The production of heavy rail is a complex and delicate process involving multiple key links, each of which has a significant impact on the quality of the final product.
Raw material preparation is the first step in heavy rail production. High quality raw materials such as iron ore and scrap steel are rigorously screened before entering the production process. Among them, for the production of heavy rail steel, the control of impurity content in raw materials is extremely strict, especially harmful elements such as sulfur and phosphorus, as they can seriously affect the performance of the steel. For example, sulfur can cause thermal brittleness in steel, reducing its strength and toughness; Phosphorus can increase the cold brittleness of steel, affecting its performance in low-temperature environments.
The smelting process is the core of heavy rail production. Generally, converter or electric furnace is used for steelmaking, and the raw materials are refined into molten steel that meets the chemical composition requirements of heavy rail steel by precisely controlling the temperature, chemical reactions, and other conditions inside the furnace. As mentioned earlier, heavy rail steel has strict standards for the content of elements such as carbon, manganese, and silicon, and the chemical composition needs to be precisely adjusted by adding corresponding alloying elements during the smelting process. Afterwards, refining treatment will be carried out, such as using equipment such as LF (ladle refining furnace) and RH (vacuum circulation degassing device), to further remove impurities from the molten steel, reduce gas content, and improve the purity of the molten steel.
Continuous casting or die casting is the process of converting molten steel into solid steel billets. The continuous casting process is widely used in modern heavy rail production due to its advantages of high efficiency and stable quality. During the continuous casting process, molten steel is injected into the crystallizer through an intermediate ladle and rapidly cooled and solidified inside the crystallizer to form a cast billet. To ensure the quality of the cast billet, it is necessary to precisely control parameters such as the casting temperature, casting speed, and cooling intensity of the molten steel. For some heavy rails with special requirements, the casting method may also be used to cast molten steel into specific molds for shaping.
Rolling is a key process for processing steel billets into heavy rails. The heated steel billet is fed into the rolling mill and gradually rolled into heavy rails that meet the size and shape requirements through multiple passes of rolling. During the rolling process, it is necessary to strictly control parameters such as rolling force, rolling temperature, and rolling speed to ensure the dimensional accuracy, surface quality, and internal structural properties of the heavy rail. For example, by controlling the rolling temperature reasonably, the grain size inside the heavy rail can be refined, thereby improving the strength and toughness of the heavy rail.
Finally, there is the finishing process, which includes steps such as straightening, non-destructive testing, and cutting. Straightening is to eliminate the bending deformation of heavy rails during the rolling process, so as to meet the standard straightness requirements. Ultrasonic testing is the use of ultrasonic, electromagnetic and other testing techniques to detect whether there are cracks, pores and other defects inside and on the surface of heavy rails, ensuring the quality, safety and reliability of heavy rails. The cutting process divides large-sized heavy rails into sections according to standard lengths or customer requirements for transportation and use. The entire heavy rail production process, through strict control and collaborative cooperation in each link, produces high-quality heavy rail products that meet the needs of railway construction and operation.