| 摘要 |
A process and an apparatus for diffusion bonding two elements together with the assistance of instant mechanical friction is disclosed in which the areas to be joined or the whole welding assembly are heated either by localized heating methods or furnace. A constant or a variable axial pressure is applied to bring the members into contact. The bonding stress produced by the applied axial pressure, constant or variable, is maintained below the compressive yield strength of the elements throughout the entire diffusion bonding temperature range. At different stages of the bonding process, instant in-situ friction treatments at the joint are conducted by means of introducing small scale relative movement between the contact surfaces of the elements. The instant in-situ friction treatment is only aimed to reduce oxidation and to overcome the oxide barrier at the joint interface to stimulate inter-diffusion and coalesence. Microscopic mixing and localized grain growth are also achieved at the joint during friction treatment. The combination of temperature, pressure, time and instant friction applied at the contact surfaces does not produce any significant macroscopic deformation of the elements. Addition of insert material at the joint interface is optional. |
