High power diode laser welding of a titanium alloy

Abstract

The commercial availability of direct diode lasers having output powers in excess of 1 kW has seen the development of a number of manufacturing applications - surface hardening of steel, welding of plastics and surface cladding to name but three. Whilst diode lasers have many attractive features, their inability to be focussed to a small spot generally means that welding is achieved purely by conduction. Generally, the power density is not sufficient to produce a plasma or “keyhole” weld, though this has been shown to be possible with certain diode laser configurations and materials.Despite most welds being conduction limited, a variety of metals have been welded with diode lasers and there are many commercial applications in which high integrity joints in sheet material are required. An example of this type of application is the gas turbine engine; fabricated structures are required in materials such as titanium that can be considered difficult to join. The current work considers process conditions and metallurgical aspects relating to the welding of a titanium alloy sheet. Process windows are suggested which consider both the speed of processing and metallurgical quality of the resulting weld.The commercial availability of direct diode lasers having output powers in excess of 1 kW has seen the development of a number of manufacturing applications - surface hardening of steel, welding of plastics and surface cladding to name but three. Whilst diode lasers have many attractive features, their inability to be focussed to a small spot generally means that welding is achieved purely by conduction. Generally, the power density is not sufficient to produce a plasma or “keyhole” weld, though this has been shown to be possible with certain diode laser configurations and materials.Despite most welds being conduction limited, a variety of metals have been welded with diode lasers and there are many commercial applications in which high integrity joints in sheet material are required. An example of this type of application is the gas turbine engine; fabricated structures are required in materials such as titanium that can be considered difficult to join. The current work considers process conditions and m...