World Record: Ultra-thin Hot Rolled Strip Produced in China by Primetals Technologies

- In a first, casting-rolling line achieves thickness of just 0.6 mm
- Thin hot strip now covers more than 80% of cold-rolled thicknesses
- Extended product range, especially for cold strip substitutes

Creating a new benchmark, an Arvedi ESP (Endless Strip Production) line installed in a plant belonging to the Chinese steel producer Rizhao Steel Group and supplied by Primetals Technologies produced ultra-thin hot strip just 0.6 mm thick for the first time in October 2018.

The hot strip - the thinnest that has been produced after the line entered service in April last year - can cover more than 80% of regular commercial cold-rolled thicknesses and widens Rizhao's range of products, especially for cold strip substitutes.

The latest production record was achieved during a test in which eight coils were produced with strip thicknesses of less than 0.8 mm after 10 years of incessant development of the endless concept. This production sequence involved progressively reducing the strip thickness to 0.75, 0.7 and finally 0.6 mm before continuing the sequence with increasing thicknesses.

ESP mills are guaranteed to produce strip thicknesses of 0.8 mm, which are used industrially and traded for direct applications. Whereas a strip thickness of 0.8 mm covers around 50% of cold-rolled thicknesses, a strip thickness of 0.6 mm can cover more than 80% of cold-rolled thicknesses. Conventional hot strip production has a lower thickness limit of 1.8 mm, or 1.2 mm for special processes.

Achieving this unprecedented level of thinness is due to the extremely high stability of the ESP process accompanied by constant speeds and temperatures. The process is controlled by ultra-thin rolling technology based on control concepts applied in cold rolling technology.

The Arvedi ESP system produces hot strip directly from liquid steel in a linked casting and rolling mill. Mills of this type have energy consumption and associated costs up to 45% lower than conventional mills with separate casting and rolling processes. They also have substantially reduced CO2 emissions.

The dimensions of these mills, with a length of only 155 m, are considerably more compact than conventional casting and rolling mills with the casting and rolling line controlled by standardized, integrated basic (level 1) and process (level 2) automation, which ensures finely coordinated interaction of the casting and rolling processes.

Rizhao Steel is a company in the Rizhao Steel Holding Group with headquarters 30 km from Rizhao Harbour in the south of Shandong Province. The company has an annual production capacity of around 15 MnT of crude steel with a product portfolio covering hot-rolled coils, wire, rods and small I-beams, which are primarily sold to Chinese customers.

Arvedi ESP mill no. 4 is, supplied by Primetals Technologies, is designed for an annual production of 1.7 MnT of high-quality, ultra-thin hot strip, in widths ranging from 900 to 1,300 mm. The maximum casting speed is 7 m per minute, and the coil weight is 28 metric tonnes.

Headquartered in London, Primetals Technologies is a leading engineering, plant-building and lifecycle services partner for the metals industry. The company offers a complete technology, product and service portfolio that includes integrated electrics, automation and environmental solutions.