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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.
Steps
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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.
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Preheat the sections that require work to the 500 to 1,200 °F (260 to 649 °C) range (260 to 649 Celsius). [1] X Research sourceAdvertisement
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Keep nearby iron cool, but not cold. If cold, you can sometimes run the machinery to get it up to the desired temperature.
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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.
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Repair cracks and rips by attaching a cast part that serves as a patch between intact parts of the cast iron. [2] X Research source
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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. [3] X Research source
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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. [4] X Research source
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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.
- To stay safe while welding, protect yourself from UV radiation. Welding produces intense ultraviolet (UV) radiation, which can harm your eyes and skin. Ensure to shield nearby people and use screens or curtains to confine the welding area.
- Regularly check your welding equipment for damage or defects. Faulty equipment can pose safety risks, so it's crucial to maintain it properly.
- Be cautious of electrical hazards. Welding involves high electrical currents, so ensure you have a properly grounded workpiece and avoid contact with the electrode, work clamp, or any other live electrical parts.
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Community Q&A
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QuestionWelding cast iron, do I use ac or dc welder? I have welded cast but it has been close to 40 years and two brain stem strokes, so I do not remember.Community AnswerUse high nickel content welding rods. The proper polarity will be specified on the box.
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QuestionCan metal be heated before it's welded?Community AnswerYes. Sometimes it helps to heat it before it's welded, depending on the type of metal. Also, keep in mind, your metal will heat as you weld. The heat from your welding will travel through the metal, making it hot.
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QuestionI need to repair a cracked 50 mm cast iron body machine. Should I use low hydrogen or high nickle?Community AnswerGo with a nickel rod if you’re arc welding. You can also get away with brazing cast iron with excellent results. You may wish to use additional pieces of carbon steel flatstock to increase the holding strength; it will help distribute the loads exerted to the area of repair. If the casting breakage is not a result of an anomaly (poor original quality, machine “crash,” physically dropped), the original casting may be insufficient in strength to bear the current mechanical load(s) imposed by the machinery, in which case, if no supplements are added (regardless of the achievement of an excellent repair joint), you may find it necessary to have at it again at some point down the road.
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Tips
- Cast iron is typically higher in carbon than steel. This makes the iron brittle, and more difficult to weld than other industrial metals. [5] X Research sourceThanks
- 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.Thanks
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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.Thanks
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Things You'll Need
- Welding rig
- Safety goggles
- Cast iron patches
- Welding gloves
- Welding apron or work suit
Expert Interview
Thanks for reading our article! If you’d like to learn more about welding, check out our in-depth interview with Jones Welding & Industrial Supply Company .
References
- ↑ https://www.esabna.com/euweb/oxy_handbook/589oxy15_5.htm
- ↑ https://makeitfrommetal.com/how-to-weld-cast-iron-uncatastrophically/
- ↑ http://www.weldingtipsandtricks.com/welding-cast-iron.html
- ↑ http://weldguru.com/OLDSITE/CastIron.html
- ↑ https://www.brazing.com/Support/Procedures_and_techniques/CastIronWeldingProcedures.aspx
- http://www.weldingtipsandtricks.com/welding-cast-iron.html
About This Article
Article Summary
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To weld cast iron, start by preheating the section you’ll be working to a temperature between 500 to 1200 degrees F so that it’s stable enough to work with. Then, fix any cracks or rips in the surface by using a small piece of iron as a repair patch. Weld the repair patch in place using short welds, about 1 inch long, to keep the nearby metal from overheating. Afterwards, seal off any small cracks in the joints with sealing compound to create a watertight surface. For more advice, including how to tell when you should reheat or cool the iron as you work, keep reading.
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