What are the differences between cold rolling, hard rolling, cold forming, and pickling of steel plates, and what are their applications

In the steel plate business, many people often encounter these types of products, and some are confused about the differences: Is pickling considered cold rolling or hot rolling? Is cold forming considered cold rolling or hot rolling? Are hard rolling and cold rolling the same? These are soul-searching questions in the steel trade. Confusing product categories can easily lead to trading risks, disputes, and claims.

First, the definition of steel plate products.

When analyzing product types, it is important to first clarify the definitions of these products. These common terms generally refer to low-carbon steel coils:

- Pickling: Generally refers to a hot-rolled steel coil that has been subjected to a pickling mill to remove surface scale.

- Hard rolling: Generally refers to a hot-rolled steel coil that has been pickled and then thinned in a cold rolling mill, but not annealed.

- Cold rolling: Generally refers to a hard rolling coil that has been fully or partially annealed.

- Cold forming: Generally refers to a hot-rolled pickled thin strip produced via the ESP continuous casting and rolling process.

Second, differences in steel plate production processes.

Pickling, hard-rolling, and cold-rolling products are products of different stages in the traditional production process. Pickling is the product of hot-rolled descaling, while hard-rolling is the product before cold-rolled annealing. However, cold-forming is a new product, produced on ESP lines (which combine continuous casting and hot-rolling processes into a single unit). This process offers low costs and thinner hot-rolled thicknesses, making it a key focus for many domestic steel mills in recent years.

- Pickled coil, unlike hot-rolled coil, has the same base material as hot-rolled coil and is often used in applications requiring higher surface quality than hot-rolled coil. A common grade is SPHC, commonly known in the industry as "pickled C material."

- Hard-rolled coil is not cheap, and its formability and surface quality are poor. Therefore, it is generally used in specific industries with thin gauges and less demanding performance requirements, such as umbrella ribs or factory lockers. A common grade is CDCM-SPCC, commonly known in the industry as "cold-rolled C material."

- Cold-rolled coil has excellent overall performance, but its disadvantage is that it is the most expensive (it requires more processes and has the highest cost). A common grade, SPCC, is commonly known in the industry as "cold-rolled C material."

- Cold-formed coil has significantly better formability than hard-rolled coil, but not as good as cold-rolled coil (primarily affected by heat treatment capacity and post-pickling flat work hardening). Its key advantage is its very low cost, especially in the 1.0-2.0 mm thickness range. It can be used to replace cold-rolled products with less demanding forming requirements (such as rolling and bending).

Additional Information:

1. China has the largest number of ESP production lines globally. Based on the principle that more production leads to faster development, this series of processes (including semi-endless rolling and roll-cast thin plate) may develop into a vast, low-cost product line in a few years. (This includes semi-endless rolling and roll-cast thin plate). The competition for low-carbon steel products may be fierce in the future, but with lower raw material costs, Chinese-made products will be more competitive internationally.

2. Cold-formed coil also serves as a high-quality hot-dip galvanized substrate. Its originally poor mechanical properties can be improved in the annealing process of the hot-dip galvanizing line, enabling the production of hot-dip galvanized products for deep drawing. Furthermore, its cost is significantly lower than that of hot-dip galvanized ESP substrates produced using traditional processes. (In fact, in the Southeast Asian market, hot-dip galvanizing of ESP substrates has become a price-cutting phenomenon.)

3. Regarding ESP products, the industry currently refers to them as "cold forming" and "cold forming," resulting in confusion and a lack of consensus.

4. While neither terminology is rigorous and can be easily confused (there is already considerable confusion in the trade landscape), it's undeniable that whoever develops first wins, and followers, even if they feel uncomfortable, can only follow suit.