Problems and Solutions in the Application of Tinplate

Problem Manifestations:

• Localized Corrosion (Pit Corrosion, Crevice Corrosion): The base iron is exposed at points where the tin plating is damaged, leading to electrochemical corrosion in humid or electrolyte environments.
• Overall Rust: High humidity in the storage or use environment causes oxidation of the tin plating or rusting of the base iron.
• Content Corrosion: Acidic or sulfur-containing foods (such as tomato sauce, meat) may corrode the tin plating, leading to tin dissolution or sulfide spots.

Solutions:

• Optimize Plating Process: Increase the thickness of the tin plating or use differential tin plating (thicker inner layer, thinner outer layer) to improve corrosion resistance.
• Inner Wall Coating Protection: For corrosive contents, apply an organic coating (such as epoxy phenolic resin, acrylic resin) to the inner wall.
• Environmental Control: Keep the storage environment dry (relative humidity ≤60%) and avoid excessive temperature differences that may cause condensation.
• Alloy Layer Treatment: Form a dense FeSn₂ alloy layer through a remelting process to enhance corrosion resistance.

Problem Manifestations:

• Melting of the tin layer during welding leads to electrode contamination, resulting in weak solder joints or missed welds.
• The weld seam is prone to rusting or leakage.

Solutions:

• Use high-frequency resistance welding (TFS chrome-plated iron is more suitable): Chrome-plated iron has better weldability than tinplate.
• Laser welding or TIG welding: Use more precise welding processes for high-requirement products (such as chemical tanks).
• Weld seam repair coating: Apply a repair coating to the inner wall weld seam after welding to prevent corrosion.