The large-diameter iron-nickel-based alloy tube technology represents a self-developed specialized project in China, with no existing domestic or international experience for reference. Building on successful trials of small-diameter alloy tubes, Daye Special Steel conducted comprehensive verification across multiple processes including tooling preparation, billet heating procedures, and deformation distribution during rolling, complemented by production process simulations. The company pioneered several technological breakthroughs: adopting Φ750mm tube blanks, optimizing alloy materials, implementing double vacuum melting, and employing multiple upsetting-drawing forging processes. These innovations resolved critical production challenges, ensuring successful single-pass rolling of specific large-diameter iron-nickel-based alloy tubes that fully meet technical requirements for process parameters, internal microstructure properties, and dimensional accuracy.
This new generation of ultra-supercritical large-diameter alloy tubes, produced through hot-rolling technology for the first time, offers significant cost advantages over conventional hot extrusion methods. This technological advancement is expected to substantially reduce power plant construction costs and holds profound implications for promoting energy conservation and emission reduction in thermal power generation.