Key points of the pickling process for stainless steel castings of mechanical valves
The pickling process of stainless steel castings is an indispensable part of mechanical valve production. It not only removes the oxide scale and dirt on the surface of the casting but also improves its surface smoothness, extending the service life of the mechanical valve. This article will focus on the key points of the pickling process for stainless steel castings, helping everyone better understand and master this process.
The Necessity of Pickling Process
During the casting process of stainless steel castings, a large amount of oxide scale and impurities are produced. These impurities not only affect the appearance of the casting but also can cause scratches during subsequent mechanical processing, affecting the performance of the mechanical valve. In addition, under high temperatures, these impurities may react with the metallic elements in the casting to generate harmful substances, affecting the service performance of the mechanical valve. Therefore, stainless steel castings need to be pickled before processing to remove the surface oxide scale and impurities.
Two, the process of the pickling process
The pickling process of stainless steel castings mainly includes four steps: immersion, cleaning, rinsing, and drying. First, immerse the stainless steel casting into the pickling solution to allow the pickling solution to penetrate into the gaps of the casting, dissolving the oxidation scale and impurities. Then, remove the casting from the pickling solution, rinse it with clean water to remove the surface pickling solution. Next, immerse the casting into the rinsing solution to rinse off the residual pickling solution and impurities on the surface. Finally, remove the casting from the rinsing solution and dry it with a desiccant or natural air drying to ensure that there is no residual moisture on the surface of the casting.
Three, the key points of the pickling process
Choose the appropriate pickling solution. The composition and concentration of the pickling solution have a direct impact on the pickling effect. Common pickling solutions include hydrochloric acid, sulfuric acid, and nitric acid, among which hydrochloric acid and sulfuric acid are more commonly used. When choosing a pickling solution, it is necessary to consider the material of the casting and the requirements of the pickling effect, as well as environmental factors, choosing a pickling solution that has a smaller impact on the environment.
Control the temperature of the pickling solution. The temperature of the pickling solution affects the solubility and pickling effect of the pickling solution. Generally, the temperature of the pickling solution between 20-40℃ is most suitable.
Adjust the concentration of the pickling solution. The concentration of the pickling solution affects the solubility and pickling effect of the pickling solution. The concentration of the pickling solution is usually adjusted according to the material of the casting and the requirements of the pickling effect.
Control the pickling time. If the pickling time is too short, the solubility and pickling effect of the pickling solution will be affected; if the pickling time is too long, it will damage the surface of the casting. Generally, the pickling time between 30-60 minutes is most suitable.
Avoid using strong acids or bases. Strong acids or bases can cause corrosion on the surface of stainless steel castings, affecting their service life. Therefore, it is necessary to avoid using strong acids or bases during the pickling process.
Avoid using highly corrosive pickling solutions. Highly corrosive pickling solutions can cause corrosion on the surface of stainless steel castings, affecting their service life. Therefore, it is necessary to avoid using highly corrosive pickling solutions during the pickling process.
Avoid using pickling solutions containing harmful substances. Pickling solutions containing harmful substances can cause corrosion on the surface of stainless steel castings, affecting their service life. Therefore, it is necessary to avoid using pickling solutions containing harmful substances during the pickling process.
Four, the treatment after pickling
After the pickling of stainless steel castings, rinsing and drying treatments are required. The rinsing solution is usually clean water or alkaline cleaning solution, used to remove the residual pickling solution and surface impurities. The drying agent is usually anhydrous alcohol or desiccant, used to remove the moisture on the surface of the casting to avoid scratches during subsequent processing.
Summary
The pickling process of stainless steel castings is an indispensable part of the mechanical valve production process. By selecting appropriate pickling solutions, controlling the temperature and concentration of the pickling solution, adjusting the pickling time, and avoiding the use of highly corrosive pickling solutions, the oxidation scale and impurities on the surface of the casting can be effectively removed, thereby extending the service life of the mechanical valve. At the same time, it is also necessary to carry out rinsing and drying treatments to ensure that there is no residual moisture on the surface of the casting.