## 6 Conclusions  
There are many reasons for stray currents, most of which are related to the functioning of the electrified tracks, UHV transmission lines, and cathodic protection systems themselves. Metal components in infrastructure near high-speed railway stations and UHV transmission lines are particularly vulnerable to corrosion from stray currents. Based on this, this paper compared the corrosion mechanisms and interference characteristics of DC and AC stray currents. DC stray current corrosion, on the basis of electrochemical corrosion, further lowers the potential of the pipeline's cathodic region, making the pipeline metal more susceptible to losing electrons, which accelerates the corrosion rate of the pipeline. DC stray current interference is a dynamic disturbance where asymmetric current distribution and poor grounding of the power supply system increase the stray current density, further accelerating corrosion. As for the corrosion mechanism of AC stray current, scholars have not reached a consensus; however, the theories supported include the rectification model, alkalization mechanism, and AC depolarization theory. However, it remains fundamentally an electrochemical corrosion process, with the positive and negative half-cycles of the alternating current continuously influencing each other, resulting in ongoing corrosion of the pipeline metal. In terms of corrosion morphology, the corrosion damage caused by DC stray currents is generally more severe than that caused by AC stray currents. The corrosion appearance due to DC interference is a continuous bubble-shaped round pit, mostly pitting. For AC stray current corrosion, as the current density increases, the corrosion morphology gradually transitions from uniform corrosion to localized pitting corrosion. In terms of measurement methods, DC stray current can be measured using a potentiometer, current recorder, and SCM (stray current mapper). Among these, the SCM method offers higher measurement accuracy. In comparison to DC stray current measurements, the standards for measuring AC stray current are not unified. Typically, AC current density is used as the primary indicator of current interference, while AC voltage serves as an auxiliary evaluation criterion. AC current meters can be used to measure the AC current and its density. In terms of influencing factors, they can primarily be divided into environmental and electrical factors. In addition, factors such as stress, the effectiveness of protective measures, and pipeline materials also play a role. In response to the corrosion damage caused by stray currents on underground pipelines, this paper proposes three corrosion prevention measures: the use of corrosion-resistant coatings, cathodic protection, and internal corrosion protection technologies for pipelines. Among these, corrosion-resistant coatings serve as a physical barrier. Additionally, some coatings contain corrosion inhibitors, which are released when corrosive media penetrate, providing further corrosion protection. Furthermore, some coatings achieve protection for pipeline materials through sacrificial anode cathodic protection. Catholic protection, as one of the most widely used pipeline corrosion prevention methods, is typically combined with corrosion-resistant coatings for enhanced protection. The sacrificial anode-cathode protection, impressed current method of cathodic protection, and drainage protection of cathodic protection are three of the most common methods. The former is suitable for smaller structures where external power sources are not easily available, while the latter two methods are applicable in environments with more complex corrosion and denser stray currents. In terms of internal corrosion protection technologies, both corrosion inhibitors and internal coating technologies can effectively suppress pipeline corrosion. In recent years, composite pipe technology has received increasing research and application attention.