Characteristics of cast iron technology
Cast iron is more dilute than steel and the transition from solid to liquid as well as from liquid to solid occurs very quickly, so welding cast iron should only be soldered at the position of solder.
When welding the cast iron, the gas molecules do not completely get rid of the molten metal, so the welds usually have steam holes.
In the liquid state, the iron is susceptible to oxidation so that the oxide at a high melting point causes the welded or welded iron to melt.
The ductility of cast iron is low, so it is easy to crack if it is heated unevenly.
Cast iron welds are susceptible to being turned white due to burning of silicon in cast iron.
Cast iron welding technique
Welding technology using gas welding technology
In general, welding of welded iron should conduct welding.
a) Prepare the weld
Depending on the thickness of the weld that may not be bevelled or bevelled.
Do not chamfer when solder thickness is less than 4mm.
Bevelled when solder thickness exceeds 4mm. Bevelled corner (70 ÷ 90) degrees
After preparation is done to carefully clean the welding edge and then conduct welding.
Prior to welding, the preheating of the welding material should be preheated
Preheating temperature depends on the organization of the cast iron, the preheating temperature is usually 500 to 700 degrees Celsius.
Select welding flame and flame capacity:
Flame-welded carbon flame is a carbonization flame with flame power of 1mm. Weld thickness is:
W = (100 ÷ 120) (liter / hour)
Use cast iron or brass rods or brass rods
Cast iron welded cast iron components
Drugs for welding cast iron are boiler (Na2B4O7) or mixture of coconut with copper sulphate and silica: 50% Na2B4O7 + 47% CuSO4 + 3% SiO2
After welding, it must slow down the weld
If the joint has a crack, the cracks must be treated before welding, just like welding the arc with arc.
Welding of non-critical structures, small in size and can and can be expanded freely, use a cast iron rod and pre-welding without heating pre-welding