Titanium has many advantages, which is why it is often used in applications where metals like steel or aluminum were previously preferred. It has a greater strength-to-weight ratio than steel and is attractive for systems where minimizing weight, like race cars and space vehicles, is a premium objective. However, leveraging titanium’s positive attributes can be challenging.
Welding titanium tubes and pipes are among the most challenging types of metal bonding. This is due in large part to the fragility when the weld puddle is exposed to the elements. One of the best ways to avoid the negative consequences of exposure is to implement a gas-shielding welding technique like GTAW. There are best practices for TIG welding titanium that must be followed to ensure the level of purity required when working with this material.
TIG Welding Titanium Best Practices
Titanium is a strong metal; however, its tensile strength–approximately 140 MPa–is much lower than that of stainless steel–350 MPa. It compensates by being roughly half as dense: 4.51 g/cm3 for titanium and 7.8-8 g/cm3 for stainless steel. Titanium’s light weight and strength, resistance to cavitation, erosion, and corrosion, and biocompatibility make it a preferred choice for many critical applications such as invasive medical devices, high-speed automotives, and aerospace and military systems.
Welding titanium is complex and requires that the weld area be kept free of any contaminants. This and other essential best practices are listed below.
| DO’S AND DON’TS OF TIG WELDING TITANIUM | ||
| WHEN TIG WELDING TITANIUM | DO | DON’T |
| Allow air in the fusion zone | ✔ | |
| Use small nozzle | ✔ | |
| Use products powered by air | ✔ | |
| Use titanium filler rod | ✔ | |
| Use purge dam | ✔ | |
| Back shield weld puddle with argon | ✔ | |
As shown in the table above, every effort should be made to minimize or eliminate, if possible, any air from the area where melted titanium is present. This is best accomplished by combining several targeted activities. For example, using a small nozzle for backfilling the weld area increases the probability that the titanium will become brittle due to high temperature. Additionally, introducing air into the weld area should be avoided. This includes using air-powered tools that may blow away the gas coverage.
Gas Coverage Is Key to Welding Titanium
Exposure to gases such as nitrogen, hydrogen, and oxygen will result in contamination and a ruined weld. The severity of the damage and, consequently, acceptability can vary but can be estimated by observing the surface color after cooling, as the titanium weld color code below illustrates.
| TITANIUM WELD COLOR CODE | ||
| Acceptable | May be Rejected | Unacceptable |
| Bright SilverDark StrawLight Straw | PurpleBlueBlue & Yellow | Brushed WhiteGray Blue |
When TIG welding titanium, argon gas, which does not adversely interact with the metal, is used to provide coverage. A purge dam helps keep the area clean by forcing air out of the weld area and into the atmosphere.
Optimizing Your Titanium TIG Welding Process
Welding titanium requires the creation of high-quality welds, which is why the relatively slow GTAW process is often implemented. The precision of GTAW or TIG welding helps ensure the purity necessary for titanium welds. The best method for maximizing the precision of the TIG welding process while also protecting the welder and others from chemical exposure is to employ orbital welding for your titanium project.
Orbital welding gives welders and operators greater control over the TIG process. The ability to view the weld in higher dimension detail and adjust weld parameters as necessary, without the physical/dexterity demands of manual welding, enable much greater precision and the creation of pure, high-quality bonds. Fully leveraging the advantages of orbital welding for titanium GTAW necessitates that you utilize the best equipment and tools available.
Arc Machines, Inc. is an industry leader in developing advanced and high-quality welding equipment. For inquiries on how we can help you apply orbital welding for your TIG welding titanium projects, contact sales@arcmachines.com. For service inquiries, contact service@arcmachines.com. Contact us to learn more about custom orbital welding solutions.
