Smelting and Materials Technology Innovation

Ultra-Low Carbon Stainless Steel Smelting Technology

By introducing advanced refining processes (such as RH vacuum degassing and AOD argon oxygen decarburization), the carbon content in stainless steel is effectively reduced, improving the material's corrosion resistance and weldability. For example, at a Shanghai stainless steel plant, this technology not only reduced energy consumption and production costs, but also significantly improved the company's economic benefits.

Alloy Composition Optimization

By adding trace elements such as vanadium and niobium, the grain boundary stability and hydrogen embrittlement resistance of the pipe material are enhanced to meet the requirements of high-pressure and high-temperature environments. For example, the composition of pipes used in hydrocracking units in the petrochemical industry has been adjusted to withstand temperatures exceeding 450°C and hydrogen sulfide corrosion.

Manufacturing Process Innovation and Upgrade

1. Improving the Efficiency and Precision of the Hot Extrusion Process

Equipment and Die Improvements: Utilizing vertical hydraulic piercing equipment, the wall thickness tolerance of the steel pipe is controlled within 5%-7%, improving product dimensional accuracy. Over 60% of seamless stainless steel pipe is produced globally through hot extrusion, making it particularly suitable for small-batch, multi-specification pipe production. Combining raw materials and processes: Continuously cast billets are used as raw material to ensure consistent quality while also supporting the production of special-shaped tubes (such as square and oval tubes). A domestic factory uses solid billets for piercing and extrusion on a vertical hydraulic piercing machine, significantly improving efficiency.

2. Breakthroughs in Cold Working and Warm Rolling Technologies

A combined cold rolling and cold drawing process: Cold rolling controls tube wall thickness, while cold drawing adjusts outer diameter specifications to meet the precision requirements of various industries. A company in Jiangsu Province uses this process to achieve efficient production of small-sized tubes.

Warm rolling technology: Heating the cold-rolled raw material to 150-400°C reduces rolling pressure and increases the deformation per roll. For example, for 0Cr18Ni9Ti stainless steel tubes, the total deformation can reach 98% after 23 warm rolling passes, eliminating the need for intermediate annealing and significantly improving production efficiency. 3. Composite Pipe Manufacturing Technology

Bimetallic composite pipe technology: Through explosive lamination or hot-rolled lamination, a corrosion-resistant inner layer (such as high-chromium cast iron or titanium alloy) is combined with a high-strength outer layer (carbon steel), reducing the cost of pure precious metal pipes. For example, coal chemical gasifier slag pipes utilize bimetallic composite pipes. The inner layer, made of high-chromium cast iron with an HRC of ≥58, ensures wear and corrosion resistance, while the outer layer of carbon steel provides structural strength.