Types of Welding Techniques
Welding is the art and science of binding metals, but it’s not a one-size-fits-all operation. Every metal and welding purpose requires a distinct technique, meaning that every job should be treated differently. That is why, at Lenoch Engineering, we stay updated with industry trends and utilise dependable welding methods for consistent, optimal outcomes. With that in mind, let's explore some of the most common welding techniques.
MIG (GMAW) Welding
MIG welding, formally known as Gas Metal Arc Welding (GMAW), is a versatile welding method that is used in many fabrication and repair settings. This technique is characterised by the use of a continuously fed wire electrode, which, when combined with a shielding gas, welds two materials while preventing contamination from atmospheric particles.
MIG welding's remarkable trait is its adaptability. Not only can it handle a range of metals and alloys, but it can also be tailored to suit various thicknesses, making it a useful tool for both thin sheet welding and heavy structural repairs.
MIG welding is also a fast and efficient form of welding. The continuous wire feed allows for a faster deposition rate compared to other welding methods. This makes it ideal for high-volume production applications where time is a crucial factor. Additionally, the ease of automation with MIG welding further enhances its speed and productivity.
TIG (GTAW) Welding
TIG welding, or Gas Tungsten Arc Welding (GTAW), is renowned for its precision. The technique employs a non-consumable tungsten electrode to carry the current to the welding arc, setting it apart from other methods as the electrode isn't consumed during the process. The finesse of TIG welding is particularly evident when dealing with thin and detailed workpieces. There's a reduced risk of warping, which makes it the method of choice for detailed tasks or ornate designs.
Another significant benefit of TIG welding is its versatility. It can be used for both thin and thick materials, making it suitable for a variety of applications, from the automotive and aerospace industries to delicate jewellery. TIG welding also provides excellent weld aesthetics, producing clean and visually appealing welds with no spatter or slag left behind.
Furthermore, TIG welding offers exceptional control over the welding process, allowing for precise manipulation of the weld pool, filler metal, and shielding gas. This control allows welders to achieve accurate weld profiles and intricate weld designs. Additionally, TIG welding enables the use of various welding positions, making it suitable for welding in challenging positions or tight spaces.
Stick (SMAW) Welding
Stick welding, formally known as Shielded Metal Arc Welding (SMAW), stands as one of the earliest and most extensively employed manual arc welding methods. Its key benefits lie in its simplicity and versatility. It involves creating an electric arc between the rod-like electrode and the materials to be joined. This arc melts the electrode and forms a weld pool, combining the molten electrode and base material. resulting in a sturdy bond.
One of the defining features of stick welding is the protective flux coating on the electrode. As the welding progresses, this coating decomposes, releasing gases that shield the weld from external contaminants, ensuring a cleaner weld. Additionally, the slag produced on cooling provides further protection against atmospheric contamination, although it needs to be chipped away post-welding.
At its core, Oxy/Gas Welding harnesses the power of a precisely controlled flame, produced by the combustion of oxygen combined with a fuel gas, typically acetylene. The heat from this flame, which can reach temperatures upwards of 3,500°C, is skillfully employed to melt and join metals together.
One of the main advantages of this welding process is its versatility. Oxy/gas welding can be used on various types of metals, including steel, stainless steel, aluminium, and copper. This versatility allows for a wide range of welding projects, from small repairs to large-scale fabrications.
The high temperatures generated by the combustion of acetylene gas enable the welding of even thick materials efficiently. Moreover, oxy/gas welding does not require electricity, making it a portable and convenient option for remote locations or areas with limited power access. Consequently, it is a low-cost welding process, as the equipment is relatively inexpensive, and the gases used, oxygen and acetylene, are readily available and affordable.
It’s worth noting that Oxy/Gas welding is one of the few processes that can be used for brazing, a technique in which filler material is melted at a temperature above 450°C but below the melting point of the base metals.
Considerations When Choosing the Best Metal for Welding
Strength and Durability
The resilience of a weld hinges on the strength and durability of the chosen metal. It’s not just about making two pieces stick; it’s about ensuring they withstand the test of time and the stress they are put under. Metals that display robust tensile strength often yield welds that can bear substantial loads. For applications like construction or heavy machinery, this consideration becomes paramount.
Not all materials can be easily matched. The properties of the base metal, such as its chemical composition and tensile strength, play a crucial role in determining compatibility with the filler metal.
Different metals have varying chemical compositions, and using a filler metal with a significantly different composition can lead to poor weld quality. The filler metal should ideally have a similar chemical composition to the base metal, ensuring that they can be effectively fused together during the welding process.
Alternatively, when considering tensile strength (the ability of a material to withstand pulling or stretching forces without breaking), if the filler metal used has a lower tensile strength than the base metal, the joint may be weaker and prone to failure. If the filler metal has a higher tensile strength, it can lead to cracking or distortion in the welded joint due to the mismatched strength properties.
While strength is an important factor, it’s not all about finding the strongest material. Matching the filler metal to the base metal's chemical composition and tensile strength helps to ensure that the resulting weld joint possesses the desired mechanical properties. It helps to maintain the structural integrity of the welded component, ensuring that it can withstand the intended operating conditions and loads.
Ductility and Weldability
Ductility - the metal's ability to be reshaped without breaking - plays a pivotal role in weldability. A highly ductile metal can be welded with ease, ensuring malleability under heat and allowing for solid joint formation. Metals that resist this malleability often result in less-than-optimum welds, prone to cracks and faults.
Over time, metals are prone to environmental wear, notably through corrosion. Metals boasting high corrosion resistance are especially desirable, especially for welds subjected to moisture, chemicals, or fluctuating temperatures. Even a skillfully welded non-resistant metal could deteriorate, putting the weld's strength at risk. This is especially true in industries such as marine or chemical processing.
Financial considerations are always important when selecting the best metal for welding. While it may be tempting to choose premium metals, budget limitations are a reality that needs to be factored into the decision. Opting for an affordable metal does not mean compromising on quality. It is possible to find a balance between a metal that meets your welding requirements and is also cost-effective.
The Best Metals for Welding
Now, let’s take a look at the most commonly used and effective metals for welding that are currently available.
Low Carbon Steel
- Welding Process: Best suited for MIG and Stick welding.
- Core Properties: Malleable, with great tensile strength.
- Applications & Benefits: Often found in car housing and heavy machinery, low-carbon steel is affordable and easy to weld with, making it the preferred choice for most general-purpose welding jobs.
- Welding Process: TIG welding fits best.
- Core Properties: Low-density, lightweight and highly conductive.
- Applications & Benefits: Because of its weight-to-strength ratio, aluminium is invaluable in the aircraft and automotive industries.
- Welding Process: Stick welding is preferable.
- Core Properties: Hard, yet brittle.
- Applications & Benefits: Durable and wear-resistant, cast iron is often seen in engine blocks and various machine tools, offering long-term stability of build.
- Welding Process: TIG and MIG welding are ideal.
- Core Properties: Resistant to corrosion and oxidation.
- Applications & Benefits: Stainless steel's high resistance to rust makes it perfect for kitchenware, medical instruments, and exterior design elements, amongst other things.
- Welding Process: MIG, TIG, and Gas welding are commonly used for welding copper and its alloys.
- Core Properties: Excellent conductivity and malleability.
- Applications & Benefits: With its excellent conductivity, copper is often used in electrical components, making it a vital component in maintaining electrical infrastructure.
- Welding Process: TIG welding is optimal.
- Core Properties: Renowned for high temperature (with a melting point of 1453°C) and corrosion resistance.
- Applications & Benefits: Predominantly found in aerospace and marine environments. Notably, alloy type 131 is favoured for its superb oxidation resistance, type 61 is praised for its adaptability in varied temperatures, type 190 excels in high-temperature scenarios, while type 60 showcases impressive strength under corrosive conditions. These specific types underline nickel alloys' capability to perform exceptionally in a range of diverse settings.
By now you should have a better understanding of the different types of welding and which materials best suit them.
Depending on your project and application, it can be difficult to strike the delicate balance between choosing the right core elements and ensuring that your welding stands the test of time. Hopefully, this article has given you the information you need to make an informed decision about which method and materials to use.
If you are still unsure, get in touch with us here at Lenoch Engineering. Our experienced, accredited and knowledgeable team can advise on the best course of action and help you choose the best materials for your project. We offer coded welding services for the production, repair, and modification of critical components.