Test method for exploring influence of Cu element on corrosion performance of steel rail

Abstract

The invention discloses a test method for exploring the influence of a Cu element on the corrosion performance of a steel rail, and belongs to the technical field of metal material corrosion. The method comprises the following steps: controlling a single variable, and changing the content of Cu in a steel rail to obtain steel rail samples with different Cu contents; the steel rail material is processed so as to meet the sample specifications required by different corrosion methods; and setting experimental parameters of periodic infiltration, salt spray corrosion, potentiodynamic polarization and electrochemical impedance, carrying out a series of steel rail corrosion tests to obtain various corrosion data, and exploring the influence of the Cu element on the corrosion performance of the steel rail.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material corrosion, and in particular relates to a test method for exploring the influence of Cu element on the corrosion performance of rails. Background Art

[0002] With the development of railway transportation, the service safety of rails has received more and more attention, and the corrosion resistance of rails is one of the most important factors to consider. Although Cu is added in trace amounts to rails, it significantly improves the environmental adaptability, mechanical properties and economic benefits of rails by optimizing the rust layer structure, strengthening the matrix and purifying the steel quality. It is one of the indispensable alloying elements for modern high-performance rails. During the corrosion process, Cu will be enriched on the surface of the steel, promoting the formation of a dense and stable rust layer, thereby effectively blocking the penetration of corrosive media and reducing the corrosion rate. 2+ Cu can participate in the formation of the rust layer, enhancing its adhesion and stability, making the rust layer more uniform and dense, and reducing the occurrence of localized corrosion. Cu can also combine with impurities such as S in the steel, reducing the harmful effects of inclusions such as MnS and reducing localized corrosion sensitivity. Therefore, it is necessary to use a variety of corrosion tests to explore the corrosion resistance of rails, including cyclic infiltration, salt spray corrosion, potentiodynamic polarization, and electrochemical impedance spectroscopy. Through a series of corrosion tests, we can determine the progress of the corrosion reaction, analyze the corrosion behavior, summarize the regular mechanisms, and explore the influence of Cu on the corrosion performance of rails.

[0003] Cyclic immersion testing is a highly effective method for assessing the corrosion resistance of materials by simulating alternating dry-wet environments. This method closely replicates diverse corrosion scenarios, such as those found in marine atmospheres and industrial areas. Compared to static immersion, it better reflects real-world operating conditions and improves data reliability. The dry-wet cycle accelerates the corrosion process. During the wet phase, the electrolyte causes electrochemical corrosion, while during the dry phase, salt concentration triggers chemical attack. This dual effect significantly shortens the test cycle and is more efficient than traditional salt spray testing. Salt spray corrosion testing is a classic method for evaluating material corrosion resistance. By continuously spraying an atomized sodium chloride solution to simulate marine atmosphere or saline industrial environments, it can rapidly induce uniform or localized corrosion on metal surfaces, significantly accelerating the corrosion process and far exceeding natural exposure. Potentiodynamic polarization testing, by applying a potential sweep, quickly generates polarization curves for materials, allowing for the rapid determination of key parameters such as corrosion current density and corrosion potential, and assessing the corrosion resistance of materials. It is a commonly used electrochemical method for evaluating metal corrosion behavior. The high-frequency region of the electrochemical impedance spectroscopy (EIS) reflects the capacitance / resistance characteristics of surface films or coatings, while the low-frequency region characterizes the corrosion reaction kinetics, providing comprehensive interface information. By fitting an equivalent circuit, parameters such as polarization resistance and double-layer capacitance can be accurately calculated, quantifying the corrosion rate and protective effect. This method provides a systematic experimental approach for exploring the influence of Cu on rail corrosion performance. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a test method for exploring the influence of Cu element on the corrosion performance of rails.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a test method for exploring the influence of Cu element on the corrosion performance of rails, comprising:

[0007] By controlling a single variable and changing the Cu content in the rail, rail specimens with varying Cu content were obtained. The rail material was processed to meet the specimen specifications required by different corrosion methods. A series of rail corrosion tests were conducted using parameters for cyclic infiltration, salt spray corrosion, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) to obtain various corrosion data and explore the influence of Cu on the corrosion performance of the rail.

[0008] Furthermore, the rail corrosion weight loss is obtained and the rail corrosion weight loss rate is calculated.

[0009] Furthermore, the mass loss of the rails in different time periods is obtained.

[0010] Furthermore, the self-corrosion potential and self-corrosion current density are obtained by using potentiodynamic polarization.

[0011] Furthermore, the Bode plot and Nyquist plot were obtained using electrochemical impedance spectroscopy.

[0012] Furthermore, a 3.5% by mass NaCl solution was selected as the corrosion solution to simulate atmospheric corrosion.

[0013] Furthermore, the rails were subjected to a salt spray corrosion test in a 3.5% NaCl solution for 6 h, 12 h, 72 h, 168 h, 240 h, and 480 h, respectively, and 6 sets of mass loss data were obtained for each group.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects:

[0015] The method of the present invention obtains various corrosion parameters through periodic infiltration, salt spray corrosion, dynamic potential polarization, electrochemical impedance spectroscopy, etc., and explores the influence of the Cu element on the corrosion performance of the rail. With the increase of Cu content, the self-corrosion potential of the rail gradually increases, the self-corrosion current density gradually decreases, and the corrosion performance of the rail is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] Figure 1 This is the Tafel comparison diagram of the electrochemical test potentiodynamic polarization;

[0018] Figure 2This is a comparison chart of electrochemical test impedance. DETAILED DESCRIPTION

[0019] The present invention uses cyclic immersion, salt spray corrosion, potentiodynamic polarization, and electrochemical impedance spectroscopy to obtain various corrosion parameters and explore the effect of Cu on the corrosion performance of rails. Those skilled in the art will also understand that the present invention is not limited to rails and is also applicable to the corrosion of other metals.

[0020] Using a small furnace test, 0.1% and 0.2% Cu were added to U75V rails, respectively, to obtain three groups of parallel samples, including ordinary U75V rail 1#, U75V rail 2# with 0.1% Cu addition, and U75V rail 3# with 0.2% Cu addition. Various corrosion tests were performed to investigate the effect of Cu on the corrosion performance of rails.

[0021] Three sets of rails were subjected to cyclic immersion tests in a 3.5% NaCl solution at a test chamber temperature of 45°C, a humidity of 70%, and a baking zone temperature of 70°C. The cyclic immersion instrument was operated for 72 hours. The rail corrosion weight loss was obtained, and the rail corrosion weight loss rate was calculated (Table 1). The conclusion is that adding Cu improves the corrosion resistance of rails, and that the rail corrosion weight loss and weight loss rate decrease with increasing Cu content.

[0022] Three rail groups were subjected to salt spray corrosion tests in a 3.5% NaCl solution for 6, 12, 72, 168, 240, and 480 hours, respectively. Six sets of mass loss data were obtained for each group, as shown in Table 2. The mass loss increased approximately linearly with increasing test time. At the same time, the higher the Cu content in the rail, the lower the mass loss of the sample during the salt spray test.

[0023] Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were performed on three rail groups in 3.5% NaCl solution. Two replicates were used for each of the 1#, 2#, and 3# rail groups. The potential range was set based on the open circuit potential ±1 V. The Tafel comparisons of the potential polarizations for rails 1-1, 1-2, 2-1, 2-2, 3-1, and 3-2 were obtained. Figure 1 The comparison of the three groups of electrochemical test impedance is shown in Figure 2 Basic electrochemical parameters such as corrosion potential and corrosion current density were obtained using potentiodynamic polarization experiments, and then compared and analyzed (see Table 3). With increasing Cu content, the corrosion potential of the rail gradually increased, the corrosion current density gradually decreased, and the corrosion performance of the rail improved.

[0024] Table 1 Comparison of corrosion parameters in cyclic immersion test

[0025] serial number <![CDATA[Weight loss due to corrosion (g / m 2 )]]> <![CDATA[Corrosion weight loss rate (g / m 2 / h)]]> Ordinary U75V rail 1# 407 5.65 Add 0.1% CuU75V rail 2# 310 4.30 Add 0.2% CuU75V rail 3# 257 3.57

[0026] Table 2 Mass loss of samples in salt spray test g / m 2

[0027] serial number 6h 24h 72h 168h 240h 480h Ordinary U75V rail 1# 5.2 31.9 118.7 308.2 408.5 1077.9 Add 0.1% CuU75V rail 2# 12.6 30.5 90.5 199.9 342.8 890.5 Add 0.2% CuU75V rail 3# 14.0 33.3 96.0 217.4 328.9 779.7

[0028] Table 3 Comparison of self-corrosion parameters in electrochemical tests

[0029]

[0030] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A test method for exploring the influence of Cu element on rail corrosion performance, characterized in that: include: By controlling a single variable and changing the Cu content in the rail, rail specimens with varying Cu content were obtained. The rail material was processed to meet the specimen specifications required by different corrosion methods. A series of rail corrosion tests were conducted using parameters for cyclic infiltration, salt spray corrosion, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) to obtain various corrosion data and explore the influence of Cu on the corrosion performance of the rail.

2. The test method for investigating the influence of Cu element on rail corrosion performance according to claim 1, characterized in that: Obtain the rail corrosion weight loss and calculate the rail corrosion weight loss rate.

3. The test method for investigating the influence of Cu element on rail corrosion performance according to claim 1, characterized in that: Obtain the mass loss of the rail at different time periods.

4. The test method for investigating the influence of Cu element on rail corrosion performance according to claim 1, characterized in that: The self-corrosion potential and self-corrosion current density are obtained by using potentiodynamic polarization.

5. The test method for investigating the influence of Cu element on rail corrosion performance according to claim 1, characterized in that: The Bode and Nyquist plots were obtained using electrochemical impedance spectroscopy.

6. The test method for investigating the influence of Cu element on rail corrosion performance according to claim 1, characterized in that: The corrosion solution was selected as a 3.5% by mass NaCl solution to simulate atmospheric corrosion.

7. The test method for investigating the influence of Cu element on rail corrosion performance according to claim 1, characterized in that: The rails were subjected to salt spray corrosion tests in 3.5% NaCl solution for 6 h, 12 h, 72 h, 168 h, 240 h, and 480 h, respectively, and 6 sets of mass loss data were obtained for each group.

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