MIG welding titanium process: how to do it and factors to consider

Many welders who have not tried to weld titanium or who have not had any experience in titanium welding feel that welding titanium is difficult.

However, welders who regularly weld titanium in their fabrication facility claim that the process is remarkably comparable to that of welding stainless steel and nickel alloys. Of course, you need to exercise caution and adhere to standard practices.

Is titanium hard to weld?

This article will address welding titanium-related topics such as titanium welding, procedures for titanium welding, filler wire for titanium welding, and titanium welding-related queries like whether titanium can be MIG or be stick welded, whether it can be welded with mild steel, and whether it can be welded with aluminum.

Due to its extreme reactivity, titanium has traditionally only been welded in completely enclosed spaces.

However, welding titanium is not as challenging as people may believe. You can weld titanium with ease if you use the right gas shielding and safety precautions. We will explain MIG titanium welding in this article.

A few characteristics of titanium are essential to the welding process, doesn’t matter if it is TIG, MIG, or plasma arc welding:

• Compared to most metals, it has a lesser density.
• It is less flexible than other metals.
• Compared to stainless steel, it is less ductile.

What type of welder is used for titanium?

Titanium and its alloys are most often welded with the gas tungsten-arc (GTA or TIG) and gas metal-arc (GMA or MIG) welding processes.

GTAW/TIG welding titanium

The welder’s primary preference for welding titanium is TIG. A non-consumable tungsten electrode, a portable filler wire, and a shielding gas are all used in TIG welding.

TIG welding titanium requires pure argon shielding on the molten weld pool as well as on the hot weld metal behind it, which is a key distinction from TIG welding metals like stainless steel (the weld bead behind the weld pool will be still hot enough to react with oxygen and other components of atmospheric air).

In comparison to other welding techniques, TIG welding allows the welder superior control over the heat input and the molten weld pool. TIG welding also has remote current control capability, a post-flow timer, and high-frequency (non-touch) arc initiation.

According to AWS D10.5, tungsten electrodes that have been thoriated (contain thorium oxide) or lanthanated (contain 1.3 to 1.7% lanthanum) are best for TIG welding titanium.

Even the smallest contaminant in the shielding gas argon can turn the weld color straw-yellow, so it must be 99.999% pure. There is a problem with the argon’s purity or flow if you notice a blue tint when you weld titanium. Argon should begin to flow far before you even contact the high-frequency start arc.

Shielding gas can be used for primary, secondary, and backup shielding in TIG titanium welding. For the argon cylinder, a dual flowmeter is an option.

Primary shielding

The molten weld pool is shielded and protected primarily through the titanium welding torch. To allow additional argon for shielding, use a ceramic cup with a bigger diameter (3/4″) for the welding torch.

Secondary shielding

Using a specially constructed TIG torch, you can use an argon gas trailing shield.

Backup shielding

The backup shielding aims to cover the heat-affected zone and the root side of the welding with argon (HAZ). Titanium pipe welding will benefit from this. For titanium welds workpieces, an argon shielding purge fixture can be created.

As an alternative, you can use an inflatable chamber or a metal chamber that is walled off and filled with argon to create a clean environment for welding titanium. For welding, such chambers will feature a place where your hands can be inserted wearing gloves.

The weld pool needs protection from an argon shield until it cools to temperatures below 500 °F after titanium welding is finished since it is still hot.

For welding titanium, you can utilize a DC (direct current) power source that is based on an inverter or transformer and the DCEN (direct current electrode negative) option. Because the tungsten electrode shouldn’t touch the titanium workpiece, the TIG system needs to feature a high-frequency (non-touch) welding arc initiating system.

The ability to pulse TIG weld titanium will help you manage the heat input and increase arc stability and penetration.

You can test the welding on a scrap piece of titanium metal before beginning the actual welding to make sure everything is in order.

Up to a thickness of 3 mm, TIG welding can be done in a single pass; above that, multiple passes may be necessary. Because of this, TIG is ineffective for welding titanium on objects that are thicker than 3 mm.

The following elements are necessary for TIG welding titanium:

• shielding gas made of argon, which is extremely pure (99.999%).
• tidy workplace
• titanium workpieces should be clean and dry
• adequate argon shielding along the whole length of the weld
• high-frequency non-touch arc starting
• utilizing the filler wire and tungsten electrode that is advised
• following the weld preparation process exactly
• holding the torch stationary while the argon is turned on until the metal has cooled to less than 500 °F

These guidelines guarantee consistent silver and glossy weld metal.

Can titanium be welded with MIG?

Although titanium may be welded using MIG, most welders choose TIG instead. More than 3 mm thick titanium can be welded using MIG welding. If you MIG weld titanium that is less than 3 mm thick, there may be a chance that the metal will catch fire.

For welding titanium metals 1/2″ and higher, MIG welding is cost-effective. Direct current electrode positive (DCEP) electricity is used for MIG welding.

A MIG welding torch can be used with a ceramic cup that is 1 inch in diameter. Similar to TIG welding, make sure there is enough shielding gas along the whole length of the weld.

MIG welding can fulfill the need for a titanium welding procedure that is more productive. In MIG welding, an arc is created between a titanium wire electrode that is continually fed and a titanium workpiece.

The molten weld pool weld metal and the hot weld metal behind it are shielded by an inert gas. When compared to TIG welding, MIG welding titanium has a much higher weld deposition rate.

When welding titanium using a MIG process, helium is typically utilized as the shielding gas; argon can cause the welding arc to become unstable.

MIG is thought to have the ability to weld titanium well, although arc stability needs to be addressed.

The titanium oxide layer on the workpiece releases electrons more readily when you MIG weld titanium than it does when welding base metal titanium, which causes a phenomenon known as wandering (according to welding researchers). This issue (how to check this wandering) is being addressed to develop a practical MIG welding for titanium.

It was discovered that by applying a high-frequency micro-oscillation to the contact tip of the titanium wire, the wandering problem could be managed and the quality of MIG welding titanium could be enhanced.

How to assess the quality of titanium welding

The quality of the titanium weld can be determined by the color of the weld. A silver and brilliant weld bead is typically a sign of a high-quality weld. For some applications, weld beads in the colors of light straw (light yellow), dark straw (dark yellow), and brown may be appropriate.

Dedicated stainless steel brush

These weld beads can be utilized after being carefully cleaned with a dedicated stainless steel brush. The creation of the oxide is what gives the color.

The same may not be accepted if the weld bead is violet, dark, light blue, green, gray, or white. In such a case, the entire weld bead is removed by grinding and re-welded.

If the weld bead is bright silver, cleaning it in between the numerous weld runs is not necessary. The weld bead, on the other hand, must be completely removed by grinding and re-welded if it is polluted (dark blue or gray hue).

How to MIG weld titanium?

A good titanium weld will be bright and reflective, similar to frozen mercury. You should first follow a few measures to prepare the weld surface for welding titanium to ensure that you generate a weld of high quality.

Clear the place

You should always prepare your surface before you MIG weld titanium. With titanium, you must, however, use extra caution. Your surface will be more durable if it is cleaned. A brittle joint can be caused by cutting fluid, paint, oil, dirt, filth, rust, and other substances, and thus constitutes a weld failure.

Follow the three C’s for a good and long-lasting weld:

• clean surface
• tidy work area
• pure filler rod

You run the risk of contaminating your workpiece if even one of these surfaces is dirty. We advise using a chemical cleaner made especially for titanium to get rid of all foreign objects from the surface.

Utilize a stainless steel brush or a steam cleaner and a diluted sodium hydroxide solution to clear the work surface of all impurities. After that, blow out all the wetness from the workspace using a hot air blower.

On any flammable chemical solution, avoid using a hot air blower. To clean the workpiece, you must ensure that the chemical cleaner you employ is not flammable.

Before usage, all the equipment should be cleaned and dried. The same solution that you used for the workstation can be applied to the tools.

Make sure the cleanser is not chlorine-based because chlorine does not react well with titanium. Use cotton or plastic gloves instead of rubber ones, as they don’t contain any chlorine.

Select a shielding gas

The correct inert gas shielding gas must be used to achieve a strong weld since titanium rapidly forms brittle compounds when it comes into contact with air, grease, dirt, moisture, and other metals. Welders often do the procedure using 99.999% pure Argon. The best protection against the environment is only offered by extremely pure argon and helium.

Make sure you only purchase shield gas from reputable vendors when you acquire it for your welding operation. Discoloration may occur even if the Argon is somewhat less pure than necessary. You don’t want to have a weld that has a yellowish tint because it will be the result. Blue coloring and mottling can also be caused by impure gas or insufficient covering.

With titanium, you must ensure that the back is kept shielded from the atmosphere as well as the front. Any part that has been exposed to heat will respond negatively to oxygen contact.

Use shielding gas-filled enclosed compartments built of glove boxes for smaller components. You can even employ purge monitors and specially designed polyethylene purge gas chambers. You can use them to confirm that there is sufficient argon in the chamber to offer the best possible protection.

The following three procedures must be taken if you want to have the appropriate level of coverage during welding:

• Primary shielding is typically integrated into the welding torch and offers the initial coverage required to safeguard the molten weld puddle. A typical water-cooled torch with a ceramic cup and gas lenses is available for usage. For optimum coverage, we advise using a torch with a larger cup.
• Secondary shielding: Trailing shields offer further defense. They ensure that all heat-affected areas are kept free from contamination, and are often attached to the end of welding torches.
• Backup shields perform essentially the same function as trailing shields and have a similar appearance. They are either portable gadgets or have tape holding them in place. They almost seldom arrive already fitted to the welding torch.

Choosing the proper filler wire

We advise selecting a filler wire that largely possesses the same qualities as the base material for welding titanium and its alloys.

Another option is to choose a wire that is rated at a strength level one grade lower than the base metal. In some circumstances, the welder might even switch out the filler wire entirely.

The characteristics and configuration of the joint will influence the filler wire you choose. To improve joint ductility:

• Use a filler metal with a lower yield strength of the base when welding unalloyed titanium that has higher strength.
• When welding titanium that falls under the Ti-5A1-2.5Sn and Ti-6A1-4V classes, unalloyed filler metal can be used.
• Another choice is to use filler metal that has less base metal in the way of oxygen, nitrogen, hydrogen, carbon, and other alloying elements.

Possible welding techniques

The following welding techniques can be used to join titanium and titanium alloys:

• (GTAW) Gas-tungsten arc welding or (TIG) tungsten Inert Gas Welding
• (RW) Resistance welding
• (LBW) Laser-beam welding
• (PAW) Plasma arc welding
• (EBW) Electron-beam welding
• (FRW) Friction welding
• (GMAW) Gas-metal arc welding or (MIG) Metal Inert Gas

Gas-metal arc welding (GMAW) and metal inert gas (MIG) 

Solid filler metal wire is heated constantly and fed through a welding gun in MIG welding. To prevent contamination of the weld puddle, the procedure justifies the use of shielding gas. Due to its high metal deposition and productivity rates, GMAW is favored by many welders.

The method can also be used to fuse titanium onto plates that are thicker than three millimeters. You may create welds of excellent quality using the pulsed current method. The technique proves to be less expensive than others, especially when used on titanium plates that are thicker than 13 mm.

Conclusion

Due to its many benefits, titanium has become a more popular metal throughout time. It is used in crucial businesses like those that produce goods for the military, atomic reactors, aerospace, and ships.

A welder who can create titanium can be paid highly and respected. We sincerely hope that this post has shed some light on the subject.

FAQ

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