Kiinteähitsauksessa

Kiinteähitsauksessa, known in English as solid-state welding, is a group of welding processes that join materials without melting them. Instead, the materials are joined through pressure and/or friction at temperatures below their melting points. This method is particularly useful for joining dissimilar materials that have very different melting points or are prone to form brittle intermetallic compounds when melted.

The primary mechanism in solid-state welding involves bringing the surfaces of the materials into intimate contact, often under significant pressure. This pressure causes plastic deformation of the materials at the interface, breaking down any surface oxides or contaminants and allowing metal atoms from each surface to bond. Temperature can be used to enhance the process by reducing the material's strength and increasing its ductility, but it is not high enough to cause melting.

Common types of solid-state welding include friction welding, diffusion bonding, ultrasonic welding, and explosion welding. Friction welding uses rotational or translational motion to generate heat through friction, which then leads to a solid-state bond under pressure. Diffusion bonding relies on prolonged exposure to heat and pressure to allow atoms to diffuse across the interface and form a bond. Ultrasonic welding uses high-frequency vibrations and pressure to create a weld. Explosion welding utilizes the kinetic energy of a controlled explosion to force materials together at high velocity, creating a bond.

Solid-state welding processes offer several advantages, such as the ability to join a wide range of materials, including metals, ceramics, and polymers, as well as dissimilar combinations. They also produce joints with excellent mechanical properties, often comparable to or exceeding those of the base materials, and can maintain the integrity of sensitive microstructures or coatings. The absence of melting also means there is no solidification shrinkage, reducing the risk of defects like porosity or cracking.