HR, CR, GI, and PPGI represent four different types of steel: hot-rolled steel, cold-rolled steel, galvanized steel, and pre coated galvanized steel.
Hot rolled steel is a type of steel produced by rolling steel billets at high temperatures. During the hot rolling process, the temperature of the steel billet usually exceeds its recrystallization temperature, so the surface of the rolled steel is relatively rough, and there may be some inaccuracies in size and shape. However, hot-rolled steel has high strength and toughness, and is commonly used in applications that require significant mechanical stress.
Cold rolled steel is a type of steel that is rolled after the billet has cooled to room temperature. During the cold rolling process, the surface quality of the steel is significantly improved, and the size and shape are also more precise. The strength and hardness of cold-rolled steel are usually higher than those of hot-rolled steel, but the toughness may be slightly lower. Due to its excellent surface quality and dimensional accuracy, cold-rolled steel is often used to manufacture products that require high precision and high-quality surfaces.
Galvanized steel is a type of steel that is coated with a layer of zinc on the surface of cold-rolled or hot-rolled steel. Galvanized layer can effectively prevent steel from corroding in humid environments, so galvanized steel is often used in fields such as outdoor construction, automobile manufacturing, and home appliance production. The thickness and uniformity of the galvanized layer have a significant impact on the corrosion resistance of steel.
Pre coated galvanized steel is steel that is coated with one or more layers of organic coating on the surface of galvanized steel. This coating not only provides additional anti-corrosion protection, but also endows the steel with rich colors and textures. Pre coated galvanized steel combines the corrosion resistance of galvanized steel with the decorative properties of organic coatings, making it widely used in fields such as building exterior walls, roofs, and interior decoration.