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Welding of cast iron.

Wednesday, October 6, 2010

Welding,CNC Lathe
Welding of cast iron.
the basic elements of cast iron are fe,c,and si. ni,cr,etc,are often added for special purposes.most welding of cast iron is repair work such as crack repairing during the structure's use and repair by build-up welding.welding of cast iron to fabricatite a structure is rare.welding of cast iron can be very difficult for the following reasons:

a.The heat affected zone becomes white cast iron.White cast iron is hard ,brittle,and the shrinkage due to weld heat is much larger than that of the base metal.this causes large residual stress and cracking often occur.
b.cast iron contains much carbon.this carbon reacts with oxygen in the air and generates co gas,which causes weld defects such as blowholes and pits.
c.Cast iron's low elongation,residual stress due to the casting process,and heat stress during welding accumulate,causing cracking not only at the weld joint but in the base metal as well.
d.Coarse graphite after prolonged heating and penetrated oil in the cast iron make welding difficult .weld defects easily occur.
When welding cast iron,preheating and post weld heating is applied to prevent cracks at the white iron zone and to minimize residual stress.When a welding electrode of cast iron or pure iron is used,a preheating temperature of 500-600 c or more is recommended,but attention must be paid to deformation in size and shape.When a welding electrode of pure Ni or Ni containing another metal is used,a preheating temperature of 100-300 c is applied to incriase wettability between the weld metal and the base metal.
Shielded metal arc welding (with covered electrode) and gas welding of cast iron are common.Covered electrodes are prescribed in JIS Z 3252:2001.


Buy Domain India August 8, 2011 at 6:31 PM  

I am not that much familiar with this welding information but I have interest to learn more. Thanks for sharing.
Buy domain India

Mig Welder November 29, 2011 at 10:49 PM  

Nice article on the welding of cast iron. Thanks for sharing.

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