In the wave of the stainless steel industry moving towards high-end, intelligent, and green development, hot-rolled stainless steel coil production lines, as a core manufacturing link, are profoundly reshaping the industry's productivity landscape through technological iteration and equipment upgrades. In recent years, leading domestic steel companies such as Taiyuan Iron & Steel, Baosteel Desheng, and Tsingshan Special Steel have launched production line renovation projects. Through systematic innovation in four dimensions—process reconstruction, equipment upgrading, intelligent empowerment, and green and low-carbon development—they have broken through the efficiency bottlenecks and quality boundaries of traditional production lines, achieving a comprehensive leap in capacity, quality, cost, and efficiency, providing stronger material support for high-end equipment, new energy, and automobile manufacturing.

Process Iteration: From Segmented Discrete to Continuous and Efficient, Reconstructing Production Logic

Traditional hot-rolling production lines adopt a segmented process of "heating—rolling—cooling—offline annealing—pickling." The slab is repeatedly cooled and reheated between processes, resulting in high energy consumption, long cycles, and increased metal loss and shape defects. The core of this upgrade is the innovation of a full-process hot continuous process, completely breaking down the barriers between stages. Breakthrough in "Three-in-One Hot Rolling" Technology: Represented by Qingtuo Special Steel, this is the world's first integrated "hot rolling, hot charging, and hot annealing" model. After hot rolling, the slab is directly charged into the annealing furnace at a high temperature without cooling, achieving a closed-loop hot process from smelting to finished product. Compared to traditional processes, heat energy consumption is reduced by approximately 30%, the production cycle is shortened by more than 40%, and intermediate transfer and secondary heating costs are completely eliminated.

Optimization of Ultra-Thin Wide-Width Rolling Technology: New-generation hot continuous rolling lines such as Taiyuan Iron & Steel's 1780mm and Baosteel Desheng's 1730mm have optimized rolling paths and pass allocation for 300 and 400 series stainless steel. Through high-precision temperature field control and dynamic roll gap adjustment, they have broken through extreme specifications, stably producing ultra-thin wide-width coils with thicknesses of 1.8mm-6mm and widths up to 2250mm, with thickness tolerance precisely controlled within ±0.05mm, filling the gap in high-end thin-gauge hot-rolled coils in China. Precision Cooling and Heat Treatment:Upgrading laminar flow cooling and water curtain cooling systems, and customizing cooling curves for different steel grades such as ferritic, austenitic, and duplex steels. For example, Baosteel Desheng's production line optimized the cooling path for 430 and 441 ferritic stainless steel, increasing the product's yield strength by more than 10%, while reducing the difficulty of subsequent annealing and decreasing heat treatment energy consumption and time.

Equipment Upgrade:From General-Purpose and Inefficient to Precision and Intelligent, Strengthening the Hardware Foundation

The core of production line iteration is the upgrading of core equipment. By eliminating outdated rolling mills, heating furnaces, and coiling equipment, and introducing a new generation of high-power, high-precision, and highly automated equipment, the rolling stability and extreme processing capabilities are comprehensively improved.

Rolling Mill Equipment Upgrade:Taiyuan Iron & Steel (TISCO) replaced its long-serving 1549mm hot strip rolling line with a newly built 1780mm conventional hot strip rolling line, with a designed annual capacity of 4.8 million tons, including 1.35 million tons of stainless steel coils. The finishing mill adopts a new generation of high-rigidity stands, with a maximum rolling force of 90,000 kN and a rolling speed increased to 8.0 m/s. The sheet shape control capability is improved by 50% compared to the old line.

Qingtuo Special Steel is equipped with China's first 3500mm stainless steel hot-rolling mill. The single-slab mill stand weighs 360 tons and is suitable for rolling ultra-wide and thick stainless steel billets, enabling single-sheet rolling of 3-meter wide, 6mm thick plates.

The coiling equipment has been completely upgraded to a fully hydraulic coiler, with a maximum coiling speed of 22 m/s. It is suitable for high-speed, stable coiling of high-strength stainless steel, completely solving quality defects such as deviation and "butterfly edges" found in traditional coilers.

Heating and auxiliary equipment have been innovated. The traditional pusher-type heating furnace has been replaced with a new high-efficiency walking beam heating furnace, equipped with a pulse combustion and air-fuel ratio automatic control system. Heating efficiency is improved by 25%, and the slab temperature difference is controlled within ±10℃, avoiding rolling defects caused by uneven heating. The newly added integrated online descaling, online finishing, and surface inspection equipment simultaneously completes oxide scale removal, plate shape correction, and surface defect detection during the rolling process, achieving a first-pass surface quality rate of over 95%, eliminating the need for subsequent offline finishing and reducing secondary processing losses.