In the steel trading industry, we often find ourselves stuck on complex technical terms. The following terms are frequently used in the field, and gaining a deep understanding of their meanings and distinctions is essential for improving the efficiency and accuracy of our trading and production processes.
Pickling
This refers to hot-rolled pickled coil, a product processed through the traditional hydrochloric acid pickling method. In this process, hot-rolled steel coils are immersed in a hydrochloric acid solution, where a chemical reaction removes the iron oxide scale from the surface, resulting in a cleaner finish. The pickled coils are typically leveled afterward to achieve the desired surface roughness.
It's important to note that pickled products cannot be identified solely by their grade designation, as they share the same steel grades as regular hot-rolled products. To distinguish pickled coils, one must refer to the product category stated in the mill test certificate-for example, pickled SPHC or pickled DD11.
Full Hard
This refers to steel coils that have undergone pickling and are then cold-rolled to reduce thickness, but have not been annealed. These are typically in a work-hardened state.
On some e-commerce platforms, you may come across designations like CDCM-SPCC, which indicate full hard coils produced by a continuous acid-pickling and cold-rolling line.
Cold-Rolled
These are products obtained after the full hard coils undergo complete or partial annealing. Common cold-rolled steel grades include SPCC and DC01. Even partially annealed variants, such as DC01 C590 or SPCC 4B, are classified as cold-rolled products.
ESP (Endless Strip Production)
Also known as cold-forming, this is a process in which hot-rolled pickled thin strip steel is produced using the ESP (endless casting and rolling) technology. These coils are typically pickled and leveled, and are used as substitutes for some cold-rolled structural steels. The commercial-scale production of cold-forming coils was first implemented by Rizhao Steel, with RECC being a well-known grade. Other manufacturers have since introduced similar ESP grades, such as MCFC.
EPS (Eco Pickled Surface)
Also known as acid-free pickling, environmentally friendly pickling, or mechanical pickling. This process removes the oxide scale from the surface of hot-rolled steel coils using mechanical methods (such as abrasive blasting), instead of hydrochloric acid. Because the abrasive particles used are relatively coarse, EPS-treated coils have a higher surface roughness, making them unsuitable for parts that require a high-quality surface finish.