How to Weld Rebar: A Comprehensive Guide

by James Anderson | Last Updated on February 17, 2023

The use of concrete has increased nowadays in the construction industry. Concrete is one of the essential materials that has mainly used for the foundation of structures. If you get any concrete project, but a question arises in your mind – how to weld rebar, right?

However, welding rebar is much more efficient as it provides more strength, better durability, and reduces the chance of cracking. Besides, it is also essential to find out the correct type of weld-able rebar to successfully carry out your construction project. This article will give you a complete discussion about rebar welding.

What Is Rebar?

Rebar has also known as reinforcement steel. Steel has used in rebar because its thermal expansion coefficient is equal to concrete. And it remarkably helps to decrease the possibility of crackling. Rebar has used to add structural strength, makes the concrete solid and robust. So it can use in various structure construction. This reinforcement steel can carry better tensile loads. It can easily withstand the stress of constructional structures.

How to Weld Rebar: A Easy Guidance

Rebar comes in various sizes and grades. But the important fact is, you cannot weld all grades of rebar. At first, you need to know the difference between rebar types that can weld and cannot weld.

You must be thinking – what will happen if you weld the inappropriate rebar in the concrete?

In case you choose the wrong grade of rebar for welding, such as high-strength or non-Grade-W rebar. The concrete will have lower tensile strength. So it may crack down or become brittle in the long run under a massive load.

If you are a novice welder and looking for complete guidance to weld rebar step by step, then continue to read this article.

Step – 1: Difference between weld-able and non-weld-able rebar

Weld-able and non-weld-able rebar are available in the store. Basically, the chemical elements and compositions of the steel make the difference between weld-able and non-weld-able rebar. You need to check the chemical composition to determine, the rebar is weld-able or not. So, you have to understand the difference.

According to the Structural Welding Code, you can weld low-alloy steel rebar because it contains a ratio of steel and carbon, which helps to weld it easily. Low-alloy steel is a suitable choice for welding and also adds strength to the concrete. Besides, once this rebar has sealed in concrete, it can stay together firmly in a massive load. Also, you can easily weld this rebar without taking many considerations.

Steel with high carbon is a little bit brittle. For this reason, it is not suitable for welding. Also, this high carbon steel can fracture when it has exposed to stress. Steel alloys contain high strength that is not perfect for welding.

Step – 2: Choose the correct type of rebar

After knowing about the difference between weld-able and non-weld-able rebar, the next step is to select the appropriate type of rebar for welding. There is numerous steel rebar available.

  • Mild Steel Bar

The mild steel bar has a plain surface and round shape. Its size may vary from 6mm to 50mm. Most of the time, the mild steel bar has used only in special projects. Basically, it has used for the construction joints in roads and runways, column spirals, expansion joints, etc. this type of bar is easy to bend, and you can cut without any damage.

  • Deformed Steel Bar

This type of bar is easy to carry and transport. A deformed steel bar gives more strength to the bond between the concrete and steel. It has comparatively greater tensile strength than a mild steel bar. Also, it lowers the cracks. There are different types of deformed steel bars available now.

Thermo-mechanically treated bar (TMT) is heat-treated, and it can deliver remarkable strength to the reinforced concrete. TMT bar has considered the best for its high-quality strength, better bending, and welding-ability.

High strength deformed bar has mainly used to reinforce concrete for its 100% welding capacity. Its low-carbon content makes it more robust and weld-able.

Step – 3: Find out the preheat temperature

Once you have selected the correct type of rebar, it is now essential to determine the preheat temperature. The importance of preheating depends on the carbon equivalent and the size. You need to find out its welding ability, and you should know the carbon equivalent of the steel.

Steel with a high carbon equivalent is mostly less weld-able. Therefore, it needs more preheating and vice-versa. For instance, the preheat temperature for rebar with a high carbon equivalent may vary from 100 to 500 degrees F.

Step – 4: Select the suitable filler.

Most of the time, the filler type you want to use for welding rebar depends on your welding process. You can use three types of welding processes to weld rebar.

  1. SMAW- Shielded Metal Arc Welding (stick/arc welding)
  2. GMAW- gas metal arc welding (MIG)
  3. FCAW- Flux Core Arc Welding

If you want to use the A615 grade 60 rebar, you can choose either the SMAW or GMAW process. In case you use the SMAW welding method, the suitable fillers are electrodes of E9016-X, E9018-X, or E9018M.

But if you go for the GMAW welding process, the appropriate filler will an electrode of ER90C-XXX or ER90S-XXX.

So, the selection of filler depends on the process of welding you want to apply.

Step – 5: Selection of right weld

You cannot use all types of welds for rebar welding. You have already known about the weld-able rebar. So, it would help if you chose the appropriate weld, metal preparation, and correct placement.

Bottom Line:

After reading the entire article, you will now know how to weld rebar and able to pick the correct type of weld-able rebar for your project work. Welding rebar has thousands of benefits. It helps to deliver a robust, firm, and structural solid bond. This strong bond not only adds strength to the structural concrete but also makes transportation easier. But you have to remember – you cannot use all welds for rebar welding.

However, many people think welding rebar is a complicated method and unacceptable by many. But the reality is, welding rebar has considered one of the best and practical ways to make sure the rebar steel can perform its purpose as efficiently as possible.

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