Cast iron welding technique

Cast iron welding technique

Date 06/05/2019
In welding techniques, cast iron is one of the most difficult and complex techniques. However, it is not unworkable if the worker notes the following factors.
Unlike other welding methods, cast iron is used mainly in repairing machines, tools, repairing foundries, faulty products after casting, etc., are rarely used to connect the details. Private manufacture such as aluminum, iron or stainless steel welding ...
Common difficulties when welding cast iron:
- The characteristics of cast iron are hard and crispy. In metals, the flexibility of the cast iron is relatively low. Experimental review of the towing map of the cast iron has virtually no clear flow.
Gangs are very sensitive to heat and cold velocity is fast, so it is easy to change the organization during welding as well as the cooling after welding, resulting in welding or cracks.
- Cast iron alloy products are diverse in chemical composition, so it is difficult to determine the welding and heating conditions.
- It is difficult to perform the welding of cast iron as it is in cast iron liquids with high dilution.
Types of processes apply to cast iron welding
1. Cold welding process
Proceed in the manner of welding each piece from 2-3cmm. Allow the weld to cool completely (can be directly touched) then continue welding.
Sequence welding should follow the symmetric welding method or the reverse segment.
2. Hot welding process
Heat the solder to about 600 - 6500C. At the same time in the welding process must also constantly keep heat. The process of cooling the solder after welding should maintain a speed of around 1200C / s (in the furnace) or use an outer sheathing shell (difficult to apply to large, bulky objects) or may be buried in dry sand .
Tip to know: heating the iron to see when the red is ripe. Or use dry pine blades to blow up the heat, if there is annihilate fly out.
 
Selection of welding materials
Need to choose the right material for welding the cast iron. Welding materials need high ductility. Nickel usually accounts for 90%.
For welding rod, commonly use copper or stainless steel. It is best to use nickel and copper alloys. When soldering, use a carbonization flame to offset the carbon content of cast iron losses due to fire.
Some notes when welding cast iron:
When soldering, the excess residuals in the cast iron is quite large due to the characteristics of pig iron is brittle and hard so it is easy to appear cracks during use, especially the welding process. One measure to avoid tearing the cracks is to block the two ends of the weld before welding. The next step is welding in the order from the crack to the end, then fill the hole 2 holes.
When soldering, it should be noted that sealing in the wind if not during heating and welding will increase the phenomenon of rupture.
For high hardness solders, a local heating method may be employed.
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