I. Chemical Treatments
Acid Pickling and Passivation: Acid pickling removes surface oxide scale and oil, forming a dense passivation film. This is the default process for industrial pipes, resulting in a matte, silvery-white finish with strong corrosion resistance.
Bright Annealing: Annealing is performed under vacuum or a protective atmosphere, eliminating cold working stress. It produces a high surface finish (Ra≤0.4μm) and is often used for high-purity gases and sanitary pipelines.
Phosphating and Saponification: Forms a water-insoluble phosphate conversion film on the surface. Combined with saponification, it significantly improves lubricity and is suitable for cold drawing, stretching, and other machining processes.
II. Mechanical Treatments
Mechanical Polishing: Using abrasive belts and polishing wheels, rough and fine polishing can achieve mirror or brushed finishes. The surface finish is approximately Ra 0.4-0.8μm, and it is easy to clean and maintain.
Shot Peening/Sandblasting: Sharp-edged abrasive is used to create a rough, matte surface. Spherical shot can simultaneously strengthen the surface and improve the pipe's fatigue resistance.
III. Electrochemical Treatments
Electropolishing: Achieving an ultra-smooth surface (Ra≤0.1-0.2μm) by anolysing microscopic protrusions on the surface, significantly improving corrosion resistance. Widely used in high-cleanliness environments such as medical and pharmaceutical industries.
IV. Coating Treatments
Plastic Coating/Platement: Achieving corrosion resistance, wear resistance, and coloring effects through coating with PE/EP plastics, electroplating with chromium/nickel, etc., suitable for highly corrosive outdoor environments.
