Pioneering the Industry – Lianyuan Steel’s 60Si2Mn Cold-Rolled Wide Steel Coils Make Domestic Debut

Recently, the domestically pioneered product 60Si2Mn cold-rolled wide steel coils developed by Lianyuan Steel were delivered to customers in East China and successfully passed field trials. This milestone achievement marks that Lianyuan Steel has once again opened up a new track in the R&D of medium and high-carbon steel products in China.
60Si2Mn is a high-carbon silicon-manganese spring steel, a classic spring steel grade. Boasting high strength, excellent resilience and fatigue resistance, it is widely used in the manufacturing of key components such as suspension springs, anti-collision bars and deformation arms for the automotive, railway and mechanical engineering industries. For a long time, 60Si2Mn products have mainly been available in the form of narrow strip steel, bars and wires. Only three steel enterprises in China are capable of producing its hot-rolled coils, while the cold-rolled coil variant has long remained a blank in the domestic market.
Developing the hot-rolled and cold-rolled coils of 60Si2Mn has been no easy task, as this material poses immense production challenges. The smelting process demands strict control over the cleanliness of the molten steel, particularly the contents of nitrogen, hydrogen, and oxygen. Both inclusions and gas content in the molten steel can exert a significant impact on the fatigue performance and service life of the springs manufactured from subsequent processing. Owing to its high-carbon and high-silicon properties, the material exhibits extremely high crack sensitivity, making it prone to slab cracks as well as edge cracks during hot and cold rolling. Additionally, precautions must be taken to prevent slab segregation during the continuous casting process.
The R&D team also confronted a host of other challenges. For instance, the hot-rolling process entails an enormous load, marking this steel grade as the one requiring the highest rolling force for millimeter-width rolling at Lianyuan Steel to date. Other issues included difficulties in controlling the sheet shape, crown, and wedge, strip breakage during uncoiling, and a tendency for decarburization.
After prolonged exploration and relentless efforts, the technical team at Lianyuan Steel successfully overcame these technical hurdles and developed the hot-rolled and cold-rolled 60Si2Mn coils. Meanwhile, to meet customer requirements, the technical personnel carried out intensive customer follow-ups and comparative application studies over two months. They analyzed the root causes related to the material's microstructure, readjusted the production processes, and conducted trial production of new batches. By the end of September, they had successfully resolved the problem of inconsistent coloration of the 60Si2Mn cold-rolled wide steel coils after chemical oxidation. Trials by customers in East China confirmed that all quality indicators fully met the required standards.
As a medium and high-carbon strip steel, 60Si2Mn boasts substantial demand in the domestic consumer market. The successful R&D and trial application of its cold-rolled coils represent a milestone in boosting the competitiveness and brand influence of Lianyuan Steel's medium and high-carbon steel products. This achievement not only demonstrates the company's innovative capabilities and technical prowess in the R&D of iron and steel materials but also lays a solid foundation for Lianyuan Steel to promote and expand its market share in the niche market in 2025.