Research On Corrosion Resistance Of Nuclear Power Plant Structural Materials In Normal Temperature Environment

The use of high-quality and high-efficiency nuclear power energy is of great significance to effectively promoting the transformation of my country's energy structure.Ensuring the safe operation of nuclear power plants is the foundation and focus of nuclear power development.Since the structural materials of nuclear power plants are extremely susceptible to corrosion in the relevant water environment and affect the safe operation of nuclear power plants,it is particularly important to conduct in-depth research on the corrosion behavior of these equipment materials.Therefore,this article focuses on the nuclear power plant with the highest utilization rate in China,and selects low-alloy steel 16MND5 and SA508.3,welded stainless steel E308 L and its welded parts,and welded nickel-based alloy ERNi Cr Fe-which are commonly used structural materials in nuclear power plants.7A and its welded parts,through the electrochemical test and other experimental methods,the corrosion resistance of the material under normal temperature environment has been studied and evaluated,and quantified corrosion performance data have been formed,which provides an experimental basis for the localized selection and protection of nuclear power industry.The conclusions are as follows:(1)Through the immersion experiment and the neutral salt spray experiment,the low alloy steel 16MND5 and SA508.3 were observed on the macroscopic morphology of corrosion.The two materials have a fast corrosion rate and poor corrosion resistance,but from the metallographic structure and SEM corrosion morphology Compared with the above,the corrosion resistance of SA508.3 is better than that of 16MND5.Electrochemical test results also show that 16MND5 is more corrosive than SA508.3.(2)Through the immersion experiment and neutral salt spray experiment,the macro-morphology of the weld stainless steel E308 L and the weld nickel-based alloy ERNi Cr Fe-7A were observed.The two materials showed good corrosion resistance in the two sets of experiments.,No corrosion was found on the macroscopic morphology.According to the electrochemical test of E308 L and ERNi Cr Fe-7A,the corrosion resistance of ERNi Cr Fe-7A is better than that of E308 L.(3)The fitting results of polarization curves of E308 L welding parts in 3.5% Na Cl solution show that the polarization curves of the three areas are close,and the corrosion resistance of the three different areas of the welding parts is relatively strong.Relatively speaking,the corrosion current density of the base metal Z2CND18-12 N is the largest,followed by the heat-affected zone,and the corrosion current density of the weld metal E308 L is the smallest,indicating that the base metal has the strongest corrosion resistance and the weld has the worst corrosion resistance..The EIS test results show that the resistance value of the base metal is the largest,which also shows that the corrosion resistance of the base metal is the strongest among the three areas of the weldment.(4)The polarization curve test results of three regions of ERNi Cr Fe-7A welded parts in3.5% Na Cl solution show that the welded parts can form a passivation film in the solution,and the corrosion current density is very low.The base material 316 L has the strongest corrosion resistance,followed by the weld nickel-based alloy ERNi Cr Fe-7A,and the heat-affected zone has the weakest corrosion resistance.In the EIS results of the three regions,the resistance values of the base metal and the weld are close,while the resistance value of the heat-affected zone is the smallest,which also shows that the corrosion resistance of the heat-affected zone is the worst,which is consistent with the polarization curve.