Although cold-formed steel has been used in Chinese railway wagons for over a decade, its application still lags behind countries like Russia and the United States in terms of variety, quantity, and overall maturity. There are several challenges in both the manufacturing process and the loading of cold-formed steel products. First, there is a significant amount of internal stress present in the finished product. During early processing stages—such as unwinding, rolling, rewinding, and flat bending—the material undergoes mechanical deformation, which increases internal stress. Even after cold bending, the material retains high internal stress due to the nature of forced mechanical shaping.
Although a correction process is applied after cold bending, it mainly focuses on adjusting the outer dimensions, with limited effectiveness in reducing internal stress. After storage, noticeable aging deformation occurs, confirming that internal stress remains a major issue. Second, the pre-loading treatment also contributes to deformation. Since the steel is not primed upon delivery, shot blasting is required before loading. While this process removes rust and improves surface passivation, it also releases internal stress, leading to bending or torsional distortion. This effect is especially evident in asymmetrical structures.
Third, although China's weathering steel exhibits good mechanical properties, corrosion resistance, and weldability, its stamping performance is not as favorable as that of ordinary carbon steel. Parts tend to rebound significantly after bending, so careful optimization of process parameters during cold forming is essential to maintain quality. Fourth, the technical standards for new cold-formed steel need urgent improvement. When applying cold-formed steel in railway wagons, specific guidelines should be established for processing, manufacturing, working conditions, and deformation characteristics to support production, usage, and inspection. Currently, no official specifications exist for cold-formed steel in railway wagon inspection standards, which hinders its broader adoption and development.
The use of cold-formed steel in Chinese railway wagons is still in its early stages. Looking at global trends, the application of this material in trucks is expected to grow significantly. Although current challenges remain—such as improving production techniques, finalizing application methods, and establishing industry standards—experts suggest that close collaboration between cold-formed steel manufacturers and truck producers is crucial. By enhancing communication and cooperation, the industry can promote the widespread use of cold-formed steel in rail vehicles, optimize structural design, and elevate the overall performance of railway freight cars to a higher level.
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