Welding vs. Brazing vs. Soldering: Differences Explained

When we talk about joining metals, we come across three common methods, and that are Welding, Brazing, and Soldering.

But which one should we choose?

All these methods join metals, but they differ in the working principle, temperature, and strength. They are meant for distinct applications.

Let’s dive into the details of these metal joining methods and understand how they work and where they can be used. It will help you select the right method for the job.

What is Welding?

Whenever people think about joining metals, the first thing that comes to their mind is welding. It is the most common way to join two pieces of metal.

In welding, the welding machine acts as the power source. It’s powered by electricity, and its output terminals are connected to the base metal and welding torch or electrode.

When the torch touches the base metal, an intense arc is generated because of the short circuit. An immense value of current flows through the circuit and generates a spark where the metal and torch meet.

The arc generates enough heat to melt the base metal. It increases the temperature of the working pieces instantly and goes above the melting point.

Due to high heat, a weld pool of molten metal is created. A filler material is also used to fill the gaps between the metal pieces.

The molten metal is allowed to cool down. After that, a strong weld or metallurgical bond is created joining both metal pieces.

What is Brazing?

Brazing is another method for joining metals. It is similar to welding in a few aspects but dissimilar when we look at the working principle or joining process.

In brazing, two metal pieces are joined. Before joining, the metal pieces are cleaned and flux is applied.

The purpose of applying flux is to prevent the formation of oxides and clean the surface.

Then, the pieces are heated using a brazing torch, which is usually an oxy-acetylene torch. However, there are other options like propane torches or air-fuel torches.

The temperature of the metal is increased to a level that filler material is melted easily. The filler material has a lower melting point.

Keep in mind that the base metal is not melted in brazing. The gap is filled by the filler material, and it joins both pieces together.

The torch is kept in one hand, while the filler metal is applied from the other hand.

The joints are extremely narrow, so the filler metal can fill the gaps easily.

Because of the capillary action, the filler metal covers every corner.

Finally, the metal pieces are allowed to cool down. After solidification, they are joined through a strong bond.

If needed, the residual flux and filler metal can be cleaned.

What is Soldering?

Soldering is a method of joining metal pieces using filler metal that has a very low melting point.

The purpose of soldering is to either create a joint for electrical conduction or a mechanical bond.

In soldering, a filler metal, which is also called “Solder” plays the main role.

It joins two pieces of wires or small metals together. The bond isn’t strong like in other joining processes, but it is enough to hold the joined pieces.

Solder is a soft metal that you can bend easily. It’s commonly available in the roll form like a flexible wire.

It’s made of tin-lead alloys, but now, it’s been replaced by lead-free alternatives.

The melting point of solder is quite low. It’s melted using a soldering iron.

Firstly, the pieces to be joined are placed together.

Then, the solder is applied through the hot soldering iron.

It instantly melts the solder, fills the gap, and joins the pieces together.

There is no melting or even heating of the base material. Only the solder is melted to make the joint.

Similar to brazing, it also follows the capillary action. It means when the solder is melted on the joint, it’s automatically pulled into the gaps.

Key Differences Between Welding, Brazing, and Soldering

To choose the right method for your needs, you must know the key differences.

Primary Purpose

All these metal joining methods and processes differ in their primary purposes.

The purpose of welding is to join both metals permanently. It is used to create a strong bond that can withstand immense mechanical stress and be used for heavy-duty applications.

After joining metal pieces with welding, they act like a single metal piece and can bear a heavy load.

Brazing is used for joining two pieces together and filling the gap in between.

For instance, it is used in plumbing to join two metal pieces and ensure the water does not leak from the joint.

It’s not as strong as welding and can’t bear a heavy load. However, it can join the metals.

Soldering is primarily done to create an electrical or mechanical bond.

For instance, it joints the battery terminals to a wire and ensures excellent conductivity.

It can join small and tiny metal pieces and components. It cannot bear load or pressure.

Bond Formation

In welding, the metal pieces are melted. A weld pool is created where the molecules of both metal pieces participate.

Additionally, the filler material is also added to the pool. The particles of all these elements combine with each other and create a metallurgical bond after solidification.

Brazing does not involve the fusion or melting of the base metal pieces. It mainly depends on the filler material that is melted to fill the gap.

At the molecular level, there are almost no changes in the metal pieces. Even if there are any, they are minimal and neglected.

Simply put, the filler material creates a bond and holds both metal pieces together.

In soldering, the bond is created because of the filler material. It joints the metal pieces, such as wires, quickly. The user has to put the melted solder over the pieces, and it joints them quickly.

Temperature

The major difference between welding, brazing, and soldering is the temperature required in the process.

Welding involves the melting of metals, so the temperature goes way above the melting point.

For instance, if you want to join stainless steel pieces, the temperature should be over 1540 ⁰C. Usually, the temperature in welding is around 2000-4000⁰C.

However, it can go up to 10,000⁰C in some extreme cases. Thus, the temperature in welding is extremely high.

Due to high temperature, the solidification of the weld pool takes time.

Secondly, the welder has to wait for a long time so that the joined metal pieces are safe to touch.

If the welder ends up touching the joint just after welding, it can cause severe burns.

In brazing, the temperature is also high but lower than in welding. It does not need the fusion of the base metal.

It only requires enough temperature to melt the filler material. But still, the temperature could reach 450-500⁰C.

Soldering requires the lowest temperature because it uses a filler material that has a very low melting point.

The solder can instantly melt and cool down. Once the joint is created, it solidifies in no time. The temperature is usually between 300-400⁰C.

In various aspects, soldering and brazing might feel similar. But temperature is what sets them apart.

Heat Application

For all, the method of heat application is different.

Even if we see welding, there are dozens of welding types and all of them have a different method of heating the base metal.

In arc welding, immense is generated through a short circuit. In all types of arc welding, including stick welding, TIG, and MIG, an electric arc is generated, which increases the temperature of the base metal quickly.

On the other hand, Gas welding uses a fuel to ignite the metal pieces and increase their temperature.

Laser welding is a type of welding that uses an intense laser beam to increase the temperature of the base metal. It is extremely fast, highly precise, and quite versatile.

In brazing, the metal pieces are heated using fuel. It uses a brazing torch that throws flame to increase the temperature of the base metals.

However, brazing may use a furnace, hot metal bath, and other methods to increase the temperature.

Soldering uses a soldering iron. It contains a metal tip that is heated through electrical resistance heating. There is a heating element, which is usually made of nichrome.

When electrical current passes through it, it generates immense heat, which is then conducted to the metal tip placed around the element.

Joint Strength

The joint strength of all joining methods is different, and that’s why choosing the right method is important.

You can’t join metal sheets using soldering or brazing as the suitable method is welding.

Welding offers incredible strength, and there is no competition with brazing or soldering.

It creates a metallurgical bond on the molecular level that both pieces create a single piece after joining. If done correctly, it can bear a heavy load.

Astonishingly, the joint can even be stronger than the base metal or at least equal.

If you see a stick welding electrode, you’ll notice a number. The first two digits represent the tensile strength.

If the number is E6010, the tensile strength is 60,000psi. It means the joint can bear a maximum load of this value.

Thus, the joint is extremely strong and can bear heavy mechanical stress. There are stronger electrodes as well, and they are chosen according to the base metal.

Brazing is not as strong as welding but still, it can bear some load. The filler metal melts and fills the gap in between. It holds the pieces tightly. It can bear the pressure of water or gas.

It is not a structural weld and does not affect at the molecular level. Therefore, it’s not suitable for heavy loads.

The joint made through soldering is very weak. You can even remove the joint with your fingers.

It does not need force to remove the joint. It’s just made to complete the circuit or hold delicate pieces together.

Shielding

Shielding is needed in welding, brazing, and soldering to keep the joint clean from atmospheric contaminants. However, the shielding method differs in all.

In arc welding, the shielding is provided by the flux in the electrode. It melts and produces a shielding gas to protect the weld pool.

In other welding methods like MIG and TIG, shielding gases like argon, CO2, and various mixtures are used.

In Brazing, the flux is used for shielding. It acts as the cleaner for the surface of the metal and also protects the joint from oxidation.

In furnace brazing and induction brazing, inert gases like argon and helium are used to offer shielding.

Different types of flux are used in soldering for shielding. For normal applications, it’s more than enough. However, in specialized cases, inert gases are used to minimize oxidation.

Joint Preparation

Welding requires proper cleaning before starting the process. It is necessary to minimize the porosity, uneven welds, inclusions, and other defects.

There should be no grease, rust, dirt, paint, or other contaminants. Cleaning of the joint involves grinding, wire brushing, solvent cleaning, etc. Welders need time to get the base metal ready for welding.

Keep in mind that stick welding does not require cleaning as it can be done on a rusty or dirty base metal. Other than that, all welding processes require cleaning and joint preparation.

Brazing requires moderate joint preparation. The base metal should be clean, especially the gaps so that the filler metal can flow easily.

Mechanical cleaning like grinding and wire brushing could be needed. But mostly, solvent cleaning is more than enough. Secondly, flux is applied to the surface to clean the area and prevent oxidation.

Soldering requires minimal preparation. You may need to use isopropyl alcohol to clean the surface and remove grease, oil, and other contaminants.

If there is any rust or oxidation, you can use wire wool or sandpaper to clean it. Flux is also applied to clean the area and prevent oxidation during soldering.

Post Processing

Welding requires immense post-processing.

In stick welding, there is the formation of slag on the weld beads. It’s removed through hammering. Similarly, the weld joint and the surrounding area are cleaned using a wire brush. It removes the spatter and particles around.

After cleaning, the weld beads are visible. It’s important to use a power grinder to make the joint even and leveled. It removes the excess filler material and makes the joint smooth.

Finally, a protective coating is applied to prevent corrosion on the joint as well as the base metal.

The joint made through brazing is much easier to clean. It can be washed with water or a chemical solvent to clean the surface.

It also requires minimal sanding and polishing to make it look better. A wire brush or steel wool can also be used to make the surface clean and even and remove the excess flux around.

Soldering requires minimal or almost no post-processing. If you want to clean the joint, isopropyl alcohol is more than enough for gentle cleaning.

Heat-Affected Zone

In welding, the temperature is extremely high. And due to high conductivity, the area around the joint is also affected, especially in metals like copper and aluminum.

If the temperature is not controlled precisely, the base metal could deform. Thus, the heat-affected zone (HAZ) is significant.

However, in laser welding, the heat-affected zone is minimal because of the focused laser beam. It’s the only welding process that does not put the surrounding area under heat stress.

The HAZ in brazing is lesser than welding. And it’s not a major concern as the temperature is not enough to melt the base metal. Thus, there is no need to worry about metal deformation and other issues.

In soldering, the HAZ is negligible. It’s the right choice for delicate items like electronic components. The temperature is low compared to other methods, and there is no change in the base metal.

Skill Required

Welding is a complex process, and it requires proper training. Even after training, it needs expertise and experience. Welders spend years mastering the technique to achieve perfect welds.

Firstly, proper knowledge of the welding process is needed. For that, welders go through educational and training programs.

They must understand how to operate the welding machine, safe procedures, techniques, etc. They also need to have the basic metallurgical knowledge to join base metals.

Welding requires incredible control and precision. It is necessary to control the current, speed, temperature, work angle, and a lot of things. For different types of welds, different welding techniques are used.

Brazing also requires skills and knowledge but not as deep as welding. It is less complex, and the person needs to understand only the base metals, flux, torch handling, etc.

It needs temperature control, pre-cleaning, understanding of capillary action, etc. It also requires vocational training and on-site job experience.

Soldering is the easiest of all. Almost anyone can do it after learning how to handle the soldering iron and some basics.

However, it requires practice to achieve clean and strong joints. Especially, dealing with delicate and small items is not easy.

You can do basic soldering just by watching a YouTube tutorial. But if you want to work on delicate electronic items, you need proper training.

Cost

Welding is the most expensive option. The reason behind this is expensive equipment, high skilled labor cost, safety gear, and other things. The cost of welding electrodes, inert gases, and post-processing tools, also increases the overall cost.

After welding, there comes brazing. It requires simpler and less expensive equipment. However, you have to consider the cost of the gas, filler material, and flux. The labor is also less expensive than welding.

Soldering is the least expensive option. The soldering iron, flux, and other tools, equipment, and things are quite cheap.

Advantages

Advantages of Welding

- There are dozens of welding types and processes for a wide range of metals and purposes. You can pick a suitable welding method or type, depending on the metal and application.

- The strength of the welded joint is unmatched. It is equal to the strength of the metal itself or more in some cases. It can bear heavy mechanical stress or load.

- Can join all types of materials, be it thin or thick. Even works on metal sheets.

- Welding creates permanent joints through the fusion of base metals and the filler material. It’s extremely durable and built to last for a long time.

- The applications and use cases of welding are uncountable. They are used for fabrication, repair, manufacturing, etc. In almost every industry, you’ll find an application or use case of welding.

Advantages of Soldering

- Extremely easy to learn and minimal skill is required to solder items.

- Cost-effective method of joining metals for electrical conductivity and minimal mechanical strength. The equipment is also inexpensive and easily available.

- Suitable for joining small and delicate items as it does not put the item under heat stress.

- Low temperature is required to melt the solder.

- In case of any mistakes, rework is quite easy. The solder can be removed and new solder can be applied in no time.- No need for post-processing.

Advantages of Brazing

- Offers excellent strength after joining metals. Not as great as welding, but way better than soldering.

- Ideal option for joining heat-sensitive metals as it does not increase the temperature to the melting point. The properties of the metal remain unchanged.

- Work on distinct materials. Can join different types of metal with the help of a suitable filler material.

- No thermal distortion of metals because of the minimal heat-affected zone. The joint and the surrounding area are not under heat stress.

- Less or minimal post.

-processing is needed as the joint is already clean- Much simpler method and is easier than welding.

Use Cases and Applications

Welding

Structural Construction: Welding is used in the construction industry for making structures like bridges, buildings, skyscrapers, etc. It offers enough strength to bear the heavy load of traffic and people.

Automotive: In the automotive industry, welding is used to join panels, chassis, and frames of vehicles. It makes strong and durable joints that bear the impact on roads and last forever.

Aerospace: Aircraft and spaceships require welding to join metal sheets, body components, and parts. It can join versatile metals and offer enough strength to withstand harsh conditions.

Shipbuilding: In shipbuilding, large metal sheets are joined together using welding. It helps in making the structure of the ship.

Pipeline: Pipelines are joined and repaired using welding. It’s an effective way to make strong joints that can bear the pressure of oil and water and prevent leakage.

Brazing

HVAC: Brazing can withstand high pressure and temperature. It’s preferred for HVAC applications. The copper pipes and fittings in refrigerators and ACs are joined through brazing.

Plumbing: Brazing is also a preferred option for plumbing for its durability. It’s used to join copper pipes. It withstands water pressure, prevents leakage, and lasts for a long time.

Automotive: In automobiles, brazing is used to join dissimilar metals and copper. It’s preferred for AC pipes, radiators, heat exchangers, etc.

Aerospace: Spacecrafts need strong joints and dissimilar and delicate materials where welding can’t work. Brazing is the best option as it does not affect the base metal.

Soldering

Electrical Connections: Wires, batteries, connectors, and other electrical connections are made using soldering. It ensures excellent conductivity and holds the connection firmly.

Electronic Components: Electronic components are soldered to the PCB board. It’s the only way to provide electrical conductivity without damaging delicate components.

Jewelry: Delite jewelry items can be joined through soldering. It’s a cost-effective option for repairs.

Plumbing: Soldering is also used to join copper pipes. It’s an easy method and can bear water pressure. However, not as good as brazing.

Conclusion

Welding, Brazing, and Soldering are the three important methods for joining metals. A soldering iron can’t be used for joining metal sheets, and welding can’t be used for joining electronic components.

All three methods are meant for different purposes and applications, and it’s important to choose the right one for the right purpose.

We have explained the differences between them in detail to help understand the role of each metal joining method and select the right one for your needs.