Fixing Cast iron without welding before and after

How to Fix Cast Iron without Welding?

Iron comes to us in many different shapes and forms.  Among those forms is Cast iron, which usually takes more than 2% carbon alloys; if the carbon alloys are less than cast iron’s carbon alloys, it would be called steel.

It cannot be molded not by a huge effort but by casting (pouring into a mold after heating), and that’s why it is more likely to crack or rust because of its liable hardness.  It gets cracked for several reasons, one being extreme temperature swings.

The railway lines were made up of cast iron in the old days, even today, that’s why in hot summers, these railway tracks get loosened a bit more than their actual size, and in winters, they get shrunk.

Welding cast iron is not a piece of cake. You need mastery over holding and using MIG or gas welding guns. In the following, a few methods can be used as a substitute for welding cast-iron pieces.
These ways are less prone to danger as well as quicker and safer than welding. These three methods are brazing, epoxy putty, and cold metal bonding.

After this short intro on how to fix cast iron without welding, let’s move on to fix it.

Read Also: Fix Cast Iron to Steel 

How to Fix a Cast Iron without Welding?

The three commonly used methods to repair cast iron without welding it are:

  1. Brazing
  2. Cold Bonding
  3. Epoxy Putty

Read the blog to the bottom to learn about these procedures in detail.

1: Repairing Cracked Cast Iron Using Brazing

Brazing is another way of fixing cast-iron surfaces. In brazing, you need an extremely high-temperature brazing rod. This method is to fix two uneven surfaces that might have been broken due to pressure.

Brazing Cracked Cast Iron :(A Step-by-Step Repair Guideline)

Brazing process graphical illustration
Image Credit: Newkidscar

1: You need to select a filler rod depending on the application of the cast iron part. Filler bars made of nickel or brass are most commonly used in cast iron brazing. Make sure to select the metal that offers great strength.

2: Once you have chosen the filler bar, you need to clean the crack surface on the cast iron to remove any layers of impurities and oxides. Now you need to use a grinder to create a cross-section in the crack where the filler bar would sit. This will help the melted filler bar to flow fully into the crack.

grinding the cracked iron piece

3: Use stainless steel to clean the ground area of the cast iron piece to remove any residue left after grinding.

cracked cast iron piece after grinding

4: Apply heat to the cast iron piece. Remember, using a brazing torch causes more cracking and warping on the cooler parts of cast iron because of the heat intensity, so we recommend you use a technique such as an oven, gas grill, or a weed burner to heat the cast iron part slowly.

5: Time to insert the melted filler metal into the crack. Make sure to maintain the optimum temperature around the crack before filling the metal, and We recommend you use external heating sources to concentrate heat around the crack.

Inserting filler metal into cracked cast iron

6: Finally, the piece is repaired. Now you need to cool it down very slowly. For that, the most common method is to place the repaired piece in a container full of sand. We recommend you to let be there for at least a day or two. Remember, after the brazing procedure, don’t let the cast iron piece sit in the air to cool down, as it may crack.

cracked iron piece after brazing

2: Repairing Cracked Cast Iron Using Epoxy Putty

Epoxy putty is a glue-like but a bit hard material. It is used to fix cast-iron cracks but is temporarily fixed until a permanent solution is taken up. At room temperature, this epoxy putty adhesive substance is used for space-filling.

Use of Epoxy Putty for Cracked Cast Iron :(A Step-by-Step Repair Guideline)

  • First, you will need to buy epoxy putties. You will easily find them in any local hardware store. We prefer to use JB weld or quick steel. These come in two tubes and serve as glue to fill the crack.
  • Clean the cast iron surface with 80-grit sandpaper to remove any impurities from the surface. This process will also make the surface rough to bond the glue with the surface strongly. Remember to use back-and-forth movements for cleaning surfaces instead of circular movements to prevent the crack from widening.
  • Clean the surface area with soap, water, and a rag to remove any particular sandpapering. Before moving further, let the cast iron area dry completely.
  • Squeeze the putty out of the tube on some surface, such as cardboard, and mix it using a knife. Find the manufacturer’s instructions on how to mix it printed on the packing.
  • Apply the putty to the cracked surface with the knife. Make sure to fill the crack completely with the putty. Scrap off any excess putty before it gets hard to remove it easily. We recommend you not handle the cast iron piece before 24-hours after putty application.
  • Ensure to paint over the sealed crack piece where you filled the putty. This makes the repaired cracked part match the rest of the cast iron piece and enhances its durability.

Repair Cast Iron with JB Weld (Epoxy Putty)

3: Repairing Cracked Cast Iron Using Cold Metal Stitching (With Pictures)

A method that we can use to repair cracked metal that can’t be repaired using traditional procedures, like welding. This process involves lacing up the crack metal using any other metal. You can use this method to repair aluminum, cast steel, and cast iron.

Cold metal stitching’s popularity is increasing with every passing day because of its ability to repair any structures that are not easy to disassemble or replace. Construction workers around the world use this technique to preserve old buildings.

Shipping companies worldwide use this method to repair old booked engines rather than replace the old ones with new ones. The method is well-known in mining, transportation, construction, heavy-engines machinery, construction, and many other areas.

Let’s follow a step-by-step procedure for using cold metal stitching to repair cast iron.

1. Metal Crack Diagnosis

First, you need to look at the crack you will repair. This method lets you ideally repair the cracks with a thickness of 3/16 inches up to a foot. You can ignore the length of the crack, as it does not matter. The nature of the crack decides whether it can be repaired or another cast iron piece needs to be created.

2. Drilling Holes Along the Crack

Now place the holes on the crack at a specified distance. We recommend using a guide to place holes along the crack accurately. It’s unnecessary to have the same number of hole sets. There could have been more holes on one side and a few on another. The goal is to create stitching points strong enough to bond the cracked iron.

3. Connecting Hole Rows

Once the holes are drilled, now you need to connect them. This will make it easier to insert the metal stitches, strengthening the cracked cast iron. You must connect the holes using a large chisel without creating space in the metal.

Once you insert the metal key, the rounded shoulders achieved through drilling will act as the holding points. Maintaining the outer diameter of the drilled holes while connecting them is very important.

4. Insertion of Metal Keys or Stitching

Metal keys are the most vital element of the procedure. Because they provide the strength required to keep the repaired metal together. Make sure to use the metal that offers extended strength, or you will have to repeat the process.

The length of the metals must be the same as of the holes you drilled in the first place. This will add strength to the whole surface area and prevent further cracking. Make sure to keep them tight to create a solid bond; there should be a little gap between the original piece and the metal stitch. You will require a mallet to press fit the stitch in.

You should worry about the extra material from the original part surface. It can be easily dealt with in the finishing process.

5. Sewing the Metal Stitches

Joining the cracked cast iron piece only with metal stitched is not enough. Because these metal stitches may break upon putting heat and intensity on the cast iron piece. So, you need to nail in the screws between the metal stitches.

Neighboring screws and metal stitching keys should be close to each other. Tightening the stitches will create a robust bond between the repaired metal and the cracked cast iron.

Just as with the metal keys, it’s okay if there is an extra metal that may be sticking up from the screws that have been installed. The excess material will come in handy when finishing the surface, and it will appear as one whole cast iron piece.

Lining up the flush with the original cast iron piece’s surface will help eliminate weak spots and the reoccurring crack chances.

6. The Finishing Steps

The final step involves chiseling away the extra material from the metal stitches and the stitching screws. You need to remove the metal material as much as using the chisel. The rest will be done using the grinding tool. The finishing process is vital in restoring the cast iron to its initial position. Use the excess metal to hide the repair work for a cleaner outlook.

Cold metal stitching step by step process


If your cast-iron pieces, like pans, etc., are rusting, you may try seasoning. It includes the following procedure:

Wash the cast-iron for once with 50/50 water and vinegar solution. Keep it in the solution for half an hour. Oil it a bit, and unrefined oils are much better.  Now start seasoning, apply thick oil coding on the pan, wipe it with toilet paper, and put it in the oven for 5 minutes at 200 degrees centigrade. If you want good seasoning, repeat this process 5 to 6 times. This will lead you to a fine cast-iron piece, free of rust and cracks.

How to Prepare Cast Iron Piece Before You Start Repairing It

If you are looking to buy a new cast iron piece, it could cost you extra bucks, so repairing it is a good option. You need to clean the cast iron piece to remove any residue, regardless of which method you opt for.

Following the guidelines below will help you efficiently clean cast iron pieces before repairing them.

Cracking is not the only problem with cast iron items; they might also get rusty or burnt. First, you must sprinkle salt on its surface if it’s burnt. Afterward, use a steel brush or scrub to clean the surface. Using a damp brush could clean it more efficiently. However, if the burn is difficult to eliminate, the plastic scraper can come in handy.

On the other hand, if the cast iron piece has rust, using a scrub or detergent can help to get rid of it. Eliminating rust timely could prevent cast iron from further damage.

You can restore the color of your cracked cast iron piece by scrubbing it with steel wool. First, you need to scrub it to remove dirt traces from it. Then wash it with soap and warm and let it dry to restore its color.

Once the piece is dry and clean, you need to eliminate defects like porosity with a grinder that will make the surface ready to repair.

Seasoning of a Cracked Cast Iron

If your cast-iron pieces, like pans, etc., are rusting, you may try seasoning. It includes the following procedure:

Wash the cast-iron for once with 50/50 water and vinegar solution. Keep it in the solution for half an hour. Oil it a bit, and unrefined oils are much better.  Now start seasoning, apply thick oil coding on the pan, wipe it with toilet paper, and put it in the oven for 5 minutes at 200 degrees centigrade. If you want good seasoning, repeat this process 5 to 6 times. This will lead you to a fine cast-iron piece, free of rust and cracks.


1: Can JB Glue Join Cracked Cast Iron Pieces?
Yes, JB can be used to repair cast iron. It acts as glue by sticking to cast iron that successfully fills and seals the fracture.


Ultimately, it can be understood that cracked cast iron can be fixed without unlevelled welding. It is a difficult task and risky as the temperature exceeds a safe limit that may cause burning. So, you should move to the safer ideas rather than opting for welding to fix your cast iron-made things such as water pumps, pans, drums, etc. These ideas aim only to produce pieces of showroom quality that could be pleased having been in the gallery, home, or office.

If you don’t want to use welding for bonding metals, read our other how-to guides:

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