In the past, most welders would never even think about TIG welding cast iron due to the unpredictability of such repairs but times have changed and it can now be done albeit with utmost care.
What Rods Should I Use for Cast Iron Welds
Welding cast iron was difficult because iron contains carbon which makes it extremely hard and suffers from cracking problems as cast iron is very brittle. Instead of bending when heated, it breaks. Nickel rods, also called Ni rods are the most preferred and popular arc welding rods for TIG welding cast iron. However, aluminum bronze is proposed as a very good choice for TIG welding cast iron. Some of the reasons this is considered the perfect choice for cast iron welding include: The high carbon content does not cause unwarranted hardening of the weld deposit. The metal cannot crack easily near the weld are because the solidifying weld metal used does not have high shrinkage stresses. The TIG welding rods, in this case, aluminum bronze, are almost as strong as steel and ensure that the welded area holds and the TIG welding cast iron happens as planned.
Tips That Make A Difference
When welded using AC, the aluminum bronze rods do not all get diluted from the iron base metal because they wet easily and thus can flow with ease. In terms of cost, the aluminum bronze TIG welding rods are much cheaper than the Nickel rods which can make TIG welding cast iron procedure pocket friendly. TIG welding cast iron requires absolute concentration and careful temperature monitoring to limit the possibility of cracks in the brittle cast iron. The process to do this effectively follows:
- Make sure the surface of the weld location is thoroughly cleaned to get rid of impurities like dust and rust. A clean surface will aid in ensuring a strong weld formation. The parts should then be pre-heated to prevent a possibility of the cast iron cracking. If the procedure is projected to take longer then the cast iron should continue to be heated, at a constant rate during this duration, since it is very sensitive to temperature shifts.
- For the TIG welding cast iron procedure, select the aluminum bronze if the iron being welded will not experience further heating during its use afterward but if it will, go with the Nickel filler rods as they can withstand heat, an example of this is engines. The use of low current is recommended to discourage residual pressure and stress from building up. Do many short welds instead of a continuous one to regulate the temperature then hit the weld with a hammer to relieve the accumulating pressure.
- After completing the welding, the iron should be left to cool down slowly to prevent hardening. To achieve this efficiently, the part should be put in an oven then the temperature can be lowered slowly as time goes by. This constitutes a perfect TIG welding cast iron mission.