Acid pickling treatment process of stainless steel

Abstract

The invention discloses an acid pickling treatment process of stainless steel. The acid pickling treatment process comprises the following steps: (1) preparing materials according to weight percentage: 20-22% of nitric acid, 5-7% of hydrofluoric acid and the balance of water; (2) preparing a solution, namely, uniformly mixing and stirring the prepared materials according to the mass proportion; (3) loosening an oxidation film: soaking stainless steel to be treated in sulfuric acid with the volume concentration of 10-15% at the temperature of 800 DEG C for 20-25 minutes; (4) removing the oxidation film: soaking the stainless steel to be treated in the prepared solution, performing normal temperature treatment for 10-15 minutes and then taking out, thoroughly cleaning the surface of the stainless steel with water, cleaning with an alkaline liquor for neutralizing, and finally airing after thorough cleaning. According to the acid pickling treatment process of stainless steel provided by the invention, through the strict control over technological parameters, the oxide scale removing speed and efficiency are high, the corrosion to the matrix is little, the corrosion inhibition rate is high, and no acid mist is produced during the cleaning operation process.

Description

technical field [0001] The invention relates to a stainless steel surface treatment process, in particular to a stainless steel pickling treatment process. Background technique [0002] The stainless steel pickling passivation process is to remove a layer of oxide scale and other metal compounds on the surface of stainless steel after pickling, rolling or other processing processes. The surface chromium is precipitated to form a layer of chromium oxide, which has a strong passivation ability and can prevent it from reacting with other substances, so as to achieve the purpose of stainless steel. The corrosion resistance of stainless steel is mainly due to the fact that the surface is covered with a very thin and dense passivation film, which is isolated from the corrosive medium and is the basic barrier for stainless steel protection. Stainless steel workpieces will form an oxide film when placed in the air, but the protection of this film is not perfect. Usually, it needs ...

AI Technical Summary

Problems solved by technology

In the prior art, when stainless steel pipe fittings are pickled and passivated, the process is complicated and there are many steps. The ratio of pickling and passivation solution is often determined by each manufacturer according to its own materials and production experience. The determined ratio is different. Stable, the use effect is not ideal, there are shortcomings such as incomplete removal of oxides on the surface of the pipe fittings after pickling, insufficient passivation film formation, poor finish, etc.