Can broken cast iron be repaired?

Cast iron is most profound in industrial and household structures. This is a durable metal that can be used for decades. However, it can develop a crack due to its wear and tear. The cast iron may also be damaged if it accidentally falls. Whatever the reason is, we know that repairing cast iron is what comes into mind first.

It is possible to repair cast iron. However, it may also affect the current state of the metal. Cast iron may contain additional elements that can be difficult to weld. When it absorbs heat, it can result in expansion or contraction, which may lead to cracked parts.

To know how you can repair the cracks in a cast iron, read through the methods listed in this article.

What Exactly is a Cast Iron?

This metal is a type of iron alloy that is made mainly of iron. It also contains 2% or 4% of carbon.

Compared to other types of steel, cast iron is more fragile and soft. It is also prone to rust, especially when exposed to water frequently. Due to this, any product that is made of cast iron should be handled with care.

What causes cast iron to crack?

Cast iron pans crack when there are sudden temperature changes. The application of warm water on cold plates may lead to cracking. The surface may crack easily when you take a piece of cast iron.

Cast iron has a brittle property. Therefore, it is prone to crack easily. For example, a cast iron that is run with cold water, even if it just went off from the stove, may crack. The same goes when you suddenly pour boiling water into cold cast iron.

It is advised that you allow your pan to cool for a while before cleaning it. Or, you may use hot water in rinsing.

If you think it can still be used, small rips are fine, but only if they are inside a saucepan. Typically, it is better simply to replace your iron skillet.

How to Repair Cast Iron

Cast iron was often used by various industries and households. Cast iron objects will last for years if maintained properly. Occasionally, it will fall or develop cracks because of rust. Further damage will happen if the crack is not repaired.

Whatever the damage is, fixing the broken pieces should be done immediately. These processes are not recommended for repairing a cast iron skillet.

Casting companies are specialized in repairing the cast iron part. They can fix a crack in a metal that has a thickness of up to 1 foot. They have the right tools, equipment, and other types of materials that can be used in repairing broken pieces.

Repair by Cold Metal Stitching

The cold stitching process is done for metal that is damaged with cracks. It is a popular method to join a part of a broken part using metal keys. It is suggested that you bring the cast iron to casting companies since they are more skilled in repairing this kind of metal.

Cold metal stitching is started by drilling holes along the cracked surface. It is best that more holes are drilled on the crack than on either end.

The next step is to connect the cracked cast iron pieces through the holes. The metal keys are the most important material in cold stitching since it strengthens the repaired metal and prevents the cracks from recurring on the surface.

The metal keys will not hold enough of the pieces, especially under an extremely hot temperature. It needs to get sewn by applying screws between the metal keys. The screws should be tight since they will hold the bond of the metals.

Once the cold stitching is done, you need to finish the repair by removing the excess materials from the metal keys and screws.

Repair Cast Iron with Epoxy Putty

Cast iron part cracks can be fixed using epoxy putty. Different brands can be bought from the market, but the most commonly used are JB Weld or Quick Steel. The epoxy will serve as a glue and fill in the cracks of the cast iron.

Before applying the epoxy, sand the surface of the cast iron to remove rust and other substances that cover the cracks. It is recommended to sand in back and forth motion o avoid worsening the crack. Wash the cast iron surface with soap and water and allow it to dry.

Make the epoxy mixture based on the instructions as seen on the packaging. Use the epoxy mixture to repair the cracks. Make sure to fill in all the rest of the spaces with epoxy. The excess glue should be removed from the surface before it gets hard.

To finalize the repair, paint over the sealed cracks for durability. pair cast iron with brazing

Welding Cast Iron

If doing it in-house, ensure that the welding rod to be used is appropriate for the cast iron. The most commonly used welding rod for this type of metal is the ferronickel. Using a pure nickel will create a softer weld deposit.

The welding method requires appropriate pre-heating since cast irons are prone to cracking if the metal reaches its weld stress point. The cooling process of the welded parts should also be controlled by using insulating materials.

Fix The Broken Cast Iron Part Through the Brazing Process

Since cast iron easily cracks, another method that can be done for repair is through brazing. This is also a type of welding, but unlike the typical one, the process is more recommended.

People who are skilled enough and have the right tools for a brazing process can do this DIY. The filler rod used for repair depends on the cast iron part. Some casting companies use filler rods that are made from nickel or flux.

If doing this DIY, the surface should be thoroughly cleaned by a grinder. Grind out the surface to form a U-shaped cross-section. This method prevents stress concentrations and allows the brazing material to fill the spaces fully.

Brush the ground area to remove dirt and particles from grinding. Heating the cast iron part using a brazing torch, oven, or anything that can heat the cast iron can be used. During this process, the joining parts should be heated with a brazing torch to let the rod flow onto the surface effectively.

Once done, place the cast iron in a container with sand and cover it to let it cool down for up to one day.

Castaloy Cast Iron Repair Kit for Broken Cast Iron Pieces

For a cracked cast iron skillet, using this cast iron repair kit is more recommended than the two options of welding.

To fix a cast iron skillet, it needs to be cleaned with a wire brush or steel wool to remove dirt and excess food debris. No need to worry about the seasoning since it can be done once the cast iron skillet has been repaired.

Apply the Castaloy rod to the skillet by using use a propane torch to heat and liquefy the rod. Tilt the pan to fill in the cracked area. Once done, let the Castaloy cool down, sand the excess product, and season the cast iron skillet.

This method will not work for reattaching parts. It is better to replace the pan or bring it to a welding service shop.

Rust on Cast Iron

In general, rust is a usual issue for a metal.

The most common causes of rust on cast irons are exposure to moisture or if it is submerged in water for a long period and has dried naturally.

To remove rust from cast iron, use a 1:4 solution of vinegar and water. Then soak it for 1-2 days to remove tough rust. This removes all seasoning, and you may slowly heat the cast iron after you clean it up.

For severe rust that covers most of the cast iron surface, you can take it to a machine shop and have it sandblasted. It will be restored to raw cast iron, then season immediately.

Frequently Asked Questions

Can a hole in a cast iron be repaired?

Yes. The holes in a cast iron can be filled either using cast iron filler material or epoxy putty.

How do you repair a cast iron?

If it does not require welding, it can be fixed by brazing, epoxy putty, or cold metal stitching.

Can you fix a detached handle from a cast iron skillet?

Though it can be welded, replacing the cast iron pan is the best way.

Final Words

Cast iron can be fixed with different methods depending on its type. Fixing the small damages immediately on the cast iron is important. It will prevent further damage, no matter what caused it.

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