Recently, the domestically first product, a 60Si2Mn cold-rolled wide-width coil developed by Ly Steel was successfully tested after being sent to users in East China. This milestone achievement means that Ly Steel has once again opened up a "new track" in the industry in the research and development of domestic medium and high-carbon steel products.
60Si2Mn is a high-carbon silicon-manganese spring steel, a classic spring steel grade. Because of its high strength, good resilience, and fatigue resistance, it is widely used in key components such as suspension springs, anti-collision strips, and deformation arms in many industries such as automobiles, railways, and mechanical engineering. For a long time, the product form of 60Si2Mn has mostly been narrow strip steel and bar and wire products. Only three domestic steel companies can produce hot-rolled coils, and cold-rolled coil products have always been blank in China.
The research and development of 60Si2Mn hot-rolled and cold-rolled coils is not an easy task. The material is extremely difficult to produce, and the smelting process requires strict control of the cleanliness of the molten steel, such as the content of N, H, and O. The inclusions and gas content in the molten steel will affect the fatigue performance and service life of the springs processed later. Due to the characteristics of high carbon and high silicon, the crack sensitivity is extremely high, and ingot cracks, hot-rolled, and cold-rolled edge cracks are very easy to occur. In the continuous casting process, it is also necessary to prevent ingot segregation problems. During the research and development process, the technical team also faced many challenges, such as the extremely high hot rolling load. It is currently the type of steel with the largest millimeter-level rolling force in Ly Steel. There are also many problems such as difficulty in controlling plate shape, convexity and wedge shape, unwinding and breaking of the strip, and easy decarburization.
After a long period of exploration and hard work, the technical team of Ly Steel overcame these technical difficulties and successfully developed 60Si2Mn hot-rolled and cold-rolled coils. At the same time, in order to meet customer needs, Ly Steel technicians have been intensively tracking and comparing users for two months, analyzing the reasons such as the material structure, re-adjusting the process, and conducting new batches of trial production. At the end of September, the problem of different colors of Ly Steel 60Si2Mn cold-rolled wide coils after chemical oxidation was successfully solved. After trial use by users in East China, all quality indicators meet the requirements.
60Si2Mn medium-to-high carbon strip steel is a product with relatively large demand in the current domestic consumer market. The successful research and development and trial use of this cold-rolled coil is of nodal significance for enhancing the competitiveness and brand influence of Ly Steel's medium-to-high carbon products. It demonstrates Ly Steel's innovative capabilities and technical level in the field of steel material research and development, and lays a good foundation for Ly Steel's promotion and expansion in the market segment in 2025.