How to weld Cast Iron

Cast Iron Electrodes

  

Hello everyone and welcome to the first article of the year 2020. In this article, I will teach you how to weld Cast Iron as this difficulty is faced not only by amateur welders but professional welders also face the same problem.
In-house welding of Cast Iron can save time and money but there are so many challenges, as they are very difficult to weld but there are certain techniques and proper process which makes welding Cast Iron less difficult.
Cast Iron is the family of Iron-carbon alloys. There are a variety types of Cast Iron and among the most common use is of Grey Cast Iron. Cast Iron has a carbon content of 2%-4% roughly 10 times as much as of most steels which makes Cast Iron welding difficult. The high carbon content uses the carbon to create the flakes of graphite.

GRINDING PROCESS

The first step is the grinding process. After Grinding the oil, dust, grease, etc. should be cleaned perfectly. After the above process is done, the next step is to make U groove weld. “A channel in the surface of a workpiece or an opening between two joint members providing space to contain weld metal.” To know more about Grooves, watch this video.
Before welding, the material should be pre-heated. Do not overheat the CI as it will result in a crack as Cast Iron is a crack sensitive material. Pre-heating temperature must be between 200°C to 300°C. The advantage of pre-heating is if oil or grease is attached then it will get removed during the pre-heating process.

SELECTION OF WELDING ELECTRODE

Now comes the important step which is the selection of welding electrode and amps. Nickel content electrode should be used. Use SME A15 pure nickel welding electrode for single-pass, high dilution weld. For multiple-pass welds SME A19 ferronickel welding electrode is suitable. Amps should be 86-90amps DCEP.
As mentioned earlier regarding the graphite flakes, due to graphite, chances of slag inclusion is higher. Clean the slag in between the welding process and peen each weld bead. The perfect angle for welding Cast Iron is a 90° angle. Got a little bored by reading the whole process? Watch this video of Cast Iron Wheel Repair to understand the process clearly.

COLD WELDING PROCESS

Welding on Cast Iron is also possible without doing pre-heating. This process is known as cold welding process, you can do effective weld even by skipping the pre-heating step. This process is useful when the material is big in size and it's not possible to do some pre-heating. Rest the process is the same as the above. We also have a video for you all on how to do cold welding. Check out the video on cold welding.
Here are some special techniques for you all: 1) Avoid long run during the welding, 25mm is max, after that allow the base to get cool down and again get started welding CI. 2) After every weld peen the beed - tap it lightly with the round part of a ball pen hammer. 3) Always use the specialist nickel-iron electrodes that run on low current.

Check out our new video on how to repair bench vise.

 Check our new article on Porosity and what is Phosphor Bronze.

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