What is solid-state welding?
There are various ways that you can join metals. However, welding has two broad categories; solid-state and fusion welding. The difference between these two categories lies on whether the process requires the melting of surfaces before welding them together.
Solid-state welding, as the name suggests, does not melt the surfaces but leaves them in the solid-state. Therefore, a welder has to be careful when applying heat on the surface to avoid melting it. Mostly, they have to accompany the heat with just a sufficient amount of pressure to create a strong bond.
different types of Solid-state Welding
In the world of welding, there is 12 different types of solid-state welding process. That 12 types of solid-state welding process are:
- Coextrusion Welding-CEW
- Cold Pressure Welding-CW
- Explosion Welding-EXW
- Diffusion Welding-DFW
- Electromagnetic Pulse Welding-EMPW
- Friction Welding-FRW
- Hot Pressure Welding-HPW
- Ultrasonic Welding-USW
- Hot Isostatic Pressure Welding-HPW
- Forge Welding-FOW
- Friction Stir Welding-FSW
- Roll Welding-ROW
Coextrusion welding involves the heating of surfaces, just like most of the other types of solid-state welding. However, there is one distinct difference that makes it unique. Here, you heat the whole of the surfaces, forcing them through an extrusion die. That is where the weld results from because the weld is unachievable without the application of pressure.
In this type of welding, you get to achieve a reliable weld because of how strong it turns out. Coextrusion welding has applied to the manufacturing industry. That is mainly in the automotive manufacture industry and even in ship making since it is effective
Cold pressure welding-CW
Cold welding requires that you use high pressure to create a weld. The high pressure can get easily found by using simple hand tools. In this case, you use this pressure at room temperature to create a bond. It first produces a coalescence, and at the end of it, you get to see some amount of deformation.
However, that can only be effective when you are trying to join thin materials. For thick materials, you need a press that can make it possible to exert enough pressure to make welding possible. Cold pressure welding has gotten used in several industries, especially in the manufacture of aerospace.
It is one of the few processes that do not require heat to work. However, the metal at the interface may appear to be molten after the process gets done. You can use different sources of heat to ensure that the melting process takes place. For example, plastic deformation is an excellent source of heat for the procedure.
Explosion welding has been instrumental in the manufacturing industry, especially in automotive engineering. Also, it has been essential in the repair of plug tubes on-site, especially, where it is tricky to apply the use of traditional means.
It is a rare welding type which does not require melting of surfaces. Here, you apply pressure at elevated temperatures.The temperature application produces coalescence at the surfaces of the joining materials. One of the best things about this process is that there is no deformation of the materials involved.
There are several applications that diffusion welding has contributed. Mostly, it has been instrumental in the joining of refractory metals in industries. The fact that this process does not lead to deformation makes it a perfect choice for people working in such sectors.
Electromagnetic pulse welding-EMPW
It is one of the most commonly used types of solid-state welding. Its application has been extensive in the automotive industry that involves the joining of either similar or dissimilar lightweight materials to create different things. It works perfectly with materials that have different physical and chemical attributes.
For example, you can use electromagnetic pulse welding if the materials you want to attach have different boiling points. Also, it is perfect for materials with differences in thermal conductivity and thermal expansion coefficients. It is an exciting type of welding because you get to do a lot of work within a short time since it is fast
Friction welding, as the name suggests, involves inducing friction by using two surfaces. What happens here is primarily mechanical inducement of surfaces to rub against each other and produce friction. The heat that results from the friction between the materials is what causes the coalescence that aids welding.
It is essential to monitor the level of heat achieved in this process. When there has been sufficient production of heat, you should stop the rotation and friction between surfaces. At this point, you can go ahead and exert adequate pressure to create a weld between the surfaces.
Hot pressure welding-HPW
The primary aim of this procedure is to produce deformation at the base metal. That happens by the application of heat and sufficient pressure on the joining materials. The deformation in this process is essential because it causes the oxide to crack and thus creates more areas of clean materials.
Experts advise that you undertake this process in closed doors. The primary aim of that is to achieve a vacuum or, to make it possible to use a shielding medium. Hot pressure welding has been useful in the manufacture of automotive, ships and aircraft.
It is the best for joining lightweight material. Remember, aerospace industries especially make use of such material. Planes and other flying equipment need to be light and not heavy.
Ultrasonic produces welds after you apply high-frequency vibrations to the surfaces you intend to bond. It is one of the best ways to weld and at the same time, the most economical. The mechanical vibrations frequencies range between 20 kHz and 40 kHz.
Ultrasonic can work well with the manufacture of various equipment. However, its most significant application has been in the automotive industry. There is a downside that relates to this type of welding. It is the fact that you cannot join a lot of materials at one go. You may require to do it in shifts, and that may be time-consuming.
Hot isostatic pressure welding-HPW
It is one of the easiest ways you can join two metals more so in industries. When using this type of welding, make you that you have sufficient heat. That means, it should not be too much such that it melts the surface and not too low that it doesn't serve its purpose well.
Also, you need some amount of pressure to work well with this type of welding. Remember, the pressure should also be in adequate amounts.
Forge welding is another interesting solid-state type of welding. Mainly, forge welding involves the use of heat in a forge to produce coalescence of the metals. Also, the heat should get accompanied by sufficient pressure to help create a strong bond.
It is one of the conventional solid-state welding types. Previously, welders used red heat to heat the joining surfaces and a traditional hammer to exert the required pressure on the surfaces. This technique proved useful because they were able to manufacture different kinds of items. However, it Is not of everyday use in the modern industries
Friction stir welding-FSW
Welding using this technique requires that you produce enough heat to run the process. Here, you need a rotating tool that rubs against a stationary surface. The purpose of this is to create friction and excitement that can run the welding process.
The rotating tool should rub on the surface until there is sufficient heat for the welding process. You should stop it as soon as there is enough because the idea here is not to melt the surfaces. You should do this process while applying some pressure.
Just like most of the processes here, roll welding requires heat and pressure to create bonds. However, when heating surfaces and applying pressure to them using this method, you need to ensure you have enough rolls. Besides, the rolls have to be sufficient to produce coalescence of the metals.
Coalescence gets achieved when diffusion takes place between the two faying surfaces. Roll welding has become widely used in several industries as a way of joining metals. However, it has contributed a massive role in the aerospace manufacturing.It works well with light metals.
Advantages of solid-state welding
- It leaves both surfaces with the same properties
- It is ideal for use with dissimilar items
- There is no need for using consumable elements
- It leaves the welded surface looking neat
- It is fast especially for professional welders and inexpensive
- It works well with materials of different densities