Steel Plates Steel Foundations
Plates are heavy-gauge flat products from the hot rolling process.
The plate rolling process begins with a slab or bloom exiting the reheat furnace at a rolling temperature hot enough to achieve the desired final properties. Due to the extreme amount of reduction done during this process, the material must be heated above its recrystallization temperature. After reheating, the material is descaled, which is where the iron oxide surface scale is removed with high-pressure water to ensure a clean surface.
The hot slab or bloom then enters the roughing mill to begin reducing the slab’s thickness. As the slab is reduced in thickness, its length increases, and its as-casted microstructure breaks down. To limit the length required for the process, some plate mills use one rolling mill stand to reduce the plate to its final thickness. Other plate mills use multiple sets of rolling mill stands to achieve the required thickness. A Steckel mill maintains the material’s temperature by installing heated coil boxes on either side of the rolling mill stand. The plate material will coil into one box as it is rolled, then uncoil from the first box, be rolled further, and then recoiled into the opposing box. This reversing process continues until the final thickness is achieved. Next, the plate will be cooled via water sprays, which regulate and develop the steel’s microstructure, grain size, and properties. A shear will then crop the plate into the appropriate lengths before it exits the process to a cooling bed.
The rolled plate thickness ranges from approximately 0.25–17.5 inches (6–440 mm) in widths of approximately 40–220 inches (1,000–5,500 mm). If the plate has been quenched and tempered, the plate will be harder and stronger, and can be used in places such as military armor or hard rock mining equipment. Final plate products can be sold as either coils, if the thickness is one inch (25 mm) or less, or discrete plate, which can be up to 17.5 inches (440 mm) thick and up to 220 inches (5,500 mm) wide.
Plates are produced in a variety of steel grades and properties for a wide variety of applications, such as the manufacturing of welded girders, flooring, storage tanks, machinery parts, barges, and ships. Specialized steel plates such as high-strength, low-alloy, heat treated, or alloy plate, can have superior strength and performance characteristics for applications in construction, mining and logging equipment, pressure vessels, oil and gas transmission lines, and the fabrication of bridges and buildings. Checkered steel plate, better known as diamond plate, is produced using patterned rolls that impress the pattern onto the surface of the plate during hot rolling. It is used for a better grip on flooring applications or simply for aesthetic appeal.