Welding is one of the most effective ways of joining metal in fabrication. Generally, all types of welding can produce extremely strong bonds. However, is one type of welding better than the other?
The type of welding isn’t the only thing that can determine the strongest weld. Factors such as the material or metals, the weld length and size, the filler used, and even the skill of the operator or welder come into play.
Understanding the different types of welds and where they are best applied can be confusing. That’s why we have created this guide to help you better understand the factors that influence welds.
What Are The Different Types Of Welds?
There are several types of welds. The four most common ones are MIG, TIG, Stick Welding, and Arc Welding.
Over the years, other welding methods have also emerged like Laser Welding, Plasma Arc Welding, MIG Brazing, Submerged Arc Welding, Spot Welding, Friction Welding, and Explosion Welding.
What Is MIG Welding?
MIG stands for Metal Inert Gas and is sometimes known as Gas Metal Arc Welding (GMAW).
With traditional MIG welding, you use a welding gun, a power supply, a wire feed unit, a consumable welding electrode wire (that is both the filler material and electrode), and a protective or shielding gas supply. Compared to TIG welding, components for MIG welding are much more accessible and less expensive.
When MIG welding, the electrode wire creates an arc with the base metal you are welding, melts it, then fuses the two materials together. A protective gas bubble is also made in this welding process. This protects the weld from outside contamination. This type of weld isn’t ideal for use outdoors, in places with moving air or particularly wet areas.
MIG has been called the “hot glue gun” of welding because “fusing” with MIG welding is quite tricky. Its electrode wire simply acts as a glue between two materials, unlike TIG, which actually melds the two materials together. So when you’re MIG welding, you can weld various kinds of metals together. It’s more commonly used on aluminium, steel and stainless steel, heavy-duty structural plates, and 26-gauge sheet metal. However, it is too weak for cast iron and too strong for thin aluminium.
One huge benefit of MIG welding is that it can speed up production and decrease lead time. It’s also quite easy to automate. MIG is also relatively easy to get used to and master in a few weeks. In fact, some MIG welders can operate the welding gun one-handed. Regardless, welders who aren’t adequately trained will still produce poor quality welds.
However, some common quality problems with MIG welding are weak and less ductile welds are sometimes produced. Dross, which is like a mass of metal scum, and porosity, which refers to gas entrapment in the weld before cooling, are also standard quality issues because of impurities in the material or shielding gas. To prevent these issues, avoid materials that are too thick or too thin and materials that are impure or dirty.
What Is MIG Welding Good For?
MIG welding is most commonly used in industrial processes, such as high-production manufacturing. It has been used in ship and boat parts, computer parts, mining equipment, agricultural products, and even home and office furniture.
It’s also suitable for repairs and assemblies in the automotive industry, with applications on cars, bikes, vans, and RVs. It has been used in RV conversions, caravan fit-outs, and vehicle customisation.
MIG is used in construction, too, because we all know steel is king in the construction industry.
This type of welding has even been used to 3D print metal objects, making it a low-cost alternative to 3D printing. Thus, it’s also sometimes used to do metal sculptures.
What Is TIG Welding?
TIG stands for Tungsten Inert Gas, and it’s also sometimes known as Gas Tungsten Arc Welding (GTAW). TIG welding is extremely hot, and it’s quite a challenging style of weld to master, but welders have developed clever techniques over the years.
TIG welding is also manual. You’ll need a welding torch, a constant-current welding power supply, an electrode of your choice, a gas for shielding, and sometimes a grinder and filler metals. You’ll also have to pick between hand control or pedal control, but most welders use both of their hands for TIG.
Unlike MIG, its electrode is non-consumable and is made of tungsten, so you will eventually have to purchase tungsten after several uses for maintenance. The tungsten can be found in the torch.
Now, because tungsten is non-consumable in TIG, the electrode is tungsten. However, other tungsten alloys have been allowed for in TIG too. You can use pure tungsten, thorium oxide or thoria, cerium oxide or ceria, lanthanum oxide or lanthana, or zirconium oxide or zirconia.
As for the shielding gas, the type you choose depends on the material being welded, the joined design, and the finish you desire. Some of your choices are argon, which is the most common and results in high weld quality and good appearance, and helium, usually used for copper, aluminium, and other high conductivity metals.
TIG is usually used for welding nonferrous materials, like aluminium and magnesium, and most other metals (nickel, titanium, copper, etc.) except for zinc and zinc alloys. For welding dissimilar metals using TIG, a compatible filler metal is needed. The result of TIG welding is a robust and high-quality fusion.
TIG welds are thin and precise because the tungsten rod is thinner than a stick rod. As a result, it can produce some good-looking joins. In fact, even though you aren’t welding in a flat position, it’s still possible to use TIG precisely.
However, a downside to TIG is it can be slow and time-consuming. And even though its electrode is non-consumable, the TIG machine is costly initially. Only professional hands should be allowed to operate and maintain it. It should also only be done by professionals; beginners will have to overcome a steep learning curve to truly master this as TIG equipment is complicated.
What Is TIG Welding Good For?
TIG has been used in industrial equipment, like sheet metals.
Automotive, aviation, aerospace vehicles, and parts have also benefited from TIG Welding. There are TIG strategies known to decrease the effect of corrosion, so it’s the go-to for safe and secure construction. One big project that utilised TIG is the Internal Space Station.
Furnishings, simple repairs, and metal sculptures also use TIG. For instance, it can weld a child’s toy like an old-fashioned pedal car. It can also be used in artworks that require a nicer finish than MIG. Some domestic and industrial fixtures may also use TIG welding, like a metal chandelier.
TIG is also used in pipeline and pipe welding because its strength can withstand water pressure.
What Is Stick Welding?
Stick Welding is sometimes known as Shielded Metal Arc Welding (SMAW) and Manual Metal Arc (MMA) Welding.
To stick weld, you need a stick welder, a ground clamp, your choice of electrode, and slag removing tools. When you’re stick welding, you create a layer of slag that protects the weld pool from being contaminated by the atmosphere. You really have to get some grinding done afterwards. This weld also uses a consumable rod.
There are tons of electrodes used for stick welding, and they are usually labelled with four digits. The first two digits show the minimum tensile strength, which will need to match your base metal strength properties. The third digit refers to the electrode’s positions when welding: 1 is for any position (like TIG), and 2 is for flat position only (like MIG). The fourth and last digit is the current that you can use and the coating on the electrode.
Unlike MIG and TIG, which are ideal to be done indoors or in places where the air doesn’t move, Stick Welding can be done outdoors. Welders prefer this because of the cheap and portable equipment and durability, even in bad weather.
Stick Welding can use a variety of electrode sizes. It can produce strong welds even on thick materials, like cast iron. Stick Welds, like TIG, fuse the materials together by heating them to a high enough temperature. However, Stick Welding isn’t suitable for thin materials.
Given the difficulty in striking an arc, stick welding is easier to learn than TIG welding but harder to grasp than MIG welding. Some of the common mistakes stick welders make are having the wrong drag angle, having an arc that’s too long, and welding at the wrong speed and temperature. These errors can cause a lumpy weld bead that requires grinding and finishing touches afterwards.
Other drawbacks of Stick Welding include spatter and slag. It’s also slow like TIG, and it requires frequent replacement of its stick or electrode, more often than MIG electrodes. It’s also not ideal to use Stick Welding on titanium, zirconium, tantalum, columbium, and other reactive metals.
What Is Stick Welding Good For?
Stick Welding is used in structural construction weldings, such as constructing infrastructures, like roads, buildings and bridges. It’s also used in manufacturing, steel fabrication, and field repair.
Stick Welding can also be applied in shipbuilding, aerospace, mining, marine, and nuclear fields. It’s also the go-to of hobbyists as Stick Welding equipment is portable.
What Is Arc Welding?
Arc welding is a welding type that joins two materials using electricity. The welding area can be protected by shielding gas, slag, or vapour. Under arc welding are more specific welding types such as MIG, Metal Active Gas (MAG), Shielded Metal Arc Welding (SMAW), and Fluxed Core Arc Welding (FCAW) which all use consumable electrodes or rods. TIG and Plasma Arc Welding (PAW) are also types of arc welding, but they use non-consumable electrodes.
For those that use consumable rods, the electrode is usually made of metal that melts while the materials are being welded. This is common in the manufacturing of steel products. Meanwhile, arc welds that use non-consumable electrodes aren’t melted during the welding process.
The electric power supply of Arc Welding can also vary, from direct current (DC) to alternating current (AC). DC Arc Welding is more commonly preferred because the flow of electrons is steady and smoother. It’s also ideal for low-voltage cases. AC is the go-to when a stronger current is required or when electricity needs to be transmitted over large distances.
What Is Arc Welding Good For?
Because of the subtypes of Arc Welding, there are various uses for it. The applications of MIG, SMAW, and TIG are already discussed in the earlier sections, so let’s focus on applying the other types of Arc Welding.
As for MAG welding, it’s used in low-alloyed construction steels and on thin and moderately thick sheet metals. For instance, it’s used in car bodywork services.
FCAW is used in shipbuilding, construction, and the mechanical industry. It can be used on plain carbon alloy, stainless steel, duplex steel, and hard facing and surfacing.
PAW applications include the marine, aerospace, and electronics industries. It’s also suitable for mechanised welding processes, like welding stainless steel or titanium pipes and tubes—additionally, repair of tools, moulds, and dies benefits from PAW.
What Type Of Weld Is The Strongest?
TIG welding is often considered the strongest weld since it produces extreme heat, and the slow cooling rate results in high tensile strength and ductility. MIG is also an excellent candidate for the strongest type of weld because it can create a strong joint.
However, this question is actually quite tricky as the strength of a weld depends on the material it’s used on. Three other criteria to look at that can determine the strength of a weld are the weld length, size, and filler.
Thus, the answer to the question ‘What is the strongest type of weld?’ isn’t clear cut and depends on the welder’s skill and the material used.
What Joint Is Strongest To Weld?
Most people consider the strongest joint to weld to be arc welding a corner or tee joint with a groove. However, similar to ‘what type of weld is the strongest,’ the question ‘what joint is the strongest to weld’ is also tricky to answer as this depends on the material and skill of the welder. Alongside skill, the reinforcement, angle and penetration of the weld itself will all affect the strength of the joint.
What Can Weaken A Weld?
The top three things that can weaken a weld are impurities, improper heating, and porosity.
Impurities or slag like dirt, debris, and even rust will make a weld, especially a joint, lack uniformity. Those will create bumps and pockmarks on your weld, which, even if you grind, will still weaken the integrity of your weld. Make sure you clean and prepare your materials before the weld to avoid this.
Improper heating can cause cracks and poor mechanical properties of the weld (tensile strength, ductility, etc.). This could be because of improper preheating and post-heating, like overheating or underheating or not annealing when it’s required. Some signs of improper heating are cracks adjacent to the joint and extreme discolouration.
Porosity or the trapping of corrosive gases (hydrogen, oxygen, nitrogen) can also result in cracks, which weaken a weld. Some signs of porosity are holes in the metal. This can be prevented by using the proper shielding gas when welding.
Other things that can weaken a weld are oxidation and corrosion, which happens over time.
Is Welded Steel Weaker?
Welding weakens steel in the heat-affected zone. After welding, the joint should be stronger than the base materials. This is achievable if there is more cross-sectional area in the bead and the weld bed is made of a stronger material.
People often debate this and say that only good or experienced welders can achieve a stronger weld than the base material.
Are All Metals Safe To Weld?
Yes, all metals can be welded, but the properties of different types of metals you attempt to weld can create safety issues.
For example, it might be ideal to use TIG when you have carbon steel, stainless steel, or aluminium. If you have thin aluminium, it’s best to avoid MIG. Some people also weld dissimilar metals (metals with different alloys), but significant consideration for the type of weld and filler is necessary.
What Metals Can’t Be Welded?
Generally, all metals can be welded together, but some materials aren’t ideal to be welded, like aluminium to stainless steel, carbon or titanium.
There’s a concept called dissimilar metal welding, which joins incompatible materials or alloys together. Transition materials or non-standard methods of welding apply in order to do this. Thus, this can’t be done by beginner welders. Some things they have to consider joining dissimilar metals are the composition of the intermetallic layer, the unmixed zones of the base materials, and the heat-affected zone.
Some non-standard welding techniques used are fusion welds, low-dilution welding, and non-fusion joining (friction welding, diffusion bonding, soldering and explosion welding). Non-fusion joining is used to join aluminium and steel.
Graham Dawe is the Managing Director and Works Manager of Kanyana Engineering. With decades of experience in the metal fabrication industry, he is dedicated to keeping Kanyana at the forefront of the sector’s technological growth. Looking beyond the process itself to holistic, integrated CAD, CAM and MRP solutions, Graham believes Australian manufacturing has an enduring place on the global stage. In Kanyana Engineering’s state-of-the-art workshop in Mandurah, WA, Graham delivers an exceptional standard of work for commercial, industrial and government clients alike.