Laser Processing of Titanium
Brian Victor | Applications Engineer, Laser Processing
Fuel efficiency is driving the use of titanium and other light-weight materials in new aerospace applications. Due to fluctuating titanium costs and stricter buy-to-fly requirements, alternatives to forged or billet-machined components are becoming more attractive. Alternatives such as laser welding and laser additive manufacturing (LAM) can produce near-net-shape titanium components with reduced buy-to-fly ratios.
Titanium laser welding can be conducted autogenously or with filler addition. Autogenous laser welding is a high productivity process that offers low heat input and low distortion. Travel speeds in excess of 120 ipm (3 m/min) are possible for welding butt joints of 0.25 in. (6.35 mm) or greater. Autogenous laser welding can produce acceptable full-penetration welds per AWS D17.1 Class A specification. Figure 1 is a cross section of an autogenous laser weld on titanium.
If additional material is needed to fill a gap or provide additional weld reinforcement, other laser welding processes such as hybrid laser arc welding (HLAW) or laser welding with cold-wire addition can be used. The laser with cold wire process adds a solid filler wire into the laser weld pool. The HLAW process combines laser welding and gas metal arc welding (GMAW) in the same weld pool. Figure 2 is a cross section of a hybrid weld on grade 5 titanium (Ti-6Al-4V). By using high-productivity welding processes such as HLAW or autogenous laser welding, titanium structures can be fabricated from sheet or plate materials rather than machined from a large billet, forging, or casting.
Another technique for reducing material waste and improving the buy-to-fly ratio is to use an additive manufacturing process. Laser additive manufacturing (LAM) can be used to produce new net-shape structures, to build-up features and bosses on existing parts, or to repair local damage and wear on overhauled components. LAM encompasses multiple processes that use a laser beam to consolidate added material to produce near-net-shape components. Some LAM techniques that are applicable for titanium components include coaxial or off-axis powder feed, off-axis wire feed, and powder bed consolidation.
As titanium becomes more prevalent in aerospace components, high-productivity fabrication processes such as laser welding and LAM can be used to reduce material waste and improve buy-to-fly ratios compared to traditional forging and billet-machining processes. These advanced laser processing techniques can be used to construct airframes and engine components, repair blade and tip wear, manufacture net-shape components, and provide high-quality low-cost solutions for the next generation aerospace industry.