Corrosion Behavior of Weathering Steel for Railway Freight Cars under Interaction of Cu-P-Cr-Ni AITranslate
Abstract AITranslate
With the continuous increase of freight volume in heavy railway，the demand for the corrosion resistance of railway freight car body materials has increased. Q450NQR1 and Q345NQR2 are the primary materials used in railway freight car bodies，however，through our investigations，it has been found that the amount of corrosion-induced damage in the actual use of these two materials remains unacceptably high. Therefore，in this paper，the corrosion behavior of Q450NQR1 and Q345NQR2 weathering steels was studied，using electrochemical workstation，cyclic immersion corrosion testing machine，scanning electron microscopy （SEM），X-ray diffraction （XRD），and electron probe microanalysis （EPMA），aiming to explore the reasons for the interaction between alloying elements that affect corrosion resistance and play a crucial role in enhancing the corrosion resistance of weathering steels. The electrochemical corrosion tests of the two weathering steels showed that Q345NQR2 had better electrochemical corrosion performance compared to Q450NQR1，due to the content of Cu，P，Cr and Ni in Q345NQR2 was higher than that in Q450NQR1. The corrosion behavior of Q450NQR1 and Q345NQR2 was also investigated after 72 h of accelerated corrosion in an industrial atmospheric environment，and the results showed that the weight loss rate of Q345NQR2 was 1.264 g·m−2·h−1，higher than that of 1.139 g·m−2·h−1 for Q450NQR1，indicating a poorer corrosion resistance，contrary to the results of electrochemical corrosion. The macroscopic morphology of the sample surface revealed a rougher rust layer for Q345NQR2 compared to Q450NQR1. SEM images of the surface morphology further revealed the presence of corrosion pits on the surface of Q345NQR2，while the rust layer surface of Q450NQR1 was smoother and denser. The corrosion products of both weathering steels were found to be γ-Fe2O3/Fe3O4，α-FeOOH and γ-FeOOH，and the protective corrosion product α-FeOOH accounting for a higher proportion （38%） on the surface of Q450NQR1 compared to Q345NQR2 （36.7%）. The integrity and continuity of the rust layer structure played an important role in resisting external corrosion，and improving the corrosion resistance of weathering steel. During the formation process of the rust layer，the structure of the rust layer was closely related to the distribution of alloy elements. Therefore，EPMA was then employed to observe the distribution of alloying elements at the interface of the rust layers for Q450NQR1 and Q345NQR2. In the rust layer of Q345NQR2，Cu，P，and Cr were found to be enriched to varying degrees，while the Ni was evenly distributed in both the matrix and rust layer，and with a higher content in the matrix. In the rust layer of Q450NQR1，Cu was clearly aggregated on the outer side of the outer rust layer，P showed a weak aggregation on the outer side of the outer rust layer，while Cr and Ni were evenly distributed in the matrix and the rust layer. The interaction of alloying elements Cu，P，Cr，and Ni played a crucial role in the structure of the generated rust layer. In the initial stage of corrosion，the surface of weathering steel would generate an outer rust layer with significant differences in morphology and density，due to the different enrichment states of Cu，P，Cr，and Ni elements. The effect of Cu-Ni on the densification of rust layer was stronger than that of P and Cr elements. If the generated outer rust layer developed into a porous and porous structure，the corrosion process entered the second stage，where the inner rust layer was generated by P-Cr interaction. The lower the density of the outer rust layer，the more intense the second stage of corrosion would be，and the thicker the generated inner rust layer would be. In addition to promoting the formation of a dense rust layer on weathering steel，P could also accelerate the corrosion of the steel substrate. Therefore，in the actual production process，appropriately reducing the content of P and increasing the content of Cu，Ni could effectively reduce the pores in the surface rust layer，thereby improving the corrosion resistance of weathering steel. To sum up，the actual corrosion resistance depended on the composition and structure of the rust layer. The greater the amount of α-FeOOH，the denser the rust layer on the surface of the material，leading to better corrosion resistance. Under the influence of Cu-P-Ni interactions，the outer rust layer of Q345NQR2 was loose and porous，whereas the outer rust layer of Q450NQR1 was continuous and dense. Meanwhile，the refinement effect of NiFe2O4 and FePO4 on the rust layer effectively resisted the invasion of external corrosive agents. Under Cr-P interactions，the outer rust layer was continuously transformed into the inner rust layer，simultaneously，the uniform dissolution of the matrix was accelerated to form a dense inner rust layer. Consequently，the inner rust layer of Q345NQR2 was thicker than that of Q450NQR1. The dense inner rust layer formed by weathering steel played a significant role in resisting further invasion of corrosive agents. Under Cu-P-Cr-Ni interactions，Q450NQR1 exhibited worse electrochemical corrosion performance compared to Q345NQR2，yet displayed better performance in cyclic immersion corrosion than Q345NQR2.
KeyWords AITranslate
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Basic Information:
DOI：10.13373/j.cnki.cjrm.XY23110002
Chinese Library Classification Number:TG142.1
Citation Information:
With the continuous increase of freight volume in heavy railway，the demand for the corrosion resistance of railway freight car body materials has increased. Q450NQR1 and Q345NQR2 are the primary materials used in railway freight car bodies，however，through our investigations，it has been found that the amount of corrosion-induced damage in the actual use of these two materials remains unacceptably high. Therefore，in this paper，the corrosion behavior of Q450NQR1 and Q345NQR2 weathering steels was studied，using electrochemical workstation，cyclic immersion corrosion testing machine，scanning electron microscopy （SEM），X-ray diffraction （XRD），and electron probe microanalysis （EPMA），aiming to explore the reasons for the interaction between alloying elements that affect corrosion resistance and play a crucial role in enhancing the corrosion resistance of weathering steels. The electrochemical corrosion tests of the two weathering steels showed that Q345NQR2 had better electrochemical corrosion performance compared to Q450NQR1，due to the content of Cu，P，Cr and Ni in Q345NQR2 was higher than that in Q450NQR1. The corrosion behavior of Q450NQR1 and Q345NQR2 was also investigated after 72 h of accelerated corrosion in an industrial atmospheric environment，and the results showed that the weight loss rate of Q345NQR2 was 1.264 g·m−2·h−1，higher than that of 1.139 g·m−2·h−1 for Q450NQR1，indicating a poorer corrosion resistance，contrary to the results of electrochemical corrosion. The macroscopic morphology of the sample surface revealed a rougher rust layer for Q345NQR2 compared to Q450NQR1. SEM images of the surface morphology further revealed the presence of corrosion pits on the surface of Q345NQR2，while the rust layer surface of Q450NQR1 was smoother and denser. The corrosion products of both weathering steels were found to be γ-Fe2O3/Fe3O4，α-FeOOH and γ-FeOOH，and the protective corrosion product α-FeOOH accounting for a higher proportion （38%） on the surface of Q450NQR1 compared to Q345NQR2 （36.7%）. The integrity and continuity of the rust layer structure played an important role in resisting external corrosion，and improving the corrosion resistance of weathering steel. During the formation process of the rust layer，the structure of the rust layer was closely related to the distribution of alloy elements. Therefore，EPMA was then employed to observe the distribution of alloying elements at the interface of the rust layers for Q450NQR1 and Q345NQR2. In the rust layer of Q345NQR2，Cu，P，and Cr were found to be enriched to varying degrees，while the Ni was evenly distributed in both the matrix and rust layer，and with a higher content in the matrix. In the rust layer of Q450NQR1，Cu was clearly aggregated on the outer side of the outer rust layer，P showed a weak aggregation on the outer side of the outer rust layer，while Cr and Ni were evenly distributed in the matrix and the rust layer. The interaction of alloying elements Cu，P，Cr，and Ni played a crucial role in the structure of the generated rust layer. In the initial stage of corrosion，the surface of weathering steel would generate an outer rust layer with significant differences in morphology and density，due to the different enrichment states of Cu，P，Cr，and Ni elements. The effect of Cu-Ni on the densification of rust layer was stronger than that of P and Cr elements. If the generated outer rust layer developed into a porous and porous structure，the corrosion process entered the second stage，where the inner rust layer was generated by P-Cr interaction. The lower the density of the outer rust layer，the more intense the second stage of corrosion would be，and the thicker the generated inner rust layer would be. In addition to promoting the formation of a dense rust layer on weathering steel，P could also accelerate the corrosion of the steel substrate. Therefore，in the actual production process，appropriately reducing the content of P and increasing the content of Cu，Ni could effectively reduce the pores in the surface rust layer，thereby improving the corrosion resistance of weathering steel. To sum up，the actual corrosion resistance depended on the composition and structure of the rust layer. The greater the amount of α-FeOOH，the denser the rust layer on the surface of the material，leading to better corrosion resistance. Under the influence of Cu-P-Ni interactions，the outer rust layer of Q345NQR2 was loose and porous，whereas the outer rust layer of Q450NQR1 was continuous and dense. Meanwhile，the refinement effect of NiFe2O4 and FePO4 on the rust layer effectively resisted the invasion of external corrosive agents. Under Cr-P interactions，the outer rust layer was continuously transformed into the inner rust layer，simultaneously，the uniform dissolution of the matrix was accelerated to form a dense inner rust layer. Consequently，the inner rust layer of Q345NQR2 was thicker than that of Q450NQR1. The dense inner rust layer formed by weathering steel played a significant role in resisting further invasion of corrosive agents. Under Cu-P-Cr-Ni interactions，Q450NQR1 exhibited worse electrochemical corrosion performance compared to Q345NQR2，yet displayed better performance in cyclic immersion corrosion than Q345NQR2.
quote
| GB/T 7714-2015 | [1] Hongbo Yang, Jiatong Sun, Xinyi Han, et al. Corrosion Behavior of Weathering Steel for Railway Freight Cars under Interaction of Cu-P-Cr-Ni[J]. Chinese Journal of Rare Metals, 2025, 49(8): 1181-1189. DOI:10.13373/j.cnki.cjrm.XY23110002. |
| MLA | [1] Hongbo Yang, et al., "Corrosion Behavior of Weathering Steel for Railway Freight Cars under Interaction of Cu-P-Cr-Ni." Chinese Journal of Rare Metals, vol. 49, no. 8, 2025, pp. 1181-1189, https://doi.org/10.13373/j.cnki.cjrm.XY23110002. |
| APA | [1] Hongbo Yang, Jiatong Sun, Xinyi Han, Haijie Chen, Jinjing Du, & Weiwei Qi. (2025). Corrosion Behavior of Weathering Steel for Railway Freight Cars under Interaction of Cu-P-Cr-Ni. Chinese Journal of Rare Metals, 49(8), 1181-1189. https://doi.org/10.13373/j.cnki.cjrm.XY23110002 |
| IEEE | [1] Hongbo Yang, Jiatong Sun, Xinyi Han, Haijie Chen, Jinjing Du, and Weiwei Qi, "Corrosion Behavior of Weathering Steel for Railway Freight Cars under Interaction of Cu-P-Cr-Ni," Chinese Journal of Rare Metals, vol. 49, no. 8, pp. 1181-1189, 2025, doi: 10.13373/j.cnki.cjrm.XY23110002. keywords: {alloy elements;rust layer;weathering steel;electrochemistry;cyclic immersion} |