How to overcome the challenges encountered in the welding process of Copper-Nickel Alloy Materials?

When welding Copper-Nickel Alloy Materials, a series of challenges will be encountered, mainly including the high thermal conductivity of the alloy, easy oxidation, evaporation of alloy components, and welding cracks.
1. Choose the right welding method
TIG welding (argon arc welding):
Suitable for welding thinner copper-nickel alloy plates.
Use inert gas (usually argon) to protect the weld to avoid the influence of oxygen and other impurities on the welding quality.
High-quality welds can be achieved by precisely controlling welding parameters.
MIG welding (gas metal arc welding):
Suitable for welding thicker copper-nickel alloy plates.
The weld is also protected by inert gas, and the welding material is provided by automatic wire feeding.
Higher welding speed and efficiency, suitable for mass production.
Resistance welding:
Suitable for assembly and connection of copper-nickel alloys, especially suitable for mass welding on production lines.
Welding is achieved by heating and applying pressure, no filler material is required, and the welding cost is low.
2. Preparation before welding
Cleaning the weld:
Before welding, thoroughly clean the welding area to remove grease, oxides and other impurities on the surface. This helps improve welding quality and reliability.
Cleaning can be done with chemical cleaning agents or mechanical methods such as grinding.
Preheating:
For thicker copper-nickel alloy plates, preheating can reduce thermal stress and cold cracks during welding.
The preheating temperature should be determined according to the thickness and specifications of the material, usually between 200°C and 400°C.
3. Control during welding
Gas protection:
In TIG welding and MIG welding, ensure that the flow of inert gas is sufficient to fully protect the weld from oxygen and other impurities.
Check the accuracy of the gas flow meter regularly to ensure a stable gas supply.
Welding parameters:
Determine the appropriate current, voltage and welding speed according to the thickness and requirements of the welding material.
Typically, thinner plates require lower current and voltage, while thicker plates require higher current and voltage.
The welding speed should be moderate. Too fast may lead to a decrease in weld quality, and too slow will increase the heat-affected zone.
4. Prevent the evaporation of alloy components
Use silicon-containing welding wire:
Use with borax-containing solvent to hinder the evaporation of easily evaporable elements such as Zn.
The silicon element in the silicon welding wire can form compounds with other elements in the alloy to reduce evaporation losses.
Control welding temperature:
Avoid excessively high welding temperature to reduce the evaporation of alloy components.
The welding temperature can be controlled by adjusting welding parameters (such as current, voltage and welding speed).
5. Prevent welding cracks
Reduce stress concentration:
Try to use symmetrical welding sequence and uniform welding speed during welding to reduce the concentration of welding stress.
For multi-layer welding or multi-pass welding, attention should be paid to the control of interlayer temperature and the arrangement of welding sequence.
Choose suitable welding materials:
Choose welding materials with similar chemical composition to the parent material and good welding performance for welding.
The content of impurity elements in the welding material should be controlled at a low level to avoid the formation of low-melting eutectic materials that cause welding cracks.
6. Inspection and treatment after welding
Welding quality inspection:
After welding, welding quality inspection should be carried out, including visual inspection, penetration inspection, X-ray inspection, etc.
Select appropriate inspection methods according to welding requirements and standards, and perform further repairs or treatments based on the results.
Heat treatment:
For some workpieces that need to eliminate welding stress, heat treatment (such as annealing) can be performed to reduce welding stress and improve the performance of the welded joint.