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WELDING THROUGH FORGING

V.Ryan © 2020

 
Welding can be achieved through forging, by heating up both pieces to very high temperatures (white heat indicator colour) and then ‘hammering’ them together. Mild steel requires a slightly lower temperature, yellow heat approaching white heat. Getting the temperature right is very important. If the temperature is even slightly lower than it should be, hammering will not produced a welded joint. However, if the temperature is too high, the metal will be damaged through burning.
 

It is important to use flux on the surfaces to be welded together. The flux prevents oxidisation taking place, by providing a protective coating called ‘slag’, with prevents oxygen in the air reaching the metal’s surface. Borax is used as a flux for mild steel and sand for wrought iron.

The fire in the Blacksmith’s hearth, must be carefully maintained, in order to achieve the high temperatures required for welding. Also, the heart of the fire must be free of ‘clinker’ (the waste produced by heating coke).

The welding process starts at the centre of the joint, with the Blacksmith working outwards. This displaces any slag / impurities. Working from the outside of the joint inwards, has the potential to lock in any impurities / slag, as hammering progresses. This could lead to poor and weak welded joint.

 
 
 
 
 
It may appear that the butt weld is the easiest to carry out. However, this is not the case. Both surfaces must be forced together whilst hammering takes place, all at the same white heat.
 
 
 
SCARF WELDING
 
  The ‘scarf weld’, is the most popular way of joining two pieces of metal. The ends to be joined are prepared carefully by ‘upsetting’. They are then heated to yellow/white heat , sprinkled with flux (borax for mild steel) and placed on the face of the anvil.
Hammering starts at the centre of the joint, forcing impurities / slag out of the joint.
Once the joint is made, the Blacksmith concentrates on shaping / forming the joint, so that it is accurate and smooth.
 
 
 
 
 
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