Pickling: that is, "hot-rolled pickled coil", mainly refers to hot-rolled steel coils treated with traditional hydrochloric acid pickling process. The process involves immersing the hot-rolled steel coil in a hydrochloric acid solution to remove the surface oxide scale through chemical reaction to obtain a clean surface. The pickled product is usually flattened to adjust to a suitable surface roughness. It should be noted that pickled products cannot be directly identified by the grade alone, because they share the same grade as hot-rolled products. To distinguish pickled products, you need to rely on the category description in the warranty, such as: pickled SPHC, pickled DD11, etc.
Hard rolled: usually refers to the hot-rolled steel coil after pickling, and then rolled and thinned by cold rolling mill, but not annealed. On e-commerce platforms, you may see logos such as CDCM-SPCC, which represents hard rolled coils produced by acid continuous rolling units.
Cold rolled: products that are fully or partially annealed after hard rolled coils. In trade, common cold rolled grades include SPCC, DC01, etc. Even partially incompletely annealed products, such as DC01 C590 or SPCC 4B, are classified as cold rolled.
ESP: Cold Forming refers to hot-rolled pickled thin strip produced by the ESP (continuous casting and rolling) process. Cold-formed coils on the market are usually pickled and leveled to replace some cold-rolled structural steel. Commercial mass production of cold forming was first achieved by Rizhao Steel, whose brand RECC is well known, and other manufacturers' continuous casting and rolling process brands such as MCFC are now also common.
EPS: Acid-free pickling, also known as environmental pickling or mechanical pickling. This process does not use hydrochloric acid solution, but uses mechanical methods (such as sandblasting) to remove the iron oxide scale on the surface of hot-rolled steel coils. Because the sand used should not be too fine, the surface roughness of EPS pickled plates is relatively high, so it is not suitable for parts with high surface quality requirements.