腐蚀的临界pH值则较低.约为1.5。低于临界值,受力与未受力试样的商蚀电位都从约一200mY.SCE(位于钝化区)突然下降到一400mY左右(处于活化区).表明钝化膜完全破裂。受力屈服后合金的钝化能力变差。将上述闭塞区溶液中测得的动电位极化曲线上的特征电位.电位一时间曲线上所得到的稳定开路电位.放氢平衡线和免蚀线.以及闭塞区腐蚀和放氢动力学曲线等叠加绘制而成的实验电位一pH图,能解释应力腐蚀裂缝内的热力学和动力学行为。
Abstract The occlusion zone solution of different stages of the crack formation process was simulated by simulating “I 8-8 stainless steel / c Bu” system.The corrosion behavior of 1.8-8 stainless steel in these solutions after loading was studied electrochemically. Results show that when the pH value of solution is lower than a critical value (about 8), the corrosion of stressed specimen begins to accelerate, while the critical pH value of accelerated sample without force is lower, about 1.5. Below the critical value, the corrosion potential of both the stressed and unstressed samples suddenly drops from about 200 mSCE (in the passivation region) to about 400 mY (in the activation region), indicating that the passivation film is completely cracked. Passivation yield alloy passivation ability worsened. The characteristic potentials on the potentiodynamic polarization curve measured in the solution of the occluded zone, the stable open circuit potentials obtained on the time curve of potentials, the equilibrium line of hydrogen evolution and the corrosion-free line, and the kinetic curves of corrosion and hydrogen evolution in the occluded zone Such as a superimposed plot of experimental potential-pH diagram to explain the thermomechanical and dynamic behavior of stress corrosion cracking.