LASER WELD OVERLAY I CLADDING
This process brings the metal surface to a substantially higher temperature than in the heat treating process and results in a thin molten surface layer. Then, the desired amounts of additive elements are added into the molten Layer. The cladding material can be prelaid, powder bed, blown into the laser generated molten pool as a powder, or fed into the laser beam as a wire. Alternatively plasma clad layers or electroplated layers, which are often porous, can be consolidated by remoulding with a laser, with the future advantages noted under rapid surface quenching. It is also possible to heat the substrate with a laser and deposit by vapour deposition on that hot spot. The main features of the laser cladding are:
(A) Controlled dilution of the clad layer is possible.
(B) Very low HAZ, enables efficient utilisation of alloys.
(C) Hmogeneous, fine structures are produced in the clad layer.
(D) Very low surface variation and porosity.
(E) Good adherence, if melting points are similar and if the two materials are weldable.
Laser surface alloying is similar to cladding except that the depth of penetration into the substrate is increased and the quantity of coating material is reduced.
It is economical to lay high performance materials on to a component where these properties are needed and use a substrate material that is significantly less expensive to acquire and manufacture. Components like these are found in equipment such as oil field and industrial valves, pumps combustion engines (both piston and turbine type), all have precision components that must survive extreme environment