Recently, the largest diameter iron-nickel alloy pipe in China, trial-produced by Huangshi Daye Special Steel and rolled by Zhejiang Taifu Seamless Steel Pipe Co., Ltd. (hereinafter referred to as “Zhejiang Steel Pipe”), was successfully rolled. This specification is the largest diameter iron-nickel alloy pipe in China used in high-parameter environments such as 650℃-level ultra-supercritical power plants, filling a domestic gap and providing strong support for the high-end equipment manufacturing of my country’s power industry.
Large-diameter iron-nickel alloy pipes for 650℃-level ultra-supercritical power plants have been included in the National Key Special Research and Development Program. Due to its high alloy content, this material has high deformation resistance and a narrow hot deformation process window, making it extremely difficult to form. To overcome key core technologies, Daye Special Steel’s R&D personnel spent six years experimenting, collecting data, and conducting trials, successfully trial-producing multiple batches of small and medium-diameter alloy pipes.
Large-diameter iron-nickel alloy pipe technology is a special research project independently developed in my country, with no relevant experience to draw upon domestically or internationally. Daye Special Steel, through accumulating successful experience in the trial production of small-diameter alloy pipes, has continuously optimized its production processes. In collaboration with Zhejiang Steel Pipe R&D personnel, it has repeatedly demonstrated and refined processes in tooling preparation, billet heating technology, and rolling deformation allocation, simulating the production process using a sand table. It pioneered the use of technologies such as φ750mm billets, optimized alloy raw materials, double-vacuum smelting, and multiple upsetting and forging processes to overcome bottlenecks in the production process. During production, R&D, technical, production, and equipment personnel worked alongside the company throughout the process, collaborating across provinces to develop new products. This ensured the successful one-time rolling of a certain grade of large-diameter iron-nickel-based alloy pipe, with process parameters, internal microstructure, and dimensional accuracy all meeting process requirements.
“The new generation of ultra-supercritical large-diameter alloy pipes produced using hot rolling technology for the first time has lower costs than hot extrusion pipe production, which will reduce power plant construction costs and has profound significance for promoting energy conservation and emission reduction in thermal power,” said Liu Wenxue, Party Secretary and General Manager of Daye Special Steel. He added that in recent years, Daye Special Steel has focused on high-quality development, introduced advanced equipment, encouraged innovative R&D, actively served key national projects, and cultivated and developed new productive forces, contributing to the continuous advancement of Chinese manufacturing towards high-end standards.
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Post time: Jan-16-2026