On December 19, 2025, Taiyuan Iron and Steel Group Co., Ltd. (TISCO), a subsidiary of Baowu Steel Group, officially implemented its independently developed patent titled "Cold Rolling, Annealing and Pickling Method for Stainless Steel and Precipitation-Hardening Martensitic Stainless Steel SUS630" (Patent No.: CN121160977A).
This patent has achieved low-cost mass production of large-size bars of SUS630 alloy. In terms of core performance, it not only surpasses the traditional mainstream grade 420J2, but also successfully opens up application channels in high-end fields such as aerospace and medical devices. Its export quotation is 20% higher than that of ordinary martensitic stainless steel, marking that China has broken through technical barriers in the field of high-end special stainless steel and stepped into the world's first echelon.
Precipitation-hardening martensitic stainless steel has long dominated high-end markets such as aerospace fasteners and precision medical device components, thanks to its core advantages of high strength, high corrosion resistance and dimensional stability. Among them, SUS630 (corresponding to the domestic grade 0Cr17Ni4Cu4Nb, also known as 17-4PH) is a representative grade in this category. It requires precise composition ratio and complex heat treatment process to achieve performance balance.
Previously, this technology has long been monopolized by a few international giants. Domestic production capacity mostly relied on imports or small-batch trial production, and high costs have become a key bottleneck restricting the development of downstream high-end equipment industries.
The core breakthrough of the patent technology implemented by TISCO lies in the innovative cold rolling, annealing and pickling process. Through the full-process optimization of "sectional preheating - precise solution treatment - gradient pickling", the preheating temperature of SUS630 steel strip is controlled at 400-800℃, the solution annealing temperature is stabilized at 980-1060℃, and the holding time is accurately matched according to materials of different thicknesses.
The final large-size bars produced have a hardness of HRC28-35, a yield strength of 700-1100 MPa and a tensile strength of 1000-1300 MPa, with comprehensive mechanical properties reaching the international advanced level. More importantly, process optimization has increased the yield rate of SUS630 production to over 91% and reduced energy consumption per ton of steel by 18%, completely changing the predicament of "high cost and low production capacity" in the traditional production process.
Compared with 420J2 (corresponding to the domestic grade 4Cr13), the current mainstream grade in the market, TISCO's SUS630 shows significant performance advantages.
- Corrosion Resistance Upgrade: As a high-carbon martensitic stainless steel, 420J2 is prone to rust when exposed to water or acidic environments for a long time. In contrast, by adding alloying elements such as nickel, copper and niobium, TISCO's SUS630 has improved corrosion resistance by more than 40% and performs stably in neutral and weak acid environments.
- Application Scenario Expansion: SUS630 has excellent biocompatibility and can be used in the manufacture of small implants such as orthopedic bone plates and screws. Its good weldability also solves the pain point of 420J2 in processing complex components, making it perfectly suitable for high-end fields such as medical devices and aerospace.
In terms of application scenario expansion, TISCO's SUS630 patented product has achieved breakthroughs in multiple fields. In addition to aerospace and medical devices, relying on its excellent thermal stability and dimensional accuracy, the product has successfully entered the core link of the high-end electronic circuit industry. In the thermal lamination process of printed circuit boards (PCB), it can replace imported materials to ensure the stability of circuit carriers, helping the localization upgrading of high-tech industries such as 5G, autonomous driving and smart medical care.
According to TISCO's technical team, a number of domestic aerospace manufacturers, medical device manufacturers and electronic component leaders have completed product certification, and the first batch of orders has been delivered. Mass supply will significantly reduce the material procurement costs of downstream industries.
From the perspective of the global market pattern, the implementation of TISCO's SUS630 patent is of milestone significance. According to the 2025 Global Martensitic Stainless Steel Market Report released by YH Research, China has become the world's largest consumer of martensitic stainless steel, accounting for more than 30% of the global market share. Among them, the demand for high-end products is growing at an annual rate of over 8%, but there has been a long-term gap in domestic supply.
Through technological innovation, TISCO has achieved low-cost mass production, which not only fills the domestic gap, but also breaks the international technological monopoly, making China one of the few countries in the world with the capacity for large-scale production of SUS630 large-size bars.
In the export market, TISCO's SUS630 has formed dual competitiveness in terms of price and performance. Its export quotation is 20% higher than that of ordinary martensitic stainless steel, but 10%-15% lower than that of imported similar products. At present, it has obtained EU CE certification and international aerospace material standard certification, and is actively expanding high-end markets such as North America and Southeast Asia. Industry insiders analyze that with the mass export of the product, it will reshape the global competitive pattern of high-end martensitic stainless steel, promoting the transformation of China's stainless steel exports from being dominated by low-end products with "increasing volume but falling prices" to high-end products with "high quality and favorable prices".
