High carbon steel sheet is widely used due to its high strength and wear resistance, but in actual use, its surface is easily affected by oxidation, corrosion and other problems that affect its performance and life, so surface treatment is particularly important.
Painting is a common and practical surface treatment method. By spraying paint, powder coating and other materials, a dense protective film can be formed on the surface of the sheet to isolate the contact between air and moisture and the sheet, thereby effectively preventing rust. Different types of coatings have different properties, such as epoxy resin paint has strong chemical corrosion resistance, and polyurethane paint has good wear resistance and weather resistance. Before painting, the surface of the sheet needs to be cleaned and polished to ensure that the coating can be firmly attached, otherwise it is easy to peel off and affect the protective effect.
Hot-dip galvanizing can significantly improve the corrosion resistance of high carbon steel sheet. The sheet is immersed in molten zinc liquid, and zinc and iron react chemically to form a zinc-iron alloy layer and a pure zinc layer on the surface of the sheet. This coating is not only hard and wear-resistant, but also can protect the steel sheet substrate through sacrificial anodes when the zinc layer is partially damaged to prevent further corrosion. The surface of the sheet after hot-dip galvanizing presents a uniform silver-white luster, which is often used in outdoor building structures, traffic guardrails and other fields with high requirements for weather resistance.
Electroplating can give high carbon steel sheet different surface characteristics according to needs. In a specific electroplating solution, metal ions are deposited on the surface of the sheet through electrolysis to form different metal coatings such as chrome plating and nickel plating. Chromium plating can improve the hardness and wear resistance of the sheet surface, making it bright and not easy to adhere to dirt; nickel plating can enhance the corrosion resistance and weldability of the sheet, while improving the appearance texture. The advantage of the electroplating process is that the coating thickness is controllable and can achieve more complex surface decoration effects.
Chemical oxidation treatment can generate an oxide film on the surface of high carbon steel sheet, which plays a protective and decorative role. A specific chemical solution reacts with the surface of the sheet to form a dense oxide layer. Although this film is thin, it can effectively block the invasion of corrosive media. For example, blackening (also known as bluing) is a common chemical oxidation process. The surface of the treated sheet is uniformly black or blue-black, which not only enhances the rust resistance, but also has a unique appearance effect. It is often used in mechanical parts, tools and other products.
Phosphating can enhance the bonding between high carbon steel sheet and coating. The sheet is immersed in a solution containing phosphoric acid and phosphates, and a porous phosphating film is formed on the surface after a chemical reaction. This film can absorb the paint, so that the coating and the sheet form a mechanical bite, which significantly improves the adhesion and durability of the coating. At the same time, the phosphating film itself also has a certain rust resistance. It is often used as a pretreatment process before painting and is widely used in automobile manufacturing, home appliance production and other fields.
Shot blasting focuses on improving the surface roughness and cleanliness of high carbon steel sheet. Shot blasting uses a high-speed rotating impeller to project projectiles onto the surface of the plate, removing impurities such as rust and scale on the surface through impact force, and forming a uniform rough surface on the surface; sand blasting uses compressed air to spray sand particles onto the surface of the plate at high speed, which also achieves the purpose of cleaning and roughening. The surface roughness of the treated plate increases, which is conducive to the adhesion of subsequent coatings, and can eliminate the tiny stress concentration on the surface and improve the fatigue performance of the material.
These surface treatment methods have their own characteristics and applicable scenarios. In actual applications, they need to be comprehensively selected based on factors such as the use environment, performance requirements and cost budget of high carbon steel sheet to achieve the best protection and use effect.
