ES427657A1 - Picking procedure for metal objects, especially applicable to the continuous treatment of materials in the form of string or wire. (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Pickling process for metal objects, especially applicable to the continuous treatment of materials in the form of strip or wire, especially stainless steel, using for this a combination of at least two separate pickling stages, characterized by the fact that the object once annealed, it is exposed to the chemical action of an aqueous solution, which is heated to temperatures above room temperature, but preferably above 30ºc and advantageously between 55ºc and 60ºc, and it contains hf in oscillating proportions between 7% and 25%, although preferably oscillating between 15% and 20%, Or containing hf in the amounts cited above, as well as sulfuric acid in proportions greater than 2%, or containing hf in the amounts mentioned above as well as sodium chloride in up to 10%, but especially in 0.5% a 2.5%, Or containing hf in the amounts cited above, as well as sulfuric acid and sodium chloride in the amounts quoted above, In combination with the fact that the object is exposed in the second stage of the process to the chemical action of an aqueous solution, which is heated to temperatures above room temperature, but in particular above 30ºC and advantageously betweenº and 60º c, and that contains hf and nitric acid. (Machine-translation by Google Translate, not legally binding)