Hot rolled pickling

Hot-Rolled Steel Pickled

Hot-rolled steel pickling is a processing technology used in the production of hot-rolled steel. The process allows for the removal of certain surface contaminants such as mill scale, paint and dirt that form on the surface of the steel in the manufacturing process. In addition to helping form a clean surface the pickling process results in better conditions for subsequent coating processes.

In hot-rolled steel pickling, steel is brought up to the desired temperature in order for the process to take effect. This temperature depends on the type of steel and usually ranges from 800-1050°C (1472-1922°F). When the steel has been heated to the correct temperature, it is then transferred to the pickling tank or vat to start the pickling process.

The pickling vat consists of an acid bath that can be controlled and adjusted to the desired temperature and concentration levels necessary to properly pickle the steel. For example, for boiler tubes, it may require a sulfuric acid bath of 98-99% concentration at temperatures up to 40°C (104°F).

Once the steel is immersed in the hot acid solution, reacting to the surface contaminants and rust, hydrogen ions are released that react with the oxides on the steel surface. As this occurs, the steel will turn a gray-black color due to the iron oxide that is being released. After a few seconds, the steel will then turn a pink-yellow color. Depending on the steel type and surface contaminants, the pickling process can take anywhere from 5-20 minutes.

Once the steel has gone through the pickling process, it can then be neutralized. This is done by rinsing the steel in a hot bath of water and baking soda. The baking soda helps to neutralize the acid solution and prevent corrosion.

Once the neutralization process is complete, the steel is then automatically or manually rinsed in cold water to remove any trace of contaminants and to cool the steel. After the final rinse, the steel is then dried and the pickling process is complete.

The hot-rolled steel pickling process is an integral part of the steel production process as it helps to create a better surface finish for subsequent coating processes. The process can be automated, allowing for higher levels of production and improved operational efficiency.

Hot-rolled acid pickling is a steel surface treatment process based on acid solution. Generally, the acidic solution used is dilute sulfuric acid, and the concentration and temperature of the acid solution are related to the type of steel being treated. The main purpose of the hot-rolled acid pickling process is to remove the scale on the surface of the hot-rolled steel, so that the surface of the steel material can obtain a certain degree of cleanliness, and improve its rust and corrosion resistance.

Hot-rolled acid pickling process is generally divided into the following three steps.

Firstly, the hot-rolled steel is placed in the acid solution, and the steel material is soaked in the acid solution for a certain period of time to make the acid solution and the steel material interaction, so that the oxide film on the surface of the steel material is removed.

Secondly, the steel material is removed from the acid solution and washed with plenty of water until it is clean and there is no residue.

Finally, further corrosion protection is applied. A layer of corrosion-resistant paint is applied to the pickled steel material surface to further protect the steel material from corrosion.

Hot-rolled acid pickling is beneficial to the processing properties of the steel material and plays a great role in improving the surface finish of the steel material. After hot-rolled acid pickling, the surface finish of the steel material is improved, and the rust and corrosion resistance of the steel material is also improved.