TWI has pioneered a new ‘invisible weld’ process for Linear Friction Welding (LFW) that can blur evidence of the join line when welding titanium alloy.
TWI pioneers ‘invisible weld’ process
LFW is a solid state joining process that is used for several niche aerospace applications. The process involves pushing two parts together, with one oscillating at a high speed, to create friction that heats the metals to a high enough temperature to join them together.
Once cooled, the LFW process creates a forged-quality weld, which provides a number of advantages over other processes, including imperfections and impurities being removed from the joint into a flash. LFW is also a very fast process, taking as little as one second to create a weld, and requires very little preparation of the surfaces before the process begins.
For all of the evident advantages, LFW still creates a change in the microstructure that can be seen along the line of the weld. However, TWI has created a post-weld heat treatment process for titanium alloys that can effectively remove this line by restoring the microstructure of the parent metal, bringing back its mechanical properties.
While LFW already requires no consumables, creates no harmful fumes and, as a solid-state process, avoids potential issues associated with solidification, the new ‘invisible weld’ method looks to improve on this impressive list of benefits.
LFW is already used in the aerospace industry on critical engine compressor components, and this improvement to the process should further help save on material, manufacturing costs, and lead times by allowing the design freedom to place a weld line regardless of the load condition for any given component.
TWI is a world leading research and technology organisation with a focus on materials, engineering and manufacturing.