Is Aluminum Brazing as Strong as Welding?

Is Aluminum Brazing as Strong as Welding?
December 5, 2022

Is aluminum brazing stronger than welding? It’s a question asked by engineers and others in the military and aerospace industries.

When joining metals, welding and brazing are both viable options. But, it can be complicated and confusing when choosing the best method for the task.

We will explore the distinctions to gain a better understanding of metal joining. Read on to learn what you need to know and help you choose the optimal method for your job.

How Does Brazing Work?

If you compare brazing and welding, you will realize that the procedures are very different. In brazing, the metals are not melted. As a result, brazing temperatures are lower than the melting points of the metals, whereas welding temperatures are higher than the melting points of the metals.

It requires less energy to produce a brazed joint when compared to a welded joint. To create a brazed joint the filler metal is brought in contact with the heated parts, instantly melting as a result of the heat, and drawn through the joint by capillary action. 

Rather than melting base metals together to make a joint, in aluminum brazing, it’s a lot easier to solder dissimilar metals using a flux or flux-cored or coated alloy. Flux or flux-cored or coated alloys are simple to use to join dissimilar metals.

It doesn’t matter if base metals have varied melting temperatures if you don’t have to melt them. You can join steel to copper with the same ease as steel to steel. But, if you attempt to weld copper to steel, you must use advanced and costly welding techniques.

It is simple to combine various metals using conventional brazing processes, knowing that you won’t have any issues joining them no matter how much they differ in melting temperatures. Brazing has common use in various industries, including HVAC/R, electronics, aerospace, automotive, construction, and more.

Air conditioning systems for automobiles, jet turbine blades, satellites, and fine jewelry are all examples of aluminum products where brazing takes place. Because of its ability to bond dissimilar base metals, brazing is beneficial in a variety of applications. 

Types of Brazing 

You can use different heat sources during brazing. To meet brazing temperatures, some procedures heat the joint region using local heating.

Other methods will heat the entire assembly. This method refers to diffuse heating.

Torch Brazing 

Torch brazing is a method in which filler metal is melted and flowed using a fuel gas flame combined with oxygen or air. You can automate this process and it requires a low capital outlay.

Fuel gasses such as acetylene, hydrogen, or propane can combine with oxygen or air to produce a flame. Post-brazing cleanups are often necessary because of the need for flux. 

Induction Brazing 

The process of brazing using high-frequency induction heating is clean and quick, allowing for precise temperature and location control. An adjacent coil induces an alternating current into the workpiece, generating heat. 

Resistance Brazing 

An electric current flowing through a circuit, including the workpieces, generates heat in this process (for example, induction braze welding). The process is particularly suitable for simple joints in electrically conductive metals. 

Furnace Brazing 

Furnace brazing offers two major benefits. Protective atmosphere brazing, where vacuums or high-purity gasses cut the need for fluxes, and precise control of every heating and cooling phase. Heating can be either via gas firing or through elements. 

Dip Brazing

The assembly gets immersed in a bath of molten flux or braze alloy in this process. The parent metal’s bath temperature is below its solidification point but above the filler metal’s melting point. 

How Does Welding Work?

A welding filler metal added to a joint will create a welded bond between metals. This happens by melting and fusing them. Concentrated heat on the joint area will fuse the two metals.

The welds are strong, usually as strong as the metals themselves or even stronger. Because the base metals and filler metals must melt to fuse them. Welding begins at the melting point of the base metals.

When using large metal sections with a single point of attachment, welding is often used. The welded joint will be irregular, so it is not fit for use in products requiring cosmetic joints.

Implementation is available in construction, transportation, manufacturing, and repair. Examples include robotic assemblies and fabrication of bridges, pressure vessels, building structures, aircraft, railways, railway coaches, and pipelines. 

You cannot use welding heat over a large area because the heat needs to be exact. Localizing and concentrating the heat has its advantages.

For example, an electrical resistance welding approach may be useful to join two small pieces of metal at a single point. This approach can generate hundreds and thousands of strong, permanent joints in a fast and economical manner. 

Types of Welding 

There are various types of welding options for your specific need. Here are a few common welding methods:

Arc Welding 

The earliest welding technique ever created was arc welding. This method uses an electrical current to melt and bond together aluminum sheets. Despite being one of the most economical methods of welding aluminum, only experienced welders should handle arc welding. 

Resistance Welding

You can also work with aluminum using resistance welding. But, there are several issues. This is because of aluminum’s high thermal conductivity. You will need special welding equipment and time establishing parameters to successfully finish the weld.

Laser Beam and Electron Beam Welding

Electron beam welding is far less difficult to execute. It is performed in a vacuum, so it does not consume light as a power resource, and it does not suffer from porosity. Even though both laser and electron beam welding techniques have drawbacks.

Beam welding creates a high-power density, which is beneficial because it prevents cold starts. Laser welding has a variety of problems, including light reflectance and porosity. You may prevent porosity if you optimize the shielding gas.

Is Aluminum Brazing Stronger Than Welding? 

When comparing the strength of welded joints with brazed ones, a well-executed welded joint will often be just as strong. You should weigh which method is better for the job. Even if joints produced by welding are stronger, brazing is better in some situations.

Are you involved in a project that could use aluminum brazing? In addition to being a thought leader in the aerospace and military manufacturing sector, NAMF is a trailblazer in the production of precision machined parts and durable dip-brazed enclosures. Contact us or visit our Blog which is packed with helpful information.