We’ll be publishing a series of posts about different metals to provide readers with information regarding the properties of each metal and offer some general tips on how to weld with each metal successfully. First up in the series…TITANIUM!
Titanium is the ninth most abundant element in the Earth’s crust and the fourth most commonly used structural metal. The lightweight metal has a high strength-to-density ratio and it’s as strong as steel but less than half its weight. Titanium is a very corrosion resistant metal that is able to withstand extreme temperatures. In fact, Titanium’s melting point is 3,135 degrees F°; approximately 400 F° above the melting point of steel and 2000 F° above that of aluminum.
These qualities make titanium a popular choice for applications in the aerospace and defense industries (think Navy ships, for example), however, titanium’s extraordinary corrosion resistance makes it a reliable, cost-effective material for use in many other applications as well. It looks nice, but, can have a reputation for being difficult to weld because of its high sensitivity to oxygen, moisture, grease, and other metals, leading to brittle welds. With the proper equipment from Arc-Zone.com and the following guidelines, you’ll have what you need to weld titanium successfully!
PREPARING YOUR WELDING ENVIRONMENT
Titanium is a highly sensitive metal and its fabrication demands attention to cleanliness not only of the base metal, but of the shop as well. We suggest setting aside a separate area of your shop to be used strictly for titanium. Make sure the area is free of drafts, moisture, dust, grease and other contaminants. Ideally, a low dew point should be maintained as well.
PREPARING MATERIAL TO BE WELDED
Prepare the area to be welded THOUROUGHLY! Prep work should ensure that joint surfaces are smooth, clean and completely free of contamination. Use only a stainless steel brush that has been only used on titanium to prevent cross contamination from other metals.
Many fabricators use acetone as a cleaning agent, however, Arc-Zone.com recommends EZ WipesTM, specialized, pre-saturated lint-free fabric wipes that come in a convenient shop pack. One side is abrasive to loosen dried contaminates and the other side is smooth to reveal a cleaner polished surface. This is an acetone free cleaning agent, safe, easy to use, and can be disposed of in the regular trash. Use lint-free gloves when using the cleaning agent.
As mentioned before, titanium is very sensitive to oxygen contamination, so one important factor is maintaining the proper shield gas coverage, and allowing the weld to cool without letting oxygen in. Argon is the shield gas of choice for titanium welding. The argon MUST be 99.99 percent pure; otherwise it can lead to some yellow-straw discoloration and a brittle weld.
Be sure to adjust the flow rate for optimum coverage and torch cooling without creating turbulence.
Use a 1″ (25.4mm) large nozzle with a gas lens or gas flow straightener.
Titanium is sometimes welded in a purge chamber to surround the weld with shielding gas. However, this is not always a practical or economically viable solution.
Trailing shields attach to the trailing side of your TIG torch to supply additional shielding and protect the molten weld puddle. Generally trailing shields require a secondary gas source and are often custom-made for a particular torch and application; however there are some good off-the-shelf options available as well.
Arc-Zone carries a complete line of high-performance engineered trail shields, as well as other trailing devices.
A low-cost, high-quality alternative to trail cups and other purge welding devices is Arc-Zone’s MonsterTM Nozzle, a No.16 (1″ / 25.4mm) orifice, 1-1/8″ (28.5mm) long, constructed of non-conductive ceramic with fine and coarse replaceable screens secured by a stainless steel snap ring.
Always use a backup shield device to protect the root side of the weld.