Titanium is a highly reactive metal, which is why, in the past, people only welded it in tightly sealed chambers. However, titanium is not as hard to weld as people think. With proper gas shielding and preventative measures, you can easily undertake the job. In this article, we will tell you how to weld titanium.
Titanium has a few properties that play a critical role in the welding process.
- It has a lower density than most metals
- It is not as elastic as other metals
- Titanium has a higher melting point than most other metals used in welding
- It is a readily reactive material and gets contaminated easily
- It is not as ductile as stainless steel
A proper titanium weld will look like frozen mercury – it will be shiny and reflective. To ensure that you produce a good quality weld, you should first follow a few steps to prepare the weld surface for the procedure.
Clean the Surface
We advise you to prep your surface before all weld jobs. However, with titanium, you need to be particularly careful. The cleaner your surface is, the stronger the joint will be. Oil, dust, grime, rust, cutting fluid, and paint can result in a brittle joint, which counts as a weld failure.
To ensure a durable and successful weld, follow the three C’s:
- Clean surface
- Clean workspace
- Clean filler rod
If even one of these surfaces is not clean, you can easily end up contaminating your workpiece. To remove all unwanted particles from the surface, we suggest that you use a chemical cleaner specifically designed for titanium.
For the work surface, use a steam cleaner and a dilute solution of sodium hydroxide to wipe away all contaminants. Then, use a hot air blower to remove all moisture from the workspace.
Do not use a hot air blower on any flammable chemical solvent. You need to make sure that the chemical cleaner you use to clean the workpiece is not flammable.
Clean all the equipment and wipe it dry before use. You can use the solution you used for the work station for the tools as well.
Titanium does not react well to chlorine, so double-check the cleaner to ascertain that it is not chlorine-based. Rubber gloves also contain chlorine, so instead, use either plastic or cotton gloves.
Choose a Shielding Gas
Since titanium reacts readily with air, oil, dirt, moisture, and other metals to form brittle compounds, using the right shield gas is essential when you’re looking to ensure that you end up with a strong weld. Usually, most welders use 99.999% pure Argon for the process. Only really pure Argon and Helium provide optimal protection from the atmosphere.
When you buy the shield gas for your welding project, make sure that you only get this gas from trusted suppliers. Even if the Argon is slightly less pure than required, it can result in discoloration. You will end up with a yellowish tinged weld, which is not something that you want to happen. Impure gas or incomplete coverage can also cause blue tinting and mottling.
With titanium, you need to ascertain that not only the front but also the back is kept protected from the atmosphere. Any area that is heat affected will have an adverse reaction if it comes in contact with oxygen.
For smaller parts, you can use enclosed compartments made out of glove boxes that are filled with shielding gas. You can even use specially made polyethylene purge gas chambers combined with a purge monitor. With them, you can verify that the chamber has enough Argon to provide optimal protection.
If you’re looking to have an ideal level of coverage while you’re welding, here are three steps that you need to follow:
- Primary Shielding – it is usually built in the welding torch and provides primary coverage necessary for protecting the molten weld puddle. You can use a standard, water-cooled torch that’s equipped with a ceramic cup and gas lenses. We suggest that you choose a torch with a broader cup for the best coverage.
- Secondary Shielding – Trailing shields provide secondary protection. They are attached to the end of most welding torches and guarantee that all heat-affected areas are kept safe from contamination.
- Backup Shielding – These devices look similar to trailing shields and serve virtually the same function. They are either handheld devices or are taped into position. They rarely ever come pre-fit into the welding torch.
Selecting the Right Filler Wire
When choosing the filler metal to weld titanium and its alloys, we suggest you choose a filler wire that primarily holds the same properties as the base material. You can also select a wire that is categorized in a strength level that’s one grade below the base metal. In some situations, the welder may even use a different category of filler wire altogether.
Your choice of filler wire will depend on the properties and the combination of the joint. To improve joint ductility:
- When welding unalloyed titanium of higher strength, use a filler metal that is lower in yield strength of the base.
- You can use unalloyed filler material when welding titanium from the Ti-5A1-2.5Sn and Ti-6A1-4V classifications.
- Another option is filler metal with lower percentages of oxygen, nitrogen, hydrogen, carbon, and other alloying contents than the base metal.
Usable Welding Processes
When welding titanium and titanium alloys, you can use any of the following welding procedures:
- (EBW) Electron-beam welding
- (GTAW) Gas-tungsten arc welding or (TIG) Tungsten Inert Gas Welding
- (RW) Resistance welding
- (LBW) Laser-beam welding
- (PAW) Plasma arc welding
- (GMAW) Gas-metal arc welding or (MIG) Metal Inert Gas
- (FRW) Friction welding
Electron Beam Welding
This is a fusion process that utilizes a high-velocity electron beam to join two metals together. When the beam comes in contact with the metal pieces, it generates intense heat. The two plates melt and fuse to form a solid joint. Aerospace and aircraft production industries utilize electron beam welding because of the durability of the joints produced.
You can use the electron beam welding procedure for plates ranging from 6mm to 76mm and more. The process produces high-quality welds with low contamination levels as the process takes place in a high vacuum atmosphere.
Tungsten Inert Gas / GTAW
TIG or GTA welding processes use a non-consumable tungsten electrode that transfers current to the welding arc. Shielding gas is used to protect the weld puddle from external contamination, which can result in weak and low-quality welds. In the process, you need a filler metal or wire for the weld joint.
It is a widely used process for welding titanium and its alloys. You can use TIG without a filler material for square butt groove joints on base metals up to 2.5 mm in thickness. For thicker sheets, you need to use a filler metal to guarantee that the resultant weld joint is durable.
Resistance Welding (RW)
Resistance Welding is a thermo-electric procedure. It joins two pieces of metal together by passing a controlled current through the plates for a controlled period. It is common to use a significant amount of pressure for the procedure as well. In this method, heat is strictly restricted to the area that needs to be joined.
You can use resistance welding to join titanium and its alloys for a spot or continuous welds. It is particularly useful when it comes to welding titanium with other metals like carbon steel or stainless steel plates.
Laser-Beam Welding (LBW)
This is another fusion welding process that joins two pieces of metal together via a laser. It heats the intersection between the two plates, which melt and merge, forming the joint. Once the molten weld puddle cools down and solidifies, it results in a firm, durable weld.
Welders now increasingly prefer laser beam welding for titanium as it removes the need for a vacuum chamber. However, the use of shielding gas is still a must because the risk of contamination remains.
Even though a laser beam and electron beam are both fusion welding procedures, the scope of the former is more restricted. You cannot efficiently use the process on titanium plates more than 13mm in thickness.
Plasma Arc Welding (PAW)
Plasma Arc Welding is similar to TIG as it also uses an arc between a tungsten electrode and the workpiece. It is suitable for use on almost all titanium classifications and performs well even on thicker sheets of metal. Using the keyhole technique, you can also use it on a one-pass plate up to 13 mm thick.
Metal Inert Gas (MIG)/ Gas-Metal Arc Welding (GMAW)
MIG welding uses a solid filler metal wire that is continuously heated and fed via a welding gun. The process warrants the use of shielding gas to protect the weld puddle from contamination. Many welders prefer GMAW for its high metal deposition and productivity rates.
You can also use the process for titanium welds on plates that are more than three 3mm thick. Using the pulsed current technique, you can produce high-quality welds. The method proves less costly than others, especially for use on titanium plates more than 13mm thick.
Friction Welding (FRW)
As the name implies, the method uses friction to join two pieces of metal together. It is a solid-state weld process in which the resultant joint is as strong as the base. It’s widely used in various industries and is useful for joining pipes, tubes, or rods. It performs particularly well in situations where you can achieve joint cleanliness without the use of additional protective measures.
Tips and Tricks for TIG Welding
Here are a few tips and tricks for when you’re working with titanium.
- Use a standard GTAW welding power source combined with a high-frequency arc startup. Using a direct current electrode negative polarity with remote amperage control works well for welding titanium.
- Use a water-cooled TIG torch. They are able to perform high-temperature welds for more extended periods. Compared to air-cooled torches, they are also smaller and easily steerable.
- If you’re looking for a cheaper torch, we suggest that you opt for an air-cooled one instead.
- For welding titanium, you should use a 2% Ceriated Tungsten electrode:
- 1/16 inch or smaller for welding at less than 125 amps
- 1/16 to 3/32 inch for 125 to 200 amps
- For greater than 200 amps, you should use an electrode of around 3/32 to 1/8 inch in diameter
- Use a wide gas lens with a diameter of at least 0.75 to 1 inch. It allows you to perform longer welds by providing more extensive coverage.
- Use a porous copper purge block to provide even coverage to the workpiece from all sides. The copper acts like a lens and evenly distributes the shielding gas across the length of the workpiece from all sides.
- The ideal gas flow for purge blocks and trailing shields is 10 cubic feet per hour. For the torch, you should set it at 20 cubic feet per hour.
- For joints where the use of a purge block becomes impossible, you can DIY a chamber with stainless steel foil and fiberglass tape. Before you begin the weld, let the shield gas flow in the make-shift chamber long enough to allow the air to change at least ten times completely.
- To protect the material from contamination, always wear nitrile gloves when handling titanium.
- As important as choosing the right filler rod is, storing it appropriately is even more essential. After you select one and adequately clean the rod, you need to store it in an airtight jar to keep it safe for reuse in the future.
- Before welding, make sure you break down the oxide layer on titanium. To do that, use a grinder and a deburring tool. Make sure to reserve both tools for titanium specifically. Follow that up with the cleaning process.
- Wipe down the workpiece with a lint-free cloth using either acetone or a Methyl Ethyl Ketone solvent. You can also use a dilute sodium hydroxide and water solution to prep the surface for welding.
- You can also use a carbide file and a stainless steel brush to remove a light oxide layer from the titanium plate. Make sure to wear nitrile gloves and also dedicate the tools for use on titanium alone.
- You must maintain the post-procedure shielding gas flow until the temperature goes below 800 degrees Fahrenheit.
- We suggest that you use an infrared temperature gauge to ensure the titanium cools down to a safe range before you shut off the gas flow.
Welding titanium is essentially the same as welding any other metal. However, because of its high reactivity, it can become a tricky process. As long as you ensure that the material is properly cleaned before welding, you shouldn’t have a problem with the welding process. Ensure that you have the appropriate setup required to protect the metal against contamination. If you do this, the process becomes relatively straightforward.
Can you Weld on Titanium?
Titanium is as effortlessly weld-able as steel or nickel alloys, provided you keep its unique properties in mind. Using techniques similar to those of stainless steel and nickel-based alloys, you can fabricate titanium into almost any shape.
Before you start welding, ensure that you clean the surface with a proper chemical cleaner that does not contain chlorine and is not flammable. Adequately remove the oxide layer and rid the workpiece of all impurities before you begin welding.
As long as you can ensure that you provide an appropriate amount of coverage to the base material from all sides, you can guarantee a ductile and durable weld.
Can you MIG Weld Titanium?
Yes! You can MIG weld titanium even though most welders prefer TIG welding. With titanium, you run the risk of burning through the plate, which is why MIG welding is only suitable for welding on plates that are more than 3mm thick.
Can you Weld Stainless Steel to Titanium?
You can weld titanium and stainless steel together. As long as you use 99.999% pure Argon gas with either the TIG or MIG welding procedure, you can create a durable and robust weld.
Can Titanium be Welded to Aluminum?
Welding aluminum and titanium requires massive amounts of heat. You need to use an aluminum filler wire for the process. Joining of the two metals is possible if the temperature at the titanium side of the sheet remains below 2000 degrees Celsius. The material will melt at the intersection and produce a durable joint.
However, we suggest that you try to maintain titanium’s temperature closer to its melting point, which is 1670 degrees Celsius. Maintaining it at 1750 degrees Celsius will get you the ideal titanium weld with aluminum while simultaneously eliminating the risk of a burn through. As long as you keep titanium’s unique properties in mind and provide the right amount of coverage when you’re welding titanium, you should end up with durable, neat welds.