21.4 Welding Reactive Metals
David Colameco, M.Ed.
Reactive metals are metals that, when heated to elevated temperatures, react with the oxygen and nitrogen. The heat of welding raises the temperature of the weld and adjacent base material above the reaction temperature. Reactive metals are zirconium, titanium, and beryllium.
As a welder starting to learn the trade you will not be welding on these metals, however it is important to know that they exist because these metals are used and welded on in Washington State. Due to the increased cost of the base materials and their use in critical applications, most welding will be performed with automatic processes. Does your program offer classes on robots? Welding processes are automated with robotics in many industries. If you are interested in robotics, look into your school’s course offerings to see if an introductory class to robotics you might like is offered in a mechatronics program.
Development of welding reactive metals
Reactive metals are just that, metals that react when welding. These metals react with the gasses in the atmosphere at elevated temperatures in a negative way leading to contamination of your weld and/or heavy oxidation of the nearby base materials. To avoid this contamination, special care is needed in applying protective shielding gasses.
If welding reactive metals requires more preparation and more care when welding, why weld them? The material properties of these metals are needed for the applications of aerospace, nuclear, and other demanding in-service environments where the extra cost of fabrication is required.
Basics of welding reactive metals
All three reactive metals are welded. Beryllium is a dangerous metal if inhaled and should not be used in fabrications unless adequate safety precautions are taken.
Due to the reactive nature of these metals, cleanliness and the application of inert shielding gasses are even more important than stainless steel welding. If you have welded on low carbon steel and then switched to stainless steel, then you know the importance of cleanliness and shielding gas when welding. Reactive metals are another step above stainless steel in terms of both cleanliness and shielding gasses.
GTAW is used to weld zirconium and titanium. GMAW can be used to weld titanium. Other processes that are beyond the scope of this text are also used, such as laser beam welding (LBW). When GTAW and GMAW are used to weld titanium, argon is normally used. Helium and mixtures of argon and helium can be used but the price of helium has increased significantly in the 2020s resulting in its decreased use. As with all welding, but especially more expensive metals, welders are encouraged to test their machine settings on a scrap piece of material prior to production welding. This is especially important with reactive metals to help ensure quality welds.
Due to the low thermal conductivity of titanium, you will notice that the weld pool will be larger than with metals t