Copper Alloy Welding Wire

A1: High-performance copper alloy welding wire is a welding material based on copper, with added alloy elements such as silicon, tin, aluminum, and nickel. It has excellent electrical conductivity, thermal conductivity, and targeted performance (such as corrosion resistance, high strength), and is specially used for welding copper alloys and related dissimilar metal connections.

A2: In terms of composition, copper alloy welding wire takes copper as the matrix, and the added elements are mainly to improve weldability and specific properties; nickel alloy welding wire is based on nickel, with high content of chromium, molybdenum and other elements. In terms of performance, copper alloy welding wire is superior in electrical and thermal conductivity, while nickel alloy welding wire is better in high-temperature resistance and strong corrosion resistance. In application, copper alloy welding wire is suitable for medium and low temperature, conductive and heat exchange scenarios, while nickel alloy welding wire is used in high-temperature and extreme corrosion environments.

A3: For brass (copper-zinc alloy), choose copper-silicon welding wire (such as ERCuSi-A) to avoid zinc evaporation causing pores; for tin bronze, match copper-tin welding wire (such as ERCuSn-C) to ensure consistent performance; for aluminum bronze, select copper-aluminum welding wire (such as ERCuAl-A2) to improve joint strength; for cupronickel, use copper-nickel welding wire (such as ERCuNi) to maintain corrosion resistance.

A4: TIG (tungsten inert gas welding) is suitable for thin-walled parts and precision welding, with stable arc and good 成形；MIG (metal inert gas welding) is applicable to medium and thick plates and mass production, with high efficiency; for thick-walled copper alloy structural parts, submerged arc welding can also be used, but it is necessary to match special fluxes to prevent oxidation.

A5: Thoroughly remove oil, oxide scale, and moisture on the surface of the base metal—mechanical grinding (using stainless steel wire wheels) or chemical cleaning (using dilute sulfuric acid for pickling) can be used; for aluminum bronze with high aluminum content, it is necessary to remove the dense oxide film on the surface to avoid incomplete fusion.

A6: Common defects include pores (mainly caused by hydrogen absorption or evaporation of alloy elements such as zinc), incomplete fusion (due to poor wettability or insufficient heat input), and hot cracks (caused by segregation of low-melting-point impurities).

A7: Strictly clean the base metal to remove oil and moisture (sources of hydrogen); use high-purity argon (purity ≥99.99%) as shielding gas to prevent air intrusion; control the welding heat input—avoid excessive temperature causing evaporation of zinc, tin and other elements.

A8: The current is mainly determined by the wire diameter and base metal thickness. For example, a 1.2mm diameter wire for thin copper plates (thickness 1-3mm) uses a current of 120-180A; for thick plates (thickness >5mm), the current can be increased to 200-300A. Note that copper has high thermal conductivity, so the current should be 10-15% higher than that of carbon steel of the same specification to ensure sufficient melting.

A9: Store in a dry and ventilated environment with a relative humidity not exceeding 60% and a temperature of 15-30℃; keep the packaging sealed to prevent moisture absorption (moisture will cause pores during welding); avoid contact with corrosive gases (such as sulfur dioxide) to prevent surface oxidation of the welding wire.

A10: For general structural parts, post-weld heat treatment is not required; for high-precision parts (such as electrical connectors) that require stable performance, stress relief annealing can be performed at 250-350℃ for 1-2 hours to reduce residual stress; for aluminum bronze welded joints, aging treatment at 400-450℃ can improve hardness.

A11: Yes. It is suitable for welding copper and low-carbon steel, copper and nickel-based alloys, etc. For example, ERCuNi welding wire can be used for welding copper and cupronickel; when welding copper and steel, choose copper-silicon welding wire with good compatibility, and control the heat input to avoid brittle phases.

A12: It may be that the welding current is too low or the welding speed is too fast, resulting in insufficient heat input; the oxide film on the base metal surface is not completely removed, affecting the wetting of the molten metal; or the welding gun angle is improper, causing the arc to deviate from the fusion zone.

A13: Select welding wire with corrosion-resistant elements (such as nickel, aluminum); control welding heat input to avoid overheating and grain coarsening (coarse grains are more likely to corrode); perform surface treatment after welding, such as passivation or electroplating (chromium or nickel plating) to form a protective layer.

A14: High-purity argon (≥99.99%) is usually used; for thick plates, adding 5-10% helium to argon can increase arc temperature and improve penetration; if the shielding gas purity is insufficient or the flow rate is too low, it will cause oxidation of the weld, forming a black oxide layer and reducing joint performance.

A15: Conduct tensile and bending tests to check mechanical strength; for electrical parts, test the electrical conductivity of the joint (using a conductivity meter); for corrosion-resistant parts, perform salt spray tests or immersion tests in specific media (such as seawater, brake fluid); metallographic analysis can also be used to observe internal defects.

A16: Use small-diameter welding wire (0.8-1.2mm) and low current to avoid burning through; adopt short-arc welding to reduce heat input; use fixtures to fix the workpiece to prevent deformation caused by uneven heating; choose a welding method with good control (such as TIG welding).

A17: If stored in a sealed and dry environment, it can be used within 1-2 years; if the storage time exceeds 2 years, check the surface condition—if there is no oxidation, discoloration, or moisture, it can be used after drying; if there is obvious oxidation (such as green rust), it is recommended to polish the surface or replace it.

A18: For light oxidation, use a stainless steel wire brush or sandpaper to polish it; for severe oxidation, use chemical pickling (use dilute nitric acid solution for copper-silicon, copper-tin welds; use dilute sulfuric acid solution for aluminum bronze welds), then rinse with clean water and dry.

A19: Copper-silicon welding wire (ERCuSi-A) has good fluidity and is mainly used for welding brass and copper-silicon alloys, suitable for structural parts with high strength requirements; copper-tin welding wire (ERCuSn-C) has good wear resistance and is suitable for welding tin bronze, such as bearings, gears and other friction parts.

A20: Adopt symmetrical welding sequence (weld from both sides alternately) to balance stress; use intermittent welding instead of continuous welding to reduce heat accumulation; pre-set reverse deformation (bend the workpiece slightly in the opposite direction of deformation) before welding; cool the weld with a copper heat sink during welding (for thin plates).

A21: The wire feed wheel pressure is too high, causing the wire to be crushed; the wire feed hose is bent or blocked, increasing resistance; the welding wire itself has quality problems (such as cracks, uneven diameter); or the current is too high, causing the wire to overheat and become brittle.

A22: Increase the shielding gas flow rate (by 20-30% compared to normal temperature) to prevent air intrusion due to thermal convection; appropriately reduce the welding speed to ensure sufficient fusion (high temperature accelerates heat dissipation); preheat the base metal slightly (50-100℃) to avoid excessive temperature difference.

A23: Too fast a speed will lead to insufficient fusion and shallow penetration; too slow a speed will cause overheating, resulting in grain coarsening of the weld and reduced mechanical properties; the speed should be matched with the current and wire feeding speed, generally controlled at 50-150mm/min (adjust according to plate thickness).

A24: First, use a grinder to remove the pore area (grind to a depth of at least 1mm around the pores to ensure complete removal); clean the repair area with acetone to remove debris; use small current and short arc for repair welding, and fill the weld step by step; after repair, check with non-destructive testing (such as penetration testing).

A25: The surface should be smooth and free of burrs, cracks, or oil stains to ensure smooth wire feeding; the diameter should be uniform (tolerance within ±0.02mm) to avoid unstable current caused by uneven wire feeding; for coated welding wire (if any), the coating should be uniform and not fall off.

A26: Prioritize welding wire with good airtightness (such as ERCuSn-C) to prevent refrigerant leakage; select welding wire with high thermal conductivity to avoid affecting the heat exchange efficiency of the pipeline; ensure compatibility with refrigerants (such as R32, R410A), and the weld should not react with the refrigerant.

A27: It is mainly caused by the segregation of low-melting-point impurities (such as lead, sulfur) in the weld, forming a low-melting-point eutectic; excessive welding stress (such as rigid fixation of the workpiece) can also induce cracks; or the welding wire and base metal have large differences in thermal expansion coefficients.

A28: Select welding wire with low impurity content (lead <0.01%, sulfur <0.01%); avoid excessive heat input to reduce the segregation of low-melting-point substances; design reasonable grooves to reduce weld restraint; perform post-weld stress relief treatment if necessary.

A29: Solid welding wire has high purity and is suitable for precision welding (such as electrical parts); flux-cored welding wire contains flux in the core, which can remove oxides during welding, suitable for thick plates and outdoor welding; solid welding wire requires strict shielding gas protection, while flux-cored welding wire has better adaptability to harsh environments.

A30: If the undercut is shallow (depth <0.5mm), it can be repaired by grinding and then filling with a small amount of welding wire; for deep undercut, first grind to remove the undercut area, then re-weld with adjusted parameters (reduce current or increase wire feeding speed) to avoid reoccurrence.

A31: In low-temperature environments (below 0℃), the base metal should be preheated to 50-100℃ to avoid cold cracks caused by rapid cooling; in high-temperature environments (above 30℃), strengthen ventilation and cool the workpiece if necessary to prevent overheating; high temperature and high humidity environments need to pay attention to moistureproof of welding wire and base metal.

A32: Select welding wire with high electrical conductivity (such as ERCuSi-A, ERCuSn-C); control welding heat input to avoid excessive oxidation (oxidation will reduce conductivity); reduce the content of impurities in the weld (such as phosphorus, lead), which will affect electron transmission; post-weld annealing can improve conductivity by eliminating internal stress.

A33: The fixture should have good thermal conductivity (such as copper or aluminum alloy fixtures) to help dissipate heat and reduce workpiece deformation; the clamping force should be uniform to avoid stress concentration; the contact surface with the workpiece should be smooth to prevent indentation on the workpiece surface.

A34: Prioritize ERCuNi welding wire with seawater corrosion resistance; ensure that the welding wire has good fluidity to fill the pipeline weld completely (prevent seawater leakage); the weld should have sufficient strength to withstand the pressure of seawater circulation, and the alloy elements should not react with marine organisms (avoid biological fouling).

A35: In dry and clean indoor environments (such as electrical cabinets), the service life can reach more than 20 years; in humid atmospheric environments (such as coastal areas), it can be used for 10-15 years with proper anti-corrosion treatment; in seawater or corrosive media, the service life is 5-10 years (depending on the corrosion resistance of the welding wire and surface protection measures); in high-frequency vibration environments (such as automotive parts), it is 8-12 years, mainly affected by fatigue strength.