The Core Challenges of Copper Welding

Copper (pure copper) is widely used in industries such as power generation and refrigeration due to its excellent electrical and thermal conductivity. However, its high thermal conductivity (approximately eight times that of steel), large coefficient of thermal expansion, and tendency to oxidize make welding a technical challenge. Selecting the appropriate method and controlling process details are critical.

Oxy-acetylene Gas Welding: An Economical and Flexible Solution

This method uses an oxygen-acetylene flame (approximately 3100°C) in conjunction with flux (such as CJ301) for welding. Its advantages include simple and portable equipment, making it particularly suitable for thin plates ≤3mm and on-site repairs. The flame also provides built-in preheating functionality. However, its disadvantages include limited protective effects, a wide heat-affected zone, and lower efficiency. It is suitable for thin plate butt welding or pipeline repairs with lower quality requirements.

TIG Welding: The Preferred Choice for High-Quality Welding

Under pure argon gas protection, a tungsten electrode arc melts the base material while adding filler wire (ERCu). Its primary advantage is excellent inert gas protection, resulting in high weld purity, aesthetic weld bead formation, narrow heat-affected zone, and minimal distortion. It can weld thin, medium, and thick plates as well as pipes in all positions. However, it has high equipment costs and stringent operational skill requirements. It is the ideal choice for critical electrical components, pressure vessels, and products with high aesthetic requirements.

Shielded Metal Arc Welding (SMAW): Solution for Thick Plates and Harsh Environments

Welding is performed using coated electrodes (e.g., T107). The equipment is simple, has good wind resistance, and achieves deep penetration, making it suitable for plates thicker than 6 mm and outdoor operations. However, it has drawbacks such as unstable protection, prone to porosity, significant spatter, poor weld bead formation, and frequent electrode replacement, resulting in low efficiency. It is suitable for large structural components with low aesthetic requirements or when gas protection conditions are unavailable.

Brazing: Low-temperature connection solution

Use copper-phosphorus/silver-based brazing alloys to connect materials at temperatures below the base material's melting point. The key feature is that the base material does not melt, resulting in minimal thermal deformation. It can connect dissimilar metals like copper and steel, and the process is simple. However, the joint strength is lower than that of fusion welding, and specific lap or socket joint designs are required. It is suitable for electrical contacts, refrigeration piping, thin-walled components, and applications sensitive to deformation.

Key Processes and Selection Recommendations

Successful welding requires:

——Thoroughly cleaning oil and oxide residues from the joint before welding

——Preheating at 350–600°C for thicknesses >4 mm

——Using ≥99.99% high-purity argon gas for TIG welding

——Using high current (30–50% higher than steel welding) for rapid welding

The optimal method depends on requirements:

✅ Prefer TIG welding: high-quality thin to medium-thick plate welding

✅ Oxy-acetylene welding: low-cost thin plate repair

✅ Arc welding: thick plates in harsh environments

✅ Brazing: dissimilar metals/low-temperature connections

Select flexibly based on workpiece thickness, quality requirements, and construction conditions.