Welding is a method or technique of joining metallic parts usually by applying heat. This technique was discovered in order to transform metals into different shapes. Nowadays, the process of welding is used in different fields such as in iron-making techniques, making cast iron, jewelers, and blacksmith uses a lot of welding procedures.
Modern fusion welding processes are required in the complex process of joining large steel plates. Gas welding, arc welding, and resistance welding become very popular in the 19th century. Welding processes become popular since World War I.
How Does the Process of Welding Works?
The Process of Welding Involves Joining Metals
Unlike brazing and soldering, welding is a high heat process that melts the base material entirely. It is possible only with the addition of filler material.
The Welding Methods are Used for Joining Plastics
In the case of Plastics welding, heat is used to join materials. By creating fusion, the plastics can be joined, these processes can be of two types external or internal heating methods.
The Welding Methods are Used for Joining Woods
In the process of Wood Welding, the heat gets generated from friction to join the materials. A linear friction movement creates heat to bond the workpieces together.
The type of metals used in the process of welding matters the most. This whole concept depends upon the nature of the metal used. There are different varieties of welding joints and methods of welding.
What are the Different Types of Welding Methods?
There are different methods of Welding Process such as
This method has a varied number of common manual, semi-automatic, and automatic processes. There are various types including metal inert gas (MIG) welding, stick welding, tungsten inert gas (TIG) welding, gas welding, metal active gas (MAG) welding, flux-cored arc welding (FCAW), gas metal arc welding (GMAW), submerged arc welding (SAW), shielded metal arc welding (SMAW) and plasma arc welding.
These methods are used for joining metals including stainless steel, aluminum, nickel and copper alloys, cobalt, and titanium. The Arc welding methods are primarily used in industries such as automotive, oil&gas, etc.
In the case of Friction welding techniques, the materials are joined by using mechanical friction. This method is used in joining different welding materials including steel, aluminum, or even wood.
This particular method of welding doesn’t require the use of filler metals, flux, or shielding gas. It is used in aerospace applications on a large scale because it is an ideal method for joining ‘non-weldable‘ or light-weight aluminum alloys.
Electron Beam Methods:
With this method, there is are a varied beam of high-velocity electrons that are used to join materials. The kinetic energy of the electrons gets transformed into heat that creates a simultaneous impact on the workpieces that causes the materials to melt together.
EBW has been used to join thick sections also. It is applied in a number of industries from aerospace to nuclear power and automotive to rail.
Laser methods, Resistance, Spot Welding ad Seam Weldings are also very popular
There is a large number of fusion techniques that come into existence with the various usage of iron. This process gets invented when people try to form a big piece of iron by joining small pieces together. Firstly, the pieces were given a shape then they got heated to a welding temperature in a forge and later they were pressed together or hammered to form.
The best example is a Damascus sword which has thin wrought iron bars that were hammered doubled back on themselves and then rehammered to produce a forged weld. The many times this process gets repeated the sword becomes tougher and stronger. This process was widely used in the middle ages. Mostly cannons were built by welding together several iron bands. The bolts were tipped with steel fired from crossbows and were fabricated by forge welding.
The blacksmith used forge welding a lot and in modern times usually, chains are made with the technique of forge welding. The process of welding is an operation where two pieces of metals are joined together by the usage of heat or pressure or both. Forge welding is usually on metal, especially iron. This is one of the oldest and popular forms of welding.
Arc welding can be used in alternative or direct currents. It applies consumable or non-consumable electrodes coated in flux. In the process of arc welding, the temperature can increase as high as 6,500 degrees Fahrenheit.
Mostly the process of arc welding is widely used in different industries like steel erection, heavy equipment repair, pipeline welding, and many major construction projects. Without discussing the merits and demerits of arc welding we cannot argue how this process of welding is better than the other processes. So let’s discuss in brief the advantages and disadvantages:
The major advantages of arc welding that lead the different industries to use this process because it is not costly. The process usually requires fewer pieces of equipment. This works on dirty metals and is easy to move. Under arc welding, the shielding of gas is not required and the process can be initiated and completed during rain or water and no need to worry about spatter.
The process has fewer disadvantages. Highly skilled workers are needed. Also, it is very tough to use arc welding on thin materials.
There are different types of Arc Welding process. There are 30 different types of welding processes existence, ranging from simple oxy-fuel to high-tech processes such as laser beam welding. However, there are four important welding methods used commonly, and they are MIG(Mig Welders), TIG (Tig Welders 2020), Stick, and Flux- Cored arc welding.
One of the methods of welding is known as gas welding or thermochemical processes. Earlier it was a popular method but now it is specifically used in a specialized field of sheet fabrication, only used by skilled workers. This is a fusion process where heat is supplied by burning acetylene in oxygen.
So to provide an intense and controlled flame. Metal is added to the joint in the form of cold filler wire. A neutral or reducing flame is generally desirable to prevent base-metal oxidation. By deft craftsmanship, very good welds can be produced, but welding speeds are very low. Fluxes aid in preventing oxide contamination of the joint.
There is another popular form of the thermochemical process is aluminothermic (thermite) joining. This has been applied for both ferrous and nonferrous metals but mostly used in ferrous metals. The thermochemical process is appropriate to join large chunks of metals and compact cross-sections like rectangles and rounds shaped metals.
Resistance welding is used where metals are joined by the application of pressure and passing currents for a long period of time so that metals can be joined together.
The major advantage of this process is that there are no other materials needed to join the metals unlike other former processes of welding, this makes the process highly cost-effective and apt for many small scale industries.
There are different variations of resistance welding such as spot and seam, projection, flash, and upset welding. These processes use varied types and shapes of weld electrodes to apply the pressure and conduct the current between the metals.
Resistance welding machines are widely used in the automotive and aerospace industries. These machines are automatic and can be controlled easily thus result in steady production.
Types of Resistance Welding Applications:
Spot Welding and Seam Welding
In the process of Resistance Spot Welding, workers weld the pieces of metals using heat generated by resistance to the flow of welding current between the faying surfaces, as well as force to push the workpieces together, applied over a defined period of time.
Resistance Spot Welding uses the face geometries of the welding electrodes themselves to focus the welding current at the desired weld location, as well as to apply force to the workpieces.
Like other Resistance Welding Processes, Flash Welding uses heat generated by resistance to the flow of welding current, as well as force to push the workpieces together, applied over a defined period of time. Flash Welding is a Resistance Welding Process that generates resistance using flashing action.
Like other Resistance Welding Processes, Upset Welding uses heat generated by resistance to the flow of welding current, as well as force to push the workpieces together, applied over a defined period of time.
Electron Beam (EB) Welding is widely used for applications containing refractory alloys and dissimilar materials. There are several advantages of EB Welding technology that include a high power density with very low overall heat input and that results in minimum distortion.
The EB welded parts simply needs a minimum of post-weld machining and heat treatment, and opposite to other welding processes, EB requires no shielding gases. The quality and standard of the weld are exceptional and the process is highly effective (typically 95%), carefully controlled and fully automated.
In a layman’s language, Electron beam (EB) welding is the process of fusioning electrons that are generated by an electron gun and accelerated to high speeds using electrical fields. This high-speed stream of electrons is tightly focused using magnetic fields and applied to the materials to be joined. The beam of electrons creates kinetic heat as it impacts with the workpieces, causing them to melt and bond together.
Advantages of Electron-beam welding
- By using this method workers can weld thin foils to thick sections (greater than 2.5″ depth-of penetration)
- This welding method is unique. Multi-axis EB control
- The process has a high ratio of depth-to-width
- With the usage of EB Welding, one can achieve maximum penetration with minimal distortion
- This has exceptional weld strength
- It has an inert atmosphere (vacuum)
- This method has high precision and repeatability with virtually 0% scrap
The process of EB welding undoubtedly is highly automated and controllable, while also being excellent for joining materials, such as refractory or dissimilar metals, as these cannot be weldable with conventional processes.
Cold welding (also known as cold pressure welding and contact welding) is a process of welding that uses pressure to join two metals or materials. This advanced process is also called solid-state diffusion and it applies pressure to create welds.
In simple terminology, when two materials are pressed together, they generally do not weld to each other. Cold welding prepares the metals before they are welded. The preparation process involves cleaning or brushing the metals to such an extent that the top oxide or barrier layer is removed.
Cold welding is a joining technique that has some drawbacks as well. The joint can fail tremendously in a reactive environment or a high oxygen environment. This method is excellent for buried pipes and for components deployed in spaces where there is no risk of oxygen contact. But the utmost essential requirements of the cold welding is that the surfaces need to be brushed and cleaned effectively.
So we have to be very cautious to make sure that the outer layer of any one of the components should not have high oxygen content, otherwise the adhesion is unlikely to occur. Another critical factor is the malleability of the metals used. At least out of two, one metal should be malleable.
Friction welding, the most popularly known as spin welding. It is a fully controlled mechanical process for joining SIMILAR or DISSIMILAR (Bi-Metal) combinations of materials or metals. The main aim of spin or friction welding is to have a 100% weld throughout the full joint interface.
Before discussing the varied types of friction weldings, let’s try to understand the definition and process of friction welding and how it is different. Solid-state welding is a type of welding process that doesn’t apply external heat to weld the materials.
External pressure is applied to a solid-state to form the weld. In the process of friction welding, the workpieces to be joined rotate relative to the other. This movement of materials helps in creating friction, which heats the materials at the contact surfaces. By applying a high-pressure force until the welding cycle is complete, workers weld the materials together.
Friction welding can be used to join a variety of metal (such as steel and aluminum) bars and tubes exceeding 100 mm in diameter.
Different varieties of Friction Welding:
- Inertia Friction Welding
- Direct Drive Friction Welding
- Linear Friction Welding
- Friction Stir Welding (FSW)
- Orbital Friction Welding
Laser beam welding (LBW) is a welding process that is used in industries to join pieces of metal or materials by using a laser. The beam of the laser provides a concentrated heat source, allowing for narrow, deep welds and high welding rates. This popular welding process is frequently used in high volume applications in the automotive and aerospace industries.
The whole concept of laser welding is based on a keyhole or penetration mode welding. This process of welding method is applied when there are materials or components that need to be joined with high welding speeds, thin and small weld seams, and low thermal distortion. In the modern industrialization era, laser welding is very much effective and commonly used.
The reason why it is so popular is that because of its high welding speeds, excellent automatic operation, and the possibility to control the quality online during the process.
With the help of laser welding, the welding of non-porous seams in medicines is possible, it helps in spot welding in the fields of electronics, jewelry, mold making, and complete car making in automobile industries.
Major Key Benefits of Laser Welding
The best manufacturing companies around the globe use this laser welding, we have got major 5 benefits of the methods:
1) High level of precision: Laser welding offers great accuracy and control. This technology is so precise as it can weld the smallest of parts together, without causing any damage to them.
2) Laser technology can join the most complicated weld materials.
3) This method has low heat applications that minimize the distortion of the materials in the welding process., it’s a contact-free application that results in very low thermal strains.
4) The welding done by the laser method is very durable and of high strength.
5) Repeatable and consistent welding methods available in the modern era.
In the case of diffusion bonding, the layers of sheet metals are joined together. There are thin sheets of metals that are packed together in a vacuum, then applying the heat on the 50-80% of the base material’s melting point while pressure is applied.
This method of heating and application of pressure yield a few of the electrons from each sheet of metal to migrate to its neighboring sheet until the stack is internally joined together. This generates a strong material, and joint, with the full properties of the parent metal remain intact.
There are several features of Diffuson methods
- This method is electrically conductive
- The result leads to the high fracture toughness of the materials
- Small bonding frames
- Hermetic sealing
- It leads to very stable post-bond alignment
- This method has No contamination, very safe and reliable
- Also, it has, No or very little deformation
Another most widely used method of welding is “ultrasonic welding”.It is a welding method where the thermoplastics are joined through the use of heat generated from high-frequency mechanical motion. This process is possible by converting high-frequency electrical energy into high-frequency mechanical motion. That mechanical motion also comes with additional applied force, generates frictional heat at the plastic materials joining surfaces so it melts and creates a stronger molecular bond between the parts.
This method of welding has several advantages. There are many favorable factors like this process is quite fast, clean, efficient, and repeatable, as a result, the outcome it produces is strong and durable, also it consumes very less amount of energy.
There is no need for solvents, adhesives, mechanical fasteners, or external heat. The outputs are really durable and clean. There are many difficult materials that can be assembled or treated ultrasonically. Part assemblies are also possible.
This process is very fast due to the rapid dissipation of heat. This method of welding is a very low-cost investment compared to other methods of welding. The high reliability, long life, and consistent, repeatable performance, makes ultrasonic welding the most preferred form of welding.
Ultrasonic welding is widely used in areas like automotive, medical, electrical and electronic, communications, appliances, consumer products, toys, textile, and packaging industries. It is an economical process for factories that optimizes the cost of production.
Explosive welding is very much different from the other methods of welding. It does not involve the joining of material by melting them. In simple terms an explosive weld is achieved by impelling the cladding plate against the substrate plate material using the considerable energy from an explosive discharge, resulting in a high energy rate impact.
The high interfacial pressure at the point of contact (or collision front) between the cladding plate and the substrate plate must be greater than the yield strength of both materials, to permit plastic deformation within the surface layers to occur.
A jet of highly softened metal is formed that creates a bond between the two materials. Because bonding occurs in the solid phase, it is possible to weld metals with different melting points and some of the common clad layers deposited onto steel plates are aluminum, copper, bronze, titanium, Monel, nickel alloys, and zirconium.
Alternatively, explosive welding can be used to repair or plug tubes in heat exchangers on-site, where conventional welding methods are difficult to use.
Weldability of metals
The process of welding is very complicated. It combines the science of electricity (aside from oxyfuel welding), heat, metallurgy, different states of matter, and oxidation.
This signifies that there can be many complications arrives when it comes to weld two distinctive materials. The secret to success is by choosing a metal that is easily weldable and does not require many extra pre-weld and post-weld operations to prevent weld failure.
Few of the best and popular metals for welding are:
- Low Carbon Mild Steel
- Stainless Steel
- Other Metals
WELDABILITY OF STEEL
One of the most common popular welding materials is Steel. It is popularly used by many industries because of its strength and versatility. It is widely used in all types of structural construction with detailed designs, steel is recognized by various.