Small titanium components are commonly welded using the Gas Tungsten Arc Welding (GTAW) process.  While GTAW is highly flexible and can yield a high quality weld, it is also slow, requires a high degree of skill for manual welding, and can produce significant distortion due to the high welding heat input.   Edison Welding Institute (EWI) has been investigating alternatives to GTAW for welding large thin titanium structures.   This paper describes the results of work to evaluate Gas Metal Arc Welding (GMAW) for welding titanium sheet-metal components.   Thicknesses studied are 1.5 mm, consisting of fillet and butt joint configurations.  Research was conducted on process parameter settings, shielding requirements, weld quality evaluations, and mechanical properties of weld joints. 

GMAW has traditionally been applied to “non-critical” applications where productivity is a primary concern and weld quality and properties are of less importance.  Modern GMAW power-source control technology offers increased precision to allow the process to be contemplated for quality-critical applications.  This work investigated two alternative GMAW processes: pulsed-current GMAW and reciprocating wire feed GMAW.  Each type offers distinct advantages for particular thin titanium applications. 

A significant challenge for titanium GMAW is maintaining good arc stability, which is necessary for achieving adequate weld bead shape, weld fusion, and avoiding spatter.  Welding process parameters and consumables must be carefully selected to produce precise deposits with no spatter.  Evaluation of arc stability and metal transfer was done through the use of a high speed data-acquisition system, allowing the synchronized capture of welding process parameters and high-speed video. 

Another important consideration for welding large titanium sheet-metal components is inert gas shielding.  Several methods of supplying shielding gas coverage for both the weld bead and the back-side of the joint are being evaluated.  The goal is to achieve adequate coverage while minimizing set-up and purge time.