Welding titanium is not rocket science, as most people tend to see it. Due to some subtle differences, however, a trained eye or knowledge of a few of the basics could be the difference between pass and fail. The basic steps for titanium welding are quite similar to welding other metals, and only require different amounts of focus. Whereas welding steel might be 30% preparation and 70% actual welding, titanium welding is essentially just the opposite: 70% preparation and 30% welding time.
When it comes right down to the actual process of "running the bead," as they say in the trade, welding titanium differs little from the welding of any other ferrous metal such as steel or stainless steel. As long as some key elements are controlled, welding titanium can be done by almost any experienced welder.
Some of the most important steps take place before and after the actual welding occurs. Eliminating the impurities on the material is first and foremost. Clean material is absolutely crucial to the overall integrity of the titanium weld. This can be achieved through chemical cleaning. Even microscopic bits left behind from a grinding disk, or the oxidized surface itself must be removed. The natural oils on the skin can even contaminate the filler rod. All of these surfaces must be as clean as possible.
Once all of the surface impurities are eliminated, the next factor to consider is the atmosphere, since the actual air around the titanium weld can cause problems. There are several ways to overcome this dilemma. Specialized equipment is available for welding titanium, depending on the available budget. Trailing cups can work for short jobs; however, for production, a small investment of a vacuum-controlled chamber might be in order.
Yes, a chamber is as expensive as it sounds, but it is a worthwhile consideration. The reason: while welding titanium, heat naturally spreads into the surrounding material. This is known as the heat affected zone or HAZ. Oxygen can and will react to titanium at temperatures just below its melting point, and therefore cannot come into contact with the HAZ while it is still above a certain temperature. The entire area of the HAZ must be constantly purged with pure argon until the surface temperature no longer reacts to the oxygen in the atmosphere.
Controlling these key variables is essential to successfully welding titanium. It is important to note that welding titanium is considered a very expensive process; therefore, it is not recommended for anyone who may still be learning the art of welding.