Rapid Repairs: Surface Preparation of Ti-3 Al-2.5V Alloy Tubes by Fiber Laser and Welding

摘要

Titanium alloys are used extensively in aerospace applications mainly due to their superior strength to weight ratio. Different grades of titanium alloys are used for different applications. The alloy Ti-3Al-2.5V is used to make seamless tubes, used in hydraulic systems of aircrafts for its excellent cold formability. Welding of these tubes with other components is indispensable for installing hydraulic systems. Normally fusion welding process, namely Gas Tungsten Arc Welding Process (GTAW) is undertaken to join theses components. Different sized tubes are required to be welded with different end fittings. Production of high quality welds in titanium alloys requires meticulous pre-weld surface preparation of the work-pieces. Conventionally such preparation procedures are chemically based, where the entire component is cleaned by chemical etching in toxic chemicals like hydrofluoric acid, nitric acid etc. This process removes some material from the surface along with the contaminant, exposing fresh material for joining purpose. This method is presently adopted by NAVAIR to clean the tubes prior to welding. However these chemicals are hazardous and environmentally malign. Handling of these chemicals, disposal and safety of individuals is also of concern. The footprint of these cleaning systems is also too large. The main objective of this project is to develop an environmentally friendly compact titanium alloy tube laser cleaning and welding system for NAVAIR use.