Solid-state welding process
A solid-state welding process is a set of welding processes in which welding is performed with the application of pressure and at temperatures below the melting point of the parent metal. The filler material is not required in these processes.
Types of Solid-state welding process
- Cold welding,
- Diffusion welding(Bonding),
- Ultrasonic welding,
- Explosive welding,
- Friction welding and Inertia welding
- Forge welding
Cold welding process
Cold welding is a solid-state welding process wherein an external force is used at room temperature. Pressure causes substantial deformation in the weld.
when two surfaces are pressed together, the oxide film from the high spots fragments and the metal behind that suffer plastic formation; melt to metal contact occurs because of the fragmentation of oxide film.
any metal can be made to weld by shearing the two surfaces together at sufficiently high normal pressure.
Following types of materials can be welded by cold welding
- Cu and its alloys.
- Aluminium alloys.
- Pure aluminium
- Al to Cu.
- Ni to Fe, etc.
Joint design for Cold welding
Following types of joints are used by cold welding process,
Usually, butt cold welding is used extensively in the manufacture of aluminium wire and cable. The most common use is to join successive reels of wire for continuous drawing to smaller diameters.
Lap joints are used for sheet or foil joining, packing as well as electrical applications that cover large distribution transformers into small electronic devices.
Applications of cold welding
cold welding is a useful process where fusion welding is not possible or risky such as
- It is useful in welding metals in explosive areas,
- It is used to assemble small transistors where welding heat might cause damage
- It is used to join wires when they break during the drawing operation.
In addition, cold welding is used for cladding and joining many similar and dissimilar metals.
To be continued…