Metal pickling is a process that is used to treat metal surfaces. It serves to remove impurities from the metal, including stains, rust, scale, and inorganic contaminants. The solution that is used for this process is called pickle liquor, and it contains acids that remove the impurities from the metal. Metal pickling is often used to clean steel. Typically, hot rolled steel is treated with a metal pickling process before the steel moves on to the cold forming stage.
Metal working processes often require the use of extremely high temperatures, which can leave a layer of oxidation on the surface of the metal and creates a stain or scale. The scale that tends to form on steel is made up of iron oxide crystals. Metal pickling is used to remove this scale. The steel is dipped into a vat of the pickle liquor, and the acid dissolves the stain.
Hydrochloric acid is usually used for metal pickling. In the past, sulfuric acid was used, but hydrochloric acid works faster than sulfuric acid and reduces the amount of base metal that is lost. Hydrochloric or sulfuric acid is used to clean metals that have an alloy content of 6% or less. If the alloy content is greater than 6%, then a two-part pickling process must be used. This two-part process involves the use of additional acids, such as phosphoric, nitric, and hydrofluoric acid. An inhibitor, such as citric acid, must also be added to the pickling solution to prevent the steel itself from dissolving or becoming pitted.
After pickling, the item is washed. Then the item is often treated with a coating of water soluble oil. The coating forms a barrier to prevent moisture in the air from affecting the metal. The oil coating prevents rust and extends the life of the part. Before the metal can be painted, plated, or fabricated, the oil coating must be removed.
Springco Metal Coating provides metal pickling services as part of their zinc phosphating system. Hydrochloric acid is used to clean away impurities such as inorganic contaminants, rust, smut, and laser oxide. The parts are then treated with a water soluble oil, which protects the part through additional processes and extends its life.
For more information on metal pickling services, get in touch with Springco Metal Coating. We provide a variety of metal coating services, including powder coating, electroplating, and much more. We have been a leader in metal coating services for more than 25 years, so contact Springco Metal Coating to learn more about the options and our services today.
Springco Metal Coating can coat parts with a profile of 72” x 24” x 36” and up to 1,000#s
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