Differences Between Welding and Brazing

Welding and brazing are two common ways of joining metal pieces. These metal joining methods are not uncommon and usually used as a quick solution to join a pipe, connect metal bodies, fix metal joints and build metal structures.

There are many differences between welding brazing and each method is suitable for specific needs. In addition to this, there is also soldering, which is another method to join two base metals.

With so many ways to join metal, it is important to learn the differences between welding and brazing, as these are the most common metal joining methods. We will also cover brazing and soldering in this guide.

By: Tuling Engineering Team —6 minute read

Tuling Metal is a fabrication company with expertise in welding brazing and soldering methods used for joining large assemblies.

What Is The Brazing Process?

Brazing is a method of joining two dissimilar metals together. In braze welding, brazing alloy filler metals are used when joining dissimilar metals.

Brazed joints do not melt the base metals. So how does brazing join metal pieces? In the brazing process, the two metals being joined form a bond with the filler metals which come from brazing rods.

Brazing rods are sticks of brazing alloy metals that melt at significantly lower temperatures than the base metals and allow material flow between the gap in the two metal pieces to form metallurgical bonds.

In braze welding, the two base metals never make contact and the bond is held together by the filler metal.

Importance of Capillary Action In Brazing

Brazing metal joints works by a capillary action. In brazed joints the capillary action draws the molten filler metal into the joint between the two metal parts. Capillarity is the ability of any liquid to flow into pores without any pressure.

For brazing to be effective, the two metals should be close together, so the liquid, in this case filler, can flow between the tiny spaces.

How Does Brazing Work?

The Brazing process is very simple and repetitive.

Removing Oxide layer: First, the naturally formed oxide layer on your copper, iron, or steel is removed using a wire brush.
Brazing Rod: Select a braze rod that can join metals. This depends on the material of the base metals and your choice for flux or flux free rods.
Heat the two metals using a fuel torch or gas welding torch.
Melt the braze rod just around the gap and let capillary action flow the filler metal into the joint.
Allow it to cool naturally.

What Is The Welding Process?

Welding joins metals by heating the base metals above their melting point which fuses them and filler materials are used as binders during welding.

Different welding processes exist but generally, welding involves the application of concentrated heat to the bare metal in order to melt it and the filler rod. Unlike brazing, welding does not rely on pore filling. Welding is usually done on gaps much larger than those suitable for brazing joints.

Welding also requires the metal pieces to be thick enough to undergo such high temperatures without ruining the shape of the workpiece.

Different types of weld joints require different spacing of the metal for complete fusion. Generally, a 1.5 mm gap is ample for welding filler metal to flow.

Similarities between Welding and Brazing

Both welding and brazing are used to join dissimilar metals. Even though welding is different from brazing, there are many similarities between the two processes.

Welding and brazing both require filler material for metal surfaces to form metallurgical bond. They are both suitable for joining most metals like copper, steel, brass, and iron.

Both weld joint and brazed joint show seams or weld marks. Welding and brazing both are used for permanent assembly and both require localized heat. Localized heat application involves only heating a certain portion of the two pieces, in this case, the place where a braze or weld is going to form.

Brazing and welding have similar part preparation and cleaning techniques. Most welding techniques or welding operators can also perform soldering and brazing.

Difference between Welding Brazing

The main difference between welding and brazing is that brazing uses a much lower melting temperature than welding. In welding, the base metal needs to be melted for fusion which requires intense heat and temperatures above 800 °C.

In brazing, there’s a capillary action of the filler materials joining dissimilar metals, whereas in welding there’s melting of base metal to form a weld pool.

Here are detailed differences in welding and brazing:

Gap Size

Brazing requires as minimal as possible of a gap size because the filler metal has to flow into the pores through a suction technique (capillary). In welded joints filler metal can penetrate through the gap and fuse with the metal in gaps as large as 6 mm.

Brazing is great for narrow gaps and thicknesses. Brazing does not require high temperature so there is a smaller chance of distorting thin metal sheets, narrow pipes or deformation due to intense heat

Joint Type

Many welding techniques are suitable for different kinds of joints and shapes. For example, arc welding can be used for thick sheets without heating the entire workpiece.

For most shapes and joints like butt joint, lap joint, and tee joint, welding can easily bond the metal pieces. However, brazing can perform the same function without expensive welding techniques.

Braze joint takes less time and effort when compared to welding linear joints. Brazing allows the filler material to follow the line and flow into the gap, while welding requires precise positioning and tracing of the line using a tungsten electrode.

Material

Welding process requires heating the base metal for this reason welding is mostly used to join similar metals at least of the same melting point. Unlike welding, brazing can join different metals with separate melting points such as copper and steel.

It is possible to join different metals using welding as well but it’s not a common practice.

Advantages of Welding

There are many reasons welded joints are preferred over brazed joint. For starters, they are stronger and longer lasting. Here are the key advantages of welding

Arc welding or mig welding can work with most metals
The welded joint is almost as strong as the real metal
Welding can be performed in the atmosphere, underwater, or in the presence of other gases
Welding is useful when many welds have to be made
Joining metal using welding works on thicker materials
It is possible to get a better finish by welding
Automated robots mostly do welding in factories.

Disadvantages of Welding

Welding is not the safest method of joining metals
Welding small joints can be expensive
Joining metals of thin gaps is not ideal for welding
Mechanical properties of the base metals can alter
There are heat-affected zones caused by the intense heat that involve melting base metals
It gets difficult to weld aluminum with steel or join dissimilar metals
Stronger joints

Advantages of Brazing

Brazed joint can be formed using lower temperatures
Mechanical properties are not altered
Base metals are not melted
Thin pieces can be joined
Relatively lower costs
Joins same base metals more cost-effectively than welding

Disadvantages of Brazing

Brazing is not ideal for joining metals of different compositions
Joints are relatively low in strength
Brazed joints tend to fail in high temperature working conditions
Strength of joint depends on capillary action
It is not ideal for assemblies with many joints
It requires close gaps or tolerances

Applications of Welding

Welded joint is strong, robust, and can be done on-site. There are many industries which benefit from welding. Key applications of welding are

Pipes: Welding is crucial for pipelines that transport oil, gas, and fluids. A welded joint is leakproof.
Structural assemblies: welding is done on large structural assemblies like bridges and trusses to bond the metals together.
Automotive industry: Welding permanent joints is commonly used in car manufacturing to weld car pillars to the chassis.
Aircraft: Aircraft and defense industries rely on welding to join components like wings.

Brazing Applications

Brazing is used in HVAC systems because the temperatures are low and it is ideal to weld copper using brazing.
Radiators: Brazed joints are used to connect car radiators.
Electronics: In electrical circuits, brazing is commonly used to join connectors
Jewelry: Brazing can join precious metals like gold and silver without thermal distortion and deforming distinct features like designs and delicate ornaments.

How To Choose A Filler Rod?

Whether you decide to do brazing or welding, you will need to find a filler rod or electrode that suits your weld. To choose a filler rod there are just a few key considerations

Base Metal: When selecting filler material it is important to understand the characteristics of the base metals. You need an a filler alloy that matches the melting point, tensile strength and hardness of your base metal.
Inert Gases: Inert gases can help keep metal from reacting with oxygen and forming an oxide on the surface. Some gases can help you deposit more filler material to the weld spot.
Size and Amperage: Different-sized electrodes can run different amperage or current in TIG Welding. The larger the diameter the higher the amperage needed.

How Can You Decide Between Brazing or Welding?

For most applications welding almost always works. Whether it’s repairing pipe leaks, joining large structures or simply aiming for a permanent join between metals. Brazing offers an alternative to welding which is cheaper, requires less energy, and is easier to perform than welding.

Brazing is usually used in places where small stress or load is expected on the joint. You can use brazing where the operating temperature is not expected to exceed the filler materials melting point. For example, repairing water pipes.

Welding can be used almost anywhere but requires special technique and skill. Welding is used in metal structures like bridges, staircases, car bodies and underwater pipes. It can sustain higher temperatures and better loads.

Conclusion

Both welding and brazing are used for permanent joints. Brazing two metals does not require a lot of skill because the filler material draws into the pores and gaps. Welding is a skilled job and is much more likely to be used for commercial applications.

Choosing between welding and brazing it depends on the base metals being joined, the type of joint, how many welds or brazes are intended, and the thickness of the material.

Tuling Welding and Brazing Expertise

You can reach out to our experts about your products and have instant advice on your unique welding or brazing project. Tuling is a metal fabricator and product manufacturer with state-of-the-art welding and brazing centers.

We also perform ultrasonic testing to find any incomplete welds or cracks before finalizing your project. Our welding centers offer unmatched quality checks and modern equipment.