kuumavalssaten

Kuumavalssaten, or hot-rolled material, refers to metal products produced by hot rolling, a process in which steel is deformed at temperatures above its recrystallization temperature. The resulting products include hot-rolled coils, sheets, plates, bars, and structural shapes. The term is common in Finnish industry for steels intended for general use where dimensional precision is less critical and cost efficiency is prioritized.

Manufacturing is done from reheated billets or slabs. The material is heated to roughly 900–1100 °C and passed through a series of rolling mills that progressively reduce thickness and form shapes. After rolling, surface oxide scale forms and is typically removed through descaling or pickling. Finishing operations may include tempering, coating, or surface finishing to meet application needs.

Properties: Hot-rolled products have a relatively coarse, fibrous grain structure, yielding improved machinability and formability but looser dimensional tolerances and a rough surface compared with cold-rolled products. Mechanical properties depend on alloy composition and heat treatment; hot-rolled steel generally shows higher toughness and is easier to weld.

Forms and uses: Common forms are hot-rolled coil and sheet, plate, bar, and structural sections such as angles, channels, and I-beams. They serve as raw materials for construction, shipbuilding, automotive components, and heavy equipment. In Europe, hot-rolled products are specified under EN standards (for example structural grades like S235, S355) and correspond to industry codes across regions.

Advantages and limitations: Cost-effective for large volumes; good forming properties; however, surface quality and precision are lower than cold-rolled products unless further processing is applied. Finishing steps like pickling, galvanizing, or coating enhance corrosion resistance where needed.