Comparative Studies On Corrosion Behavior Of 316L And Super Ferrite Stainless Steel In Medium And Low Temperature Geothermal Water Environment

Because of global warming and fossil energy shortages,geothermal energy,a green and low carbon alternative energy source,plays an irreplaceable role in improving the atmospheric environment and human living environment.For the typical geothermal environment,it is of great scientific and industrial significance to grasp the corrosion behavior of different types of stainless steel,and choose the right one.In the present work,316L and super ferritic stainless steel(B44660 and S44660)are chosen.Traditional electrochemical testing technology combined with advanced micro-area electrochemical testing,and the analysis of material surface are utilized to investigate the corrosion fouling behavior in geothermal environment of different temperatures and p H values,laying a theoretical foundation for the corrosion protection of stainless steel in geothermal water.According to the electrochemical polarization curve and impedance spectrum analysis,The corrosion rates of all the three stainless steels increases with increasing temperature.The corrosion resistance of 316L is better than that of S44660 and B44660.In addition,the corrosion rate in either acidic or alkaline environment is greater than those in neutral environments.In acidic environments,the corrosion resistance of 316L and S44660 is relatively close and superior to that of B44660.However,the corrosion resistance of all the three stainless steels is relatively close in neutral and alkaline environments.According to the weight loss experiment and micromorphology analysis,the corrosion rates of S44660,B44660 and 316L increase with increasing temperature in geothermal water environment.The corrosion type of S44660 is mainly uniform corrosion and a small amount of pitting corrosion,and the scale is re latively obvious.The corrosion type of B44660 is mainly pitting corrosion.The number of deep pit is very large,and the scale is serious.The corrosion type of 316L is mainly uniform corrosion and the scale is slight.The chemical composition of the scale product on the material surface is mainly Ca CO₃ and Mg CO₃,which are in the form of spheres and needles.According to the micro-area electrochemical experiment analysis,with the proceeding of corrosion,the average potential of the electrode surface of S44660 and 316L is negatively shifted,and the anode region reduces.The corrosion of anode region is obvious.As the geothermal water ambient temperature increases,the corrosion potential shifts negatively.