Welding Copper Alloys: Factors, Defects, and Techniques
Factors Influencing Weldability of Copper and Alloys:
High thermal conductivity, high coefficient of expansion, selection of the design of the union, position of welding, surface condition, vaporization of elements.
Gases Used in Welding:
Oxygen: As fuel gas, oxygen is used. If used, the temperatures reached would be 800 to 1000 º C. As fuel gas, hydrogen, natural gas, propane, or other fuels can be used. However, the acetylene flame with oxygen achieves higher temperatures, providing greater heat than any other gas.
Typical Defects in Welds:
Lack of cleanliness. Deformation of the pieces. Variation of chemical composition caused by the reaction of the flame to the base metal.
POROS: Selection of inappropriate calls. Lack of cleaning the base metal. Lack of fusion or penetration. Excessive welding speed. Separation scarce in the root. Slag inclusions by poor cleaning.
Mixing Chamber:
In the mixing chamber, intimate combustion occurs. There are two types: OVERPRESSURE: Oxygen and gas go to the same pressure and speed. INJECTION OR SUCTION: The fuel gas is sucked oxygen flow by high velocity. For this system, a nozzle is used. It is used when the fuel gas is supplied at a pressure too low to produce proper combustion.
Nozzles:
They are interchangeable nozzles that adjust at the end of the torch or spear. They control the flow of gas through the diameter of the exit diameter. The following precautions should be observed:
- Should be adhered to keep clean and in good threads and locking surfaces to prevent leaks and flash back.
- Clean the mouthpiece with appropriate reamers.
Anti-Flashback Valve:
Can cause an explosion, therefore, it is from: The entry of oxygen into the canal and that provides the acetylene cylinder. A pullback in the torch flame, as mangu, tube rials, cylinders, or deposits. And then provision during a flash back. These valves have security elements: q-return valve allows the passage of gas in a one-way q microporaso Sintering backward off a flame, q Thermal cutting valve closes to detect a temperature rise.
Gases Used in Welding:
As oxidizing gas, oxygen is used. If used, the temperatures reached would be 800 to 1000 º C. As a combustible gas, hydrogen, natural gas, propane, or other fuels can be used. However, the acetylene flame with oxygen achieves higher temperatures, providing greater heat than any other gas.
Fusion Welding of Copper and Alloys:
The most used electrodes are coated MIG TIG and oxygenated. Welding copper: The biggest problem is the absorption of oxygen from the air or the presence of this in the weld. For this reason, the non-deoxidized coppers cannot be welded by fusion processes as cracks occur; they will process q welded by solid-state welding, or brazing and friction. In fusion welding x cords are deve avoid oscillation. The most used are TIG (argon or argon + helium) MIG (=). Welding of Brass: The biggest problem is the vaporization of zinc is a metal that melts and vaporizes q at very low temperatures and the heat of the arc welding or a heat source used for welding, zinc not only refine but q lo vaporizes out of the melt-shaped metal vapors q cause fever. Welding of bronzes: The most important problem is the ease of formation of cracks, we recommend: q Make a hammer to reduce the stresses. The melt deve ser pekeño, was done through TIG, MIG or a coated electrode is not recommended for welding oxygenated.
Soft Brazing of Copper and Alloys:
Brazing: Most of the copper and its alloys can be welded satisfactorily by any of the brazing processes. It presents great advantages, reduces distortion, and avoids the drawbacks of the copper-containing oxygen. This advantage carries less danger of volatilization of minor elements. Soldering: The commercial copper and its alloys can be perfectly joined together by welding.