Factory Price High Quality Steel Coil Hot Rolled Steel Coil

The production process of hot-rolled steel coil is a key link in steel manufacturing. It mainly forms the steel billet into the required plate shape through high-temperature rolling. The following are its core steps:

Raw Material Preparation
The raw material is either a continuous cast slab or bloom, typically 150-300 mm thick.
The slab surface undergoes cleaning (e.g., flame scarfing or mechanical grinding) to remove scale and defects to ensure rolling quality.
Heating
The slab is fed into a walking beam furnace and heated to 1100-1300°C to reach austenitization and enhance ductility.
Heating time and temperature uniformity must be controlled to avoid overheating or underheating.
Roughing
The slab is rolled into intermediate bars 30-50 mm thick in a reversing roughing mill (e.g., a two- or four-high mill).
After each rolling pass, high-pressure water descaling may be performed to remove the surface oxide layer.
Finishing
The intermediate bars enter the finishing mill (typically consisting of six or seven four- or six-high mills), where they are gradually thinned to the target thickness (e.g., 1.2-25 mm) through continuous rolling. Automatic gauge control (AGC) and flatness control systems are used to ensure dimensional accuracy and flatness.
During the rolling process, the rolls require cooling and lubrication to prevent thermal deformation and wear.
Cooling
A laminar cooling system rapidly cools the steel strip from the final rolling temperature (approximately 800°C) to room temperature by controlling the amount of water and the cooling rate (e.g., 30-50°C/second).
The cooling process directly affects the microstructure (e.g., the ferrite to pearlite ratio) and mechanical properties of the coil.
Coiling
The steel strip is wound into coils using pinch rolls and a coiler. The tension is controlled between 100-500 N/mm² to ensure a tight coil shape and no loose coils.
The coiling temperature is typically controlled between 550-700°C to optimize properties.
Post-Processing
Surface treatment: Surface treatment includes pickling to remove oxide scale or coatings such as galvanizing or aluminizing.
Annealing: Improves material ductility (e.g., recrystallization annealing before cold rolling). Flattening: Low-reduction rolling eliminates yielding flat steel and improves surface finish.
Quality Inspection and Packaging: We inspect dimensions, mechanical properties, and surface quality before coiling, bundling, and labeling the product according to customer specifications.