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Why is pressure used in solid-phase welding processes?
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welding
Shielded metal arc welding.
In solid-phase welding, pressure is a fundamental requirement because these processes join materials without melting the base metal or using filler material. By applying sufficient force, the surfaces are brought into intimate contact, facilitating coalescence.1
The specific role of pressure varies by technique:
- Cold Welding: Pressure is used to induce significant plastic deformation—typically 35 to 90 percent—at the joint interface to achieve a bond without the application of external heat.2
- Diffusion Bonding: Pressure is applied at elevated temperatures for an extended period to promote atomic diffusion across the interface. In this process, pressure is generally kept low (causing less than 5 percent deformation) to allow for the joining of finished machine parts without altering their dimensions.3
In all solid-phase processes, pressure serves as the primary mechanism to overcome surface irregularities and achieve the atomic proximity necessary for a strong, unified joint.1