Welding cast iron is a precision task that requires a lot of heat, and often expensive equipment. You shouldn't just get down to business after reading an article on the internet, no matter how complete this is. However, understanding the basics of the process can help you prepare for a training course, or make better decisions for welding projects performed by qualified personnel under your supervision.
Steps
Method 1 of 2: Temperature and Environment
Step 1. Keep cast iron outside the 65 to 260 ° C (150-500 degrees Fahrenheit) temperature range
This is a dangerous area for cast iron, where the material is unstable and difficult to handle. To do this you will usually have to heat or cool the metal before and during work.
Step 2. Preheat the sections to be welded, bringing them to temperatures between 260 and 650 ° C
Step 3. Keep the surrounding material cooler, but not cold
If it gets cold, you could use machinery to bring it back to the desired temperature.
Step 4. Keep the repair pad cool enough to safely touch it with your bare hands
Warmer plugs could ruin the solder, while it would take too long to bring cold plugs to soldering temperature. Consult the specific documentation to know the exact temperature to work at, for the material you are using in your project.
Method 2 of 2: Welding
Step 1. Repair cracks and fractures by using pieces of cast iron as "patches" to keep the two parts of the underlying material connected
Step 2. Secure the dowels in place using short welds, approximately 2.5 cm each
This way you will avoid overheating the surrounding material.
Step 3. Use studs to reinforce larger cracks
This technique consists of drilling the base material to be repaired, and then screwing the dowel in its place. You can then weld the screws to complete the job.
Step 4. Expect to find cracks in the metal when you have finished welding
This is normal and unavoidable in cast iron welding. Use a sealant for welds and connections that need to be airtight.
Advice
- Pre-heat or pre-cool cast iron always using the same method while working. Changing the method could cause stress and cracks in the cast iron, which could ruin your project, or be so small that they go unnoticed, leading to catastrophic failure of the metal under stress.
- Cast iron generally contains more carbon than steel. This makes it brittle and more difficult to weld than other industrial metals.
