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Welding of copper and copper alloys.

Saturday, October 2, 2010

Welding,CNC Lathe
Copper is classified as either electrolytic copper,which includes a small amount of oxygen and has high electric conductivity,or deoxidized (o oxygen free) copper.
Electrolytic copper easily develops blowholes and cracks during welding,but deoxidized copper or oxygen free copper are suitable for weld structures.
Copper (Cu) alloy are classified as aluminium bronze,brass,phosphor bronze,cuproniccle,etc.
And are widely used in various fields for their anti-corrosive,wear resistant,or heat resistant properties.

As welding of Cu and Cu alloys is more difficult than that of steel,the following points should be noted:
A.The melting point of pure copper is 108 C.The melting points of Cu alloys are also much lower than those of steel.When welding using flux is performed,the melting point of the slag is apt to be high and slag inclusions may easily occur.
B.Due to high thermal conductivity (8 times that of mild steel),weld heat expands quickly to the surrounding base metal.
Extensive preheating may be required to obtain the necessary fusion and penetration.
Consequently,the heat affected zone is much wider than that of mild steel.
C.Due to a large coefficient of thermal expansion,large distortions or cracks can easily occur during welding.This difficulty is most often observed during the welding of thick and high restraint joints,or when welding copper alloys.
D.Most Cu and Cu alloys do not make a solid phase transformation .Crystal grain sizes are apt to be coarse,and strength and elongation of weld joint low.
E.Hydrogen in copper weld metal reacts with oxygen during solidification,becomes water vapor,and may cause blowholes.
F.Elements which reduce welding performance,such as Pb,Sn,or Bi,are often included in Cu alloys.They can cause cracks or brittle metal.When brass is welded,considerable Zn vapor and fumes are generated.
G.When Cu and its alloy are welded,cares should be taken for welder to prevent a metal fever.


Mig Welder November 29, 2011 at 10:51 PM  

Thanks for this, any tips for MIG welding copper? What welding supplies I would need as well as the best MIG welder to use?

Thanks in advance.

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