As a metallurgical engineer with extensive experience in materials joining, I can provide you with a detailed answer regarding the brazing of copper to stainless steel.

Brazing is a process where two materials are joined together by melting and flowing a filler metal into the joint, the filler metal having a liquidus above 450°C and below the solidus of the base metal. It is a versatile technique that can be used to join a wide range of materials, including copper and stainless steel.

Copper is a ductile metal with excellent thermal and electrical conductivity. It is commonly used in plumbing, electrical wiring, and heat exchangers. Stainless steel, on the other hand, is a family of iron-based alloys that contain a minimum of 10.5% chromium, providing resistance to corrosion and staining. It is widely used in construction, automotive, and food processing industries due to its durability and low maintenance.

When it comes to brazing copper to stainless steel, there are several factors to consider:


1. Material Compatibility: Copper and stainless steel have different thermal expansion coefficients and corrosion resistance properties. This can lead to issues such as galvanic corrosion when joined without proper precautions.


2. Filler Metals: The choice of filler metal is crucial. It should have a melting point that is higher than the base metals to prevent melting of the base metals during the brazing process. Commonly used filler metals for brazing copper to stainless steel include silver-based and nickel-based alloys.


3. Flux: Flux is essential for brazing as it cleans the surfaces to be joined and prevents oxidation during the heating process. For joining copper to stainless steel, a flux that is compatible with both materials must be used. The use of paste flux should be sparing to avoid excessive residue that can lead to corrosion or other issues.


4. Brazing Process: The brazing process involves heating the joint to a temperature where the filler metal melts and flows into the joint. This can be achieved using various heat sources such as a propane torch, as mentioned in the reference material. However, it is important to control the temperature and heating rate to ensure proper wetting and flow of the filler metal without damaging the base metals.


5. Post-Braze Cleaning: After brazing, it is important to clean the joint to remove any residual flux and oxidation products. This can be done using a variety of cleaning agents and methods, depending on the specific materials and the brazing process used.


6. Testing and Inspection: Finally, the brazed joint should be tested and inspected to ensure it meets the required mechanical and functional specifications. This may involve visual inspection, mechanical testing, and non-destructive testing methods.

In conclusion, brazing copper to stainless steel is feasible and can be done effectively with the right materials, processes, and precautions. It requires careful consideration of material compatibility, filler metal selection, flux usage, brazing process control, and post-process cleaning and inspection.

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Soldering, Brazing, and Welding Tips. Soldering with a propane torch is the easiest way to join copper and brass. You can even use solder to join copper or brass to stainless steel, you just need the proper flux. ... If you must use a paste flux, use it sparingly.read more >>