Weld Cast Iron
Welding cast iron is a precision task that requires high heat, and often expensive equipment. You should not attempt it on the strength of reading a brief Internet article, no matter how informative. However, understanding the basics can help you prepare for a qualification course, or to make better decisions for welding projects run by qualified personnel under your supervision.
Contents
Steps
Temperature and Environment
- Keep the cast iron out of the range of 150 to 500 degrees Fahrenheit (65 to 260 Celsius). This is a danger zone for cast iron, during which it is the most unstable and difficult to work with. This will usually mean heating or cooling the iron before and during the work.
- Preheat the sections that require work to the {{safesubst:#invoke:convert|convert}} range (260 to 649 Celsius).
- Keep nearby iron cool, but not cold. If cold, you can sometimes run the machinery to get it up to the desired temperature.
- Keep your repair patch cool enough that you can touch it safety with your bare hand. Hotter patches can ruin the weld, and cold patches will take too long to heat up to welding temperature. Consult your engineering specifications documents to know the best temperature for the exact iron formula you are using in your project.
Welding
- Repair cracks and rips by attaching a cast part that serves as a patch between intact parts of the cast iron.
- Weld patches in place using short welds, about 1 inch (2.5 cm) long each. This will keep the nearby metal from overheating as you work.
- Use studding to reinforce major cracks. This technique involves drilling holes into the cast iron surface, then screwing the patch in place. You then weld the screws in place as part of the repair job.
- Expect to find small cracks in the iron when your welding is done. This is a normal and unavoidable part of welding cast iron. Use sealing compound for joints and sections that must be watertight.
Tips
- Always preheat or pre-cool cast iron using the same method throughout. Changing methods can cause stress and fractures in the cast iron. These may ruin your project, or be small enough to go unnoticed until the iron fails catastrophically during normal operation.
- Cast iron is typically higher in carbon than steel. This makes the iron brittle, and more difficult to weld than other industrial metals.
Warnings
- Keep fire suppression handy when working with your welding rig. Although cast iron is not flammable, you are -- and so are many of the materials that are part of the welding rig.
Things You'll Need
- Welding rig
- Safety goggles
- Cast iron patches
- Welding gloves
- Welding apron or work suit
