What is cold welding?

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Cold welding is a bonding process where two items are combined into one by means of intense pressure that is applied by dies and rollers. As the name implies, this technique does not rely on heat to change the state of the items being turned on – these substances remain in a solid state throughout the procedure. Not all metals are ideal candidates for cold welding due to the oxygen content within their outer layers, and even after long brushing and cleaning, metals will not bond if one of them is not malleable. Likewise, if the two bonded parts are later exposed to an environment rich in oxygen or certain other reactive compounds, the cold weld will fail. Due to these limitations, the cold welding process is best suited for objects that will be deployed outside the Earth’s atmosphere, such as satellites or spacecraft.

Cold welding was first discovered by modern societies in the early 1940s and considered a new phenomenon, but this process has been around for thousands of years. It has been learned that two pieces of similar metals come together within a vacuum, provided they have clean, flat surfaces and a strong initial force can be applied. During the process, deformities occur on 60 to 80% of the bonding surface, and this allows pure, clean metals to come into contact. Permanent bonding then takes place at the atomic level, with welds much stronger than what could be accomplished by other means. Another advantage is that there is absolutely no intermediate material used as a type of solder, so as long as the oxides cannot reform on the surface of the metal, it should last for decades.

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From the early period of discovery, researchers have shown that cold welding can also be performed without excessive force. By applying less pressure over a longer period of time, similar results can be achieved. Another method is to increase the surface temperature of the two materials being bonded for a short time to accelerate the molecules.

The modern uses of cold welding are numerous, but it is still definitely considered a situational process due to the aforementioned limitations. The technique, however, makes it possible to work in many hostile environments that were previously impossible, such as welding underground pipelines that carry flammable gases. Another drawback is that because soldering occurs quickly and is considered permanent, it is very difficult to verify solder integrity, particularly on thicker metals.

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