The process of welding hardened steel to mild steel requires a level of expertise and care not required for other materials. The combination of these two metals, along with the need for additional support, may make it challenging to weld a steel-to-steel connection. Welding hardened steel to mild steel is even more challenging. The different properties of each metal and the tendency for them to expand when heated can make this connection a headache.
Before you dive in and attempt to weld hard steel to mild steel, you will want to be prepared with the right information. Keep reading if you want the details on how this connection works and what you need to know before attempting this welding project.
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What is welding hardened steel to mild steel?
This process is performed using an argon or similar shielding gas with a low or medium pressure, around 2,700-5,700 psi. The process is used to join or weld hardened steel to mild steel. Hardened steel is the name given to steel that has been hardened by heat treatment. An alloy is created by combining chromium and carbon. Melted steel is what is used to weld with. This is not to be confused with high-strength steel, which is used in structural applications and made of more advanced alloys.
The process of welding hardened steel to mild steel is accomplished by using a special weld seam that has a special composition to make the weld more forgiving. This composition can be adjusted to weld other types of metals.
Options for weld hardened metal
The first step in the welding project is to decide which type of welding to perform. Rolling arc, gas tungsten arc, mig or submerged arc? The choice depends on the type of construction, existing conditions and other factors. If you choose a gas tungsten arc welder, you can also choose between MIG welder or flux cored arc welding. The main difference between the MIG and flux core welding is the welding speed of each machine. The next step is to decide on the type of steel to weld. There are three basic types of steel: carbon, low alloy and high alloy. Consider the type of steel you want to weld. For example, if you are welding steel pipe, you should choose a low alloy steel to avoid possible problems with chloride- or salt-based materials. The same would apply to steel cables; choose one without a lot of zinc.
Required equipment for welding steel-to-steel
Arc welding helmet, goggles and gloves – These are a must for any welders. Make sure to wear them when welding because a burn is much more dangerous than a simple scrape.
Shielded metal or ceramic electrodes – These are the source of the heat in welding. They are made of high purity material and coated in an oxide to protect the material from oxidation. They are also commonly known as “arc suppressors.”
MIG or stick welder – This type of welding machine can weld mild steel to mild steel and also weld a variety of other types of materials.
Wire feeder and tubing – These are used to feed the material through the welding machine.
How to weld hardened steel to mild steel
Now that you have completed the equipment and material selection, it’s time to get down to the welding basics. Start by setting up your welding machine and checking the material thickness. This will ensure that the machine is set up correctly for the welding project. Then, preheat the joint with the electrodes. This is done to relieve the metal of its own internal stresses and to increase the metal’s ductility so that the weld can be easily broken. Preheating also helps the weld to form a better bond to the joint.
After preheating, you can begin feeding the welding wire and material into the welding machine. Feed the material smoothly because it will have to travel through the machine’s arc and heat up several times. Now that the welding process has started, keep an eye on the joint and make any adjustments as needed.
Thicknesses of welding hardened steel to mild steel
The thickness of the metal can make welding more difficult or easy, depending on the thickness of the metal. The following is a list of commonly welded metals and the thickness of the metal they can be welded to. – Mild Steel – 3/32” minimum, but usually between 3/16 and 1/2” – Mild Steel with 1/2” Thicknesses – Not recommended – Alloy Steel, Carbon Steel and High Strength Steel – 1/8” minimum – Stainless Steel – 3/16” minimum
Pros and cons of welding hardened steel to mild steel
Pros – – – – – – –
| Pros | Cons |
| The welded joints are stronger than the original metal. | The welding process is a great challenge |
| The welded connections are more resistant to fatigue and impact. | The welding project is more challenging than welding mild steel to mild steel. |
| The welding project is easier to complete because it does not require high-pressure equipment. | The welded joints are more difficult to inspect than mild steel-to-steel welds. |
| The welding process is less hazardous. | The welded joints are more likely to fracture than mild steel-to-steel welds. |
| It is less expensive than high-strength welding. | It is more difficult to weld hardened steel to other types of steel. |
| The joint is less likely to leak because it is not made of high-strength steel. | The welded joints are more likely to crack than mild steel-to-steel welds. |
| The welded joints are lighter than the originals. | The joint is more likely to leak than mild steel-to-steel welds. |
Safety precautions when welding steel to steel
When welding any material, the most important rule is to follow the manufacturer’s instructions and the rules of the welding code. When welding steel to steel, follow the AWS Welding Code, AWS D1.1. Another important safety rule is to work in a ventilated area with proper personal respirators. Also, wear eye protection and clothing that is resistant to heat and flame.
Tips and warnings for welding hardened steel to mild steel
- Preheat the joint.
- Feed the welding material through the machine slowly, keeping an eye on the joint.
- Weld in a controlled manner.
- Inspect the joint after the welding job.
- Clean the welded joint with water.
- Do not use the joint.
- Do not weld more than one joint at a time.
Final Thoughts
Welding hardened steel to mild steel can be challenging because of the different properties of the two types of steel. However, by following the instructions and rules of the welding code, the challenge can be overcome. One thing is certain, you will have a successful welding project.