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Welding Vs Brazing Vs Soldering: Key Differences and Applications
Welding, brazing, and soldering are all metal joining processes. Manufacturers and metal fabricators use these techniques to join two pieces using heat and a filler metal or an electrode.
However, each method is unique. Welding utilizes the heat of an arc that reaches extremely high temperatures, melting and fusing the pieces. Meanwhile, brazing and soldering occur at much lower temperatures. The heat melts the filler without reaching the melting temperatures of the base metal.
Since many beginners often confuse these three, we have compiled a detailed article on welding, brazing, and soldering. Continue reading to discover the fundamentals and key differences between each.
Welding, Brazing, and Soldering
Metal fabricators use welding, brazing, and soldering to join two metal pieces in everyday applications. All three techniques use heat to produce a bond, which can be confusing for some beginners.
However, fundamentally, welding is much different than brazing and soldering. Brazing and soldering are somewhat similar, but there are still some differences.
To begin the article, we will provide a brief overview of the fundamentals of each metal joining technique. Understanding how each method works is crucial in determining which one is best suited for your home metal joining applications.
Welding, Brazing, and Soldering Comparison
What is Welding?
Welding, a versatile and broad term, encompasses a range of metal joining processes. These processes can use multiple heat sources, such as arc, friction, laser, resistance, or electron beams, to melt and fuse the pieces. The most widely used process across the home and in everyday use is arc welding.
Arc welding processes, such as MIG welding, TIG welding, or Stick welding, use the heat of an arc to melt and fuse pieces. Arc forms between the electrode and the base metal. The electrode is connected to one side of the terminal, and the base metal is connected to the other. The arc starts once you close the circuit between them.
The arc reaches intense temperatures, typically ranging from 6,000°F to 10,000°F. This heat melts the base metal and filler metal or consumable electrode, forming a weld puddle. Once the weld puddle solidifies, it forms a weld bead, creating a strong and everlasting bond between the two pieces.
Molten weld puddles tend to pick up contamination from the atmosphere. They react with atmospheric gases such as hydrogen or oxygen, causing oxidation, porosity, or weld cracking. That's why welders use external shielding gas, self-shielded electrodes, or wires that contain flux.
When done correctly, welds create a strong bond that can withstand high temperatures and various types of stress. Today, dozens of techniques are used to join most metals known to humankind. Welded components are used in multiple aspects of everyday life, including airplanes, bridges, buildings, cars, and ships.
Some Examples of Welding Applications
Advantages of Welding
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Creates a strong bond resistant to heat, stress, and other harsh conditions.
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The welds are much stronger and more heat-resistant than brazing or soldering.
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It can join various metal types.
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Works well with thin and thick pieces.
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Produces exceptional weld quality.
TIG welding delivers clean, precise, and high-quality welds.
Photo by @random_video_studio92 (TikTok)
Drawbacks of Welding
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High heat exposure can lead to significant thermal distortion and residual stresses compared to brazing and soldering.
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It can cause cracking or distortion on delicate, thin, or heat-sensitive metals.
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It works best with similar metals but falls short in dissimilar metal joining.
Welding Dissimilar Metals for Piping Repair
Source: https://www.youtube.com/watch?v=Ug_cToF_ryA
What is Brazing?
Brazing is another metal joining process that uses heat to join the pieces. However, the heat source is often the torch that produces a much lower temperature than welding.
What is Brazing?
Source: https://www.pcbdirectory.com/community/what-is-brazing
The most common brazing temperatures range from 900°F to 2200°F. Old AWS definitions define brazing as a process that occurs at temperatures above 840°F (454 °C). Anything below can be characterized as soldering.
Heating the pieces at 900°F or higher means the brazing doesn't reach the melting temperature of the base metal. So, compared to welding, only the filler metal melts. Leaving the base metal intact reduces the overall heat exposure, but it also allows welders to join dissimilar metals.
As the filler metal melts, the capillary action pulls it into the joint. To achieve this action, you need a tight part fit-up and flux. These two components protect the braze welds from contamination and facilitate the formation of a continuous bond between thin pieces.
Brazing Aluminum to Copper
Source: https://www.youtube.com/watch?v=BySIwLT0Uzs
The flux is an essential part of brazing and soldering as it:
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Removes the oxides as the parts heat.
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Promotes wetting, in which a liquid filler metal or flux spreads and adheres in a thin, continuous layer on a solid base metal.
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Aids in capillary action by pulling the molten alloy into the joint.
Using Flux While Brazing
Source: https://www.dodomachine.com/
Fluxes come in various forms, such as solids, powders, pastes, liquids, sheets, rings, and washers. The key is to match the flux and filler metal combination, as well as the base metal and brazing filler metal. To do so, you can follow the AWS classifications.
Brazing Filler Metal Selection Chart
Source: https://www.uti.edu/blog/welding/brazing-soldering-welding
Advantages of Brazing
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Lower heat means lower heat input onto the pieces and joints.
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Significantly lower thermal distortion and residual stresses compared to welding.
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It doesn't melt the base metal pieces, so it can join dissimilar metals.
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No need for post-processing or heat treatment
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Produced joints are stronger than soldering
Brazing Copper Tubing
Source: https://www.engineersgallery.com/brazing/
Drawbacks of Brazing
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Lower joint strength compared to welding
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Joints are not suitable for high-temperature applications.
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Fluxes may contain toxic substances.
Brazing Process
Source: https://www.harrisproductsgroup.com/
What is Soldering?
Soldering, a metal joining process similar to brazing but with some key differences, is known for its precision and accuracy. It utilizes significantly lower heat than welding and brazing, making it ideal for electronics and fine metalwork.
Soldering for Fine Metalwork
Source: https://davidneat.wordpress.com/2015/05/03/a-quick-guide-to-soldering-brass/
As noted above, soldering occurs at temperatures lower than 840°F. These low temperatures are ideal for softer filler metals, such as tin-based alloys, and applications where precision and minimal thermal impact are crucial.
Soldering works quite similarly to brazing. A tool known as a soldering iron applies heat, melting the solder. Flux cleans and protects the surfaces, allowing for the easier flow of the liquid filler metal over the base material.
What is Soldering？
Source: https://www.makerspaces.com/how-to-solder/
Unlike welding or brazing fillers, solder is soft and comes in tubes and reels. Most solders today consist of antimony, bismuth, copper, indium, tin, or silver. In the past, lead-based solders were predominant; however, due to health risks and new regulations, the situation has changed.
As the solder melts, it forms a bond that is weaker than one formed by welding or brazing. Since soldering occurs at lower temperatures, the bonds are not resistant to heat. Depending on the applications, soldering may or may not have capillary attraction.
Although not that strong, the soldering bond conducts electricity. That's why it's often used for electrical connections, in applications such as joining copper to printed circuit boards (PCBs), plumbing, or jewelry making.
Soldering Printed Circuit Boards
Source: https://www.globalwellpcba.com/solder-joints/
Advantages of Soldering
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A very low heat input limits thermal distortion and residual stress in the base metal.
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Best suited for delicate designs and parts, such as electronics.
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Like brazing, base metal doesn't melt. As a result, it can successfully join dissimilar metals.
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No need for post-processing or post-heating treatment.
How to Solder
Source: https://wiki.cci.arts.ac.uk/
Drawbacks of Soldering
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Produces the weakest bonds among the three metal joining techniques.
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Not suitable for high-temperature applications.
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It cannot join larger metal sections.
Soldering Fine Metal Process
Source: https://ipsystemsusa.com/
Key Differences Between Welding, Brazing, and Soldering
To better understand the key differences between welding, brazing, and soldering, we will closely focus on the crucial parameters, including:
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Strength of the joint
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Source of heat
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Heat input and temperatures
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Changes in base metal
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Use of flux
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Base metal heat treatment
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General applications
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Costs
Getting familiar with each can help you make an informed choice for your next home metal fabrication project. Here is a quick comparison table of welding, brazing, and soldering:
|
Welding |
Brazing |
Soldering |
|
|
Strength of the bond |
Strongest bonds resistant to heat and stress |
Weaker than weld, but can bear some load |
The weakest bonds among the three |
|
Heat source |
Arc, laser, resistance, friction, or electron beam |
Torch, furnace, or induction systems |
Soldering iron, torch, or hot air gun |
|
Heat input and temperatures |
High heat input up to 10,000°F or more |
Moderate heat over 840°F, but typically between 1100°F and 1500°F |
Lowest heat below 840°F, mostly between 600° and 700°F, or as low as 350°F |
|
Flux |
Not mandatory, mostly used in SMAW and FCAW |
Crucial component |
Used in many applications, but not mandatory |
|
Changes in base metal |
Base metal melts, causing changes in mechanical properties |
Negligible changes |
No changes in mechanical properties |
|
Heat treatment |
Depends on applications, but often not needed on regular mild steel |
Preheating can improve brazing results |
Preheating can be helpful, but it is not always necessary |
|
General applications |
Structural steel, construction, pipeline, shipbuilding, rail, nuclear, aerospace, and general metal fabrication, among others. |
Plumbing work, HVAC, and refrigeration |
Electronics, plumbing work, jewelry making |
|
Costs and skill requirements |
The most expensive equipment and the highest skill requirements are among the three. |
Medium costs and skill requirements |
Lowest costs and skill requirements |
Below is a detailed breakdown of each parameter, along with the key differences between noted metal joining processes.
Welding vs. Brazing vs. Soldering
Source: https://www.cruxweld.com/
Strength of the Joint
Welding: When it comes to strength, welding produces the strongest joints among the three metal joining procedures. Welded joints can withstand high temperatures and stresses. Welds are often as strong as, and sometimes even stronger than, the base materials. This strength makes welding the backbone of various industries and structural applications.
Strong Welded joints
Photo by @camwelds (TikTok)
Brazing: Brazed joints provide some strength, as they can withstand a specific load. For example, brazed pipes must resist water hammering, but there is a maximum load they can bear. That's why brazed joints are not essentially structural.
Soldering: Soldering produces the weakest bond among the three metal joining procedures. They can conduct electricity and handle electrical forces, but not tensile, linear, or shear stress. Soldered joints are not designed to withstand stress or force, and they shouldn't be exposed to such conditions.
Demonstration of Precision Soldering on a Circuit Board
Source: https://www.youtube.com/watch?app=desktop&v=eLw0AA9LU5M
Source of Heat
Welding: Depending on the method, welding can use the heat of an arc, resistance, laser, friction, or electron beam to melt and fuse pieces. Regardless of the heat source, most methods produce intense heat that melts and fuses the pieces with or without filler metal (autogenous welding).
Brazing: In brazing, the heat is supplied by an air-fuel or oxy-fuel torch, furnaces, and induction heating systems. Depending on the applications, these torches produce enough heat to heat the pieces and melt the filler metal. However, the torch should never melt the base metal.
Soldering: Depending on the application, soldering uses a soldering iron, torch, or hot air gun as a heat source. These sources produce the lowest heat among the three methods, which is sufficient to melt the soft solder.
Comparison of Heat Sources: Welding vs. Brazing vs. Soldering
Source: https://blog.red-d-arc.com/
Heat Input and Temperatures
Welding: Welding heat sources produce the highest heat among the three metal joining procedures. The heat of an arc can reach 10,000°F or even more. However, keep in mind that there are also low-amp, low-temperature applications for delicate and thin pieces. Regardless of the method, the heat should be sufficient to melt and fuse the pieces.
Brazing: Brazing is a middle-temperature application. AWS states that it occurs over the 840°F range; however, in plumbing and copper systems, most brazing occurs at temperatures between 1100°F and 1500°F. The heat depends on the properties of the brazing filler and flux. Regardless of the exact temperature, brazing should melt the filler metal, not the base metal.
Soldering: Soldering is the lowest-temperature metal joining process among the three. As noted, brazing occurs at temperatures lower than 840°F. Most lead-based solders require temperatures of 600°-650°F, while lead-free solders melt at 650°-700°F. Copper system applications require even lower temperatures, ranging from 350 to 550°F. The lowest heat input is ideal for delicate and heat-sensitive metals.
Temperature Differences: Welding vs. Brazing vs. Soldering
Source: https://www.youtube.com/watch?v=GER8xXvFgNI&t=3s
Changes in Base Metal
Welding: In welding, the base metal is melted, mixed with filler metal, and then solidified once again. This process can cause changes in the molecular, physical, and chemical structure of the metal. On challenging metals such as high-carbon steel or cast iron, these changes can make welds prone to cracking. Altering the base structure of the metal means welding is often not recommended for dissimilar metal welding, although you can join some with similar compositions.
Brazing: Since brazing occurs at much lower temperatures than welding, it doesn't reach the melting point of metals. However, some brazing fillers may require more heat, which can result in a negligible change to the base metal's structure. Nonetheless, the flux protects the base metal, so brazing can join dissimilar metals.
Soldering: Soldering does not alter the mechanical properties of the joined pieces. Since it occurs at the lowest temperatures, the properties of the base metal stay intact, allowing you to join delicate and dissimilar pieces.
Soldering on Circuit Board
Photo by @wonderfulpcb_official (TikTok)
Use of Flux
Welding: Some methods, such as Stick welding (SMAW) or Flux-core arc welding (SMAW), use flux as a part of a self-shielded electrode or wire. This flux forms a layer of slag that protects the weld from atmospheric contamination, eliminating the need for an external shielding gas. However, flux is not mandatory for all welding.
Brazing and soldering: Flux is a crucial component in brazing and soldering. The flux protects the base metal from oxides formed by heating, promotes wetting, and aids in capillary action by pulling the molten alloy into the joint. As a result, it protects the metal from heat and allows the molten filler to distribute evenly along the joint. However, flux is not needed in some soldering applications.
Use Flux When Brazing
Source: https://www.harrisproductsgroup.com/
Base Metal Heat Treatment
Welding: Since welding occurs at high temperatures, preheating or post-heating on standard mild steel is not necessary. However, metals with high carbon content tend to crack due to thermal stress or quick heating and cooling. In these applications, preheating and slow cooling are crucial in preventing weld failure.
Brazing: It is good practice in brazing to preheat the base metal before adding and melting the filler. Preheating helps the filler material distribute evenly along the joint and adhere wetly to surfaces. Conversely, brazing requires no post-heating; it can even harm the newly formed bond.
Preheating Before Brazing
Source: https://www.youtube.com/watch?v=L5jXxG3WC5A
Soldering: Soldering can also benefit from some preheating. However, the need depends heavily on the purpose and physical needs of the joint. In most applications, preheating or post-heating processing is not necessary with soldering.
General Applications
Welding: Often used in applications where parts are subjected to high temperatures or stress. Typical examples include structural welding, heavy machine manufacturing and repair, the pipeline industry, the construction industry, and railroad or shipbuilding. However, fine welding forms such as laser welding or TIG welding are used in delicate components and parts, including those for aerospace, nuclear, or medical tool manufacturing.
Stick Welding for Pipes
Photo by @curtismartin680 (TikTok)
Brazing: Brazing is mainly used in applications where two pieces need to be joined without melting them. A typical example is copper tubing used in plumbing, HVAC, and refrigeration systems.
Soldering: Widely used in electronics and electrical work to create precise, low-temperature connections between components, such as circuit boards, wires, and connectors. It also finds applications in plumbing and jewelry making.
Soldering Wires
Source: https://www.youtube.com/watch?v=NSqPHQ1zQco
Costs and Skill Requirements
Welding: Of the three, welding requires the most expensive equipment, including welding machines, accessories, and consumables. It also requires the highest skill requirements and longer training. However, if you don't want to pay a fortune for welding equipment, be sure to check out our welders, such as the YesWelder DP200 Multi–process welder.
Brazing: When it comes to costs and skill requirements, brazing falls between the other two metal joining methods. The equipment is not so expensive, as you'll need a suitable torch, brazing fillers, and flux. Learning how to braze is not so complex.
Soldering is the most cost-effective method, as it requires only small amounts of solder and a soldering iron to complete most jobs. Although it takes some time and precision to master delicate electronic works, you can learn how to do it fast.
Source: https://stellartechnical.com/
Final Thoughts
Welding, brazing, and soldering are essential metal-joining techniques, each suited to specific applications based on temperature, strength, and precision requirements. Welding provides the strongest joints by melting base metals, making it ideal for structural and heavy-duty applications.
Brazing utilizes a filler metal at moderate temperatures to bond dissimilar metals, resulting in high strength and minimal distortion. These characteristics make it a valuable process in the HVAC, automotive, and aerospace industries.
Soldering, with its low-temperature process, is ideal for delicate tasks such as electronics and fine metalwork. Understanding their differences helps in selecting the most effective method for a given application, balancing strength, temperature limits, and material compatibility.
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