How to Weld Titanium?

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Titanium is a very strong and lightweight material that is used in many products, including aerospace engineering, military applications, medical supplies, and more. How do you weld titanium? How can you tell if it has been welded correctly? These are important questions to ask before welding with titanium. In this article, I will go over the various ways that titanium can be welded as well as what to look for when ensuring quality workmanship.

You Can Check Our New Article How to Weld Thin Metal?

Step-01: Clean the Surface

Before welding titanium, it is important that you make sure the weld joints are clean. You need to make sure the metal is free of things like dirt, dust, grease, oil, or moisture. If these substances are in the metal when you weld them together it can cause problems for your welding and will go bad faster.

Weld wire is clean when it comes from the store. If it looks dirty, you can clean it with a non-chlorinated solvent. But sometimes, you will need to use acid cleaning too.

On the other hand, the joint surfaces and the base plate need to be cleaned for at least an inch away from the joint. You can clean with household cleaners or detergents, and then rinse with really hot water and air dry.

You can clean the weld joints and other areas with solvents like acetone, MEK, and toluene.

The solvents are very good at getting rid of grease and oil. Use a new, stainless steel brush to scrub the surface. Never use a steel brush on titanium because it could damage the corrosion resistance that comes from not having iron particles in it.

Moreover, you can get dark stuff off by brushing it with a new steel brush. You can also do light grinding; draw filing, and acid pickling.

It is important to clean your metal with a pickle bath. This will remove all the dirt and oils from it. For titanium, you need to use 35% nitric acid and 5% hydrofluoric acid, which you put at room temperature. You dip the metal for 1-15 minutes depending on how dirty it is.

To clean things, you can use cold water. First, it will take the acid off. Second, you put hot water on it to dry it. Cleaning is finished when there is no more acid and it is dry. If there is a heavy scale and oxygen contamination, you should use mechanical means to remove the dirty stuff. You can use grinding or sandblast for that purpose too.

Molten caustic baths are useful, but you have to be sure that everything is done the right way. The first thing you do is take out the scales. Then, once they are gone, you can put acid on them to make them look better again.

Once joints are cleaned, they should be carefully protected. You should try not to touch them and only do the welding as soon as possible. When you are not working on them, keep them covered with paper or plastic so that they don't get dirty.

Step-02: Joint Fit-Up

Professional welders recommend that pipes or tubes smaller than 5 millimeters be welded with no filler metal. I usually recommend adding filler metal to pipes or tubes bigger than 5 millimeters because the pipe is too thick. But there are exceptions. For example, if the pipe is 9.5 millimeters or more, then you should put a v-groove in it and if the pipe is 2.4 millimeters or more, you should put a u-groove in it instead of just welding it without any filler metal.

Ultimately, to be safe, you should use your best judgment. Follow the rules. If you don't know what you are doing then find someone who does or asks for help.

The advantage of welding by hand is that it reduces heat and I do not need to worry about heat as much because we reduce time spent above 500-800 degrees Fahrenheit where oxygen and titanium can react and create a problem with welds.

In all the joints, it is important that they are tight. This will lower the amount of heat getting into your home and reduce how much of your house is exposed to oxygen.

Step-03: Select Proper Welding Processes

You may use any of the following welding techniques when welding titanium and titanium alloys:

  1. Electron-beam welding (EBW)
  2. Gas-tungsten arc welding (GTAW)  or (TIG) tungsten Inert Gas Welding
  3. Resistance welding (RW)
  4. Laser-beam welding (LBW)
  5. Plasma arc welding (PAW)
  6. Gas-metal arc welding (GMAW)  or (MIG) Metal Inert Gas
  7. Friction welding (FRW)

01. (EBW) Electron-beam welding:

It is one of the welding processes used to join titanium alloys. Electron-beam welding is very fast, about 2 times faster than the GTAW or GMAW. It has a high deposition rate and is used in medical applications due to its ease of process control and reduction of heat input to the weldment.

Advantages:

  • The electron beam penetrates into the weld metal resulting in a narrow heat-affected zone (HAZ), which increases heat input into the base material and enhances the depth of fusion, thus increasing fatigue strength.
  • Since 70% of the material can be reused in electron beam welding, it is economical.
  • The components can be welded with low heat input resulting in less distortion.

Disadvantages:

  • It requires expensive equipment which makes EBW uneconomical for general industrial use

02. (GTAW) Gas-tungsten arc welding (TIG) or (Tungsten Inert Gas Welding):

This process is done in manual mode either by hand or foot control operated through an inert gas shielding gas flow. The filler metal electrode is made of pure tungsten; therefore, no contamination by other elements occurs during the welding process. It provides better control over the arc and thermal cycling which results in good ductility and toughness of the weld metal.

Advantages:

  • It allows exact melting control which results in better weld bead contour, shape, and penetration properties.
  • It provides better control over the arc which makes it suitable for welding thin-walled components with low heat input.
  • The process is performed by highly skilled workers; therefore quality levels are high.
  • Welding consumables are not expensive as compared to other welding processes used for joining titanium alloys.

Disadvantages:

  • A large amount of filler wire is consumed during deposition (due to poor conductivity); as a result, wire feeders should be used for continuous operation. This increases the overall cost of equipment and production facilities significantly; therefore, it is not suitable for general industrial use.

03. (RW) Resistance welding:

The process provides excellent control over the penetration and helps to reduce burn-through and improve final weld properties. It also allows good surface finish without extensive cleaning, preheating or grinding; therefore, it is economical as compared to other processes discussed above. The components should be designed such that maximum resistance (i.e., the minimum thickness of base metal outside of weld region) can be achieved during welding operation to achieve desired strength through the resistance spot welding process. High tolerances are required in this process, however, general welding techniques can be used for joining titanium alloys. Chipping and grinding operations are required after completion of the resistance spot welding process which may increase the cost of production.

Advantages:

  • The process provides excellent control over the penetration and results in good quality welds with smooth contoured surfaces.
  • Welding consumables are economical as compared to other welding processes used for joining titanium alloys.
  • High tolerances can be achieved using this process; therefore, it is suitable for general industrial applications.

Disadvantages:

  • It requires special design consideration so that only minimum resistance is generated during welding operation which increases the cost of production per part significantly.

04. (LBW) Laser beam welding:

Laser beam welding uses a high-powered laser beam generated by CO2, excimer or diode lasers, capable of heating the surface of materials to very high temperatures. This heats the material surrounding the area being welded, which melts and fuses with other molten pools through capillary action. The laser beam penetrates into the base metal creating a small heat-affected zone (HAZ); therefore, this process is known as micro-welding because no significant amount of heat is deposited in base material outside the fusion zone resulting in negligible distortion.

Advantages:

  • It allows excellent control over the penetration profile due to low heat input.
  • The process provides good quality welds with smooth contoured surfaces due to limited heat input in base metal.

Disadvantages:

  • Welding consumables are expensive; therefore, it is not suitable for general industrial applications.
  • The welding process must be precisely controlled because the quality of welds depends on small variations in heat input and heating rates. The operator must possess very good experience to produce consistently, high-quality welds using this process.
  • It is not suitable for thick section components due to low heat input; therefore, it is suitable for joining titanium alloys with thickness up to 4mm only.
  • It requires special design consideration so that minimum penetration profile can be achieved which increases the cost of production per part significantly.

05. (GTAW) Gas tungsten arc welding:

This is one of the most commonly used welding processes because it allows better control over penetration profiles than gas metal arc welding (GMAW). It is preferred for joining thicker sections of titanium alloys.

Advantages:

  • It allows excellent control over penetration profile due to low heat input because it uses filler wire electrodes with high purity tungsten.
  • The process provides good quality welds with smooth contoured surfaces due to limited heat input in base metal.
  • Welding consumables are economical as compared to other processes used for joining titanium alloys.

Disadvantages:

  • The welding process must be precisely controlled because the quality of welds depends on small variations in heat input and heating rates. The operator must possess the very good experience to produce consistently high-quality welds using this process.
  • It is not suitable for thick section components due to low heat input; therefore, it is suitable for joining titanium alloys with thickness up to 4mm only.

06. (GMAW) Gas metal arc welding:

This process uses flux core or solid wire electrodes which may contaminate the weld pool resulting in inferior quality of welds; therefore, it must be used carefully. However, this process can be successfully used for joining titanium alloys because gas metal arc welding (GMAW) produces high penetration profiles between the edges of overlapping parts that are difficult to achieve using other processes like GTAW. Welding consumables for this process are economical as compared to others. It also has good control over penetration profile during welding operation because the process uses filler metal electrodes. The slag formed on the weld zone provides mechanical protection during cooling.

Advantages:

  • It is a relatively economical process as compared to other processes used for joining titanium alloys due to the low cost of consumables.
  • Welding consumables are inexpensive as compared to other processes used for joining titanium alloys.
  • The slag produced on the weld zone acts as a sound shield that prevents base material from contamination by producing a gas shield, thus resulting in high-quality finishes with smooth contoured surfaces.

Disadvantage:

  • This process requires skilled operators and very good experience for better control over penetration profile during welding; therefore, it is not suitable for general industrial applications.

07. (SAW) Submerged Arc welding:

This process uses submerged arc welding equipment to generate heat directly in the material without any need for gas shielding. This process is very suitable for joining titanium alloys because it can produce high-quality welds with smooth contoured surfaces due to limited heat input in base metal.

Advantages:

  • Sawing process is suitable for joining thick sections of titanium alloys because it can produce high penetration profiles in thicker components due to low heat input in the base material.
  • Welding consumables are economical as compared to other processes used in joining titanium alloys; therefore, it is preferred for industrial applications where higher deposition rates and production rates are required.

Disadvantage:

  • The slag on the weld zone prevents the gas shield from covering the molten metal which might lead to contamination of the weld zone resulting in poor quality finishes and lower strength properties of joints. Hence, this process is not suitable for critical industrial applications.

Step-04: Determine Which Type of Welder to Use for Titanium

The process of welding titanium is straightforward. Welding in a Direct Current Electrode Negative (DCEN) setting is recommended. This means that a transformer or inverter-based power source will work. You don't need an AC power source unless you weld other types of metal. Considerations:

  • It needs to be DC, and not AC because it's for welding titanium metal
  • You can use a transformer or inverter-based power source
  • You don't need AC unless you weld other types of metal.
  • High-frequency arc starting capabilities are important. The tungsten should never touch the base material.
  • Pulsing capabilities are good for reducing heat, making the arc stable, and increasing penetration. Pulses can do this. Some inverters have more pulses than others which might be better depending on what you need your inverter to do.
  • When you are welding, make sure that the power source is low amperage. This will work for most titanium tube/pipe welding applications.
  • In this application, either an air- or water-cooled torch will work. The type of torch you use depends on the situation. Water-cooled torches are small and a bit more expensive but they give people comfort and easier access to joints. Air-cooled torches are a bit bigger, but they cost less and can probably be used for most titanium welding joints.
  • Step-05: Select Proper Power Supply

    When you are welding titanium, you can use a power supply that connects to the metal with D.C. straight polarity or D.C. reverse polarity, depending on the type of welding machine you are using.

    You should also have a remote-controlled contactor so that when the arc is broken it does not have to be removed from the cooling weld metal, so gas can still shield it while being welded together for an even better effect.

    Other desirable features would be to have foot-operated current and contactor control, high-frequency arc starting, and a way to start the shielding gas automatically.

    Step-06: Select the Proper filler Rod

    You're looking for a titanium filler rod. This is a type of metal that has been proven to be useful in the construction of items such as airplanes, boats, and buildings.

    It's an entirely recyclable material that can't corrode from water or other natural elements. Plus, it's being considered for international use because it can withstand intense heat levels without melting like some metals do (including steel).

    I prefer to use tungsten that is both thorium and lanthanum. AWS D10.6 recommends it. However, I have seen people use two-percent ceriated tungsten electrodes.

    Tungsten is a metal that needs to be ground to a point. It should be the size of 1/16-inch or small for less than 90 amps, 3/32-inch for 90-200 amps, and 1/8-inch tungsten for more than 200 amps.

    Filler metal is exactly the same thing as the metal it is to fill. But sometimes people use different filler metals so they can do things like making their metal bandier. The filler metal should match the process you are using for welding, not what you are doing with your hands.

    Step-07: Maintain Sufficient Gas Coverage

    Titanium reacts with oxygen the most when it is hotter than a certain temperature. The common wisdom for what this temperature is can vary, but I know that it will be close to 500-800 degrees Fahrenheit.

    That reaction makes metal weak and does not protect against corrosion. You need to make sure you put something in the way of the fire (like gas) and keep it there until it cools down. This is important because if you don't, the metal will get weak and then break when it does not have enough support.

    Most of the time, titanium pipe welding is done outside. But there are times when you need to be protected from gas. A purged chamber offers protection but it is expensive and hard to move around in.

    In order to weld a titanium tube or pipe, you need to have argon. You can use it as both a shield and backing gas. You need to use argon that has no more than 20 parts per million (ppm) of oxygen and/or a dew point greater than -50 to -76 degrees Fahrenheit. Sometimes, you need to use argon with the highest purity, 99.999%.

    You may have to use a mix of 75% argon and 25% helium or 70% argon and 30% helium as shielding gas. But this is not common. Helium may be used as backing gas, which has the same general effect as argon.

    On the other hand, the primary gas for the arc is argon because it provides more stability, is cheaper, and is more available than other gases.

    Two components that you might not use in other TIG welding applications are important for shielding. You need a gas lens and a trailing shield.

    The gas lens is like the collet body, but it makes the flow of shielding gas better and covers the tungsten, the arc, and the weld pool more.

    Trailing shields are for when you are welding. It is when the metal is hot. It makes sure that the metal doesn't get too hot or cool down too much. You can buy them, but they are better if you make one because it will be exactly what you need.

    You need to use a clean, non-porous hose for all your shielding gas. Rubber will absorb oxygen and that could make your weld bad. Some people also use cups that are very big and they cover the weld more than is necessary.

    To have a good level of coverage while you are welding, follow these steps:

  • Primary Shielding – To make a good weld, you need protection from the heat. A welding torch is usually what does this. It is built in the welding torch and provides primary coverage for protecting the molten weld puddle from excess heat. The best type of torch to use has a ceramic cup that cools with water and gas lenses. You should get one that has a broad cup for better coverage.
  • Secondary Shielding – Trailing shields are a special tool that is attached to the end of a welding torch. They keep the areas from being contaminated because they make sure that these areas stay safe, even if they get hot. They provide secondary protection.
  • Backup Shielding – These devices that look like trailing shields at the end of your welding torch are called trailing shields. Sometimes they come with a pre-fit device, but usually, they don't and you have to tape them to your torch yourself.
  • Step-08: Use Proper Welding Technique for Welding Titanium

    In addition to a clean joint, welding wire, and right gas, you need to have a good technique. You can't do it while using the wrong kind of wire or while using the wrong kind of gas. It's also important to make sure that all air is gone before you start because if there's any in the way, then the weld will be bad.

    Whenever you can, use a high-frequency arc starting. This way tungsten inclusion can't happen.

    When the welding is done, you should use a current upslope and a contactor. You can stop shielding when the metal has cooled below 800°F (427°C). In addition to the primary shielding, another layer of protection is needed. The secondary and backup shields should be used. This is a layer on top of the primary shielding. The blue color on a weld means the gas wasn't removed before welding.

    Preheating is not needed for titanium shop welds, but if you think there might be moisture then you might need to preheat. You can use a gas torch to heat the welded area to about 150 degrees Fahrenheit.

    Do this on an open flame. For welding titanium without using filler metal to make the welding, the arc length should be about the same size as the diameter of your stick electrode. If you want, you can add metal that will fill the space. The arc length should be 1-1/2 times the diameter of your electrode.

    Filler wire should be put in the place of the weld joint. It should go into the area where the flame is at.

    When you use a dipping technique, the wire may get messy. This is because of turbulence. Whenever the welding wire is removed from the gas, it should be cut off at least 1/2 inch. This will remove all of the metal that was contaminated. In order to keep temperatures at a cooler temperature, you do not need to add more shielding.

    When you are welding, if the bead stays shiny and silvery-looking, it is not important to clean the area before you weld again. If your weld starts to look like straw or light color, use a brush that is made out of stainless steel.

    If your weld beads have a dark blue or white color, they are contaminated and you must grind them off. You need to carefully prepare the joint and clean it before you weld.

    Step-09: Evaluating Weld Quality

    In order to have a welding job on titanium, you need to do a lot of tests. You need to know what is going in the weld before you make it. For example, if the weld is going in a pressure vessel for construction work, then there are special codes that tell you how to do it and what happens when you put the weld in.

    Tensile and bend tests are what you do to make sure your welds are good. If you had a test that was an impact or notch tensile one, then you would also need it for low-temperature applications.

    Once you know the best way to do something, it's important to keep doing it. If you find a good way of doing something, like testing whether or not a thing will break, then you should always use that same process again and again.

    • Bend Test:

    Bend tests are a good way to see how ductile your welds are. A bend test can show you if the weld is strong or not. You make this test on trial welds and on extensions of production welds. So this test is used to make sure that your welds are good.

    If you use a bend sample with the weld perpendicular to the axis of bending, it will make sure that the metal in the sample is uniformly strained. This also helps you get more accurate results.

    Good quality welds should be able to bend without cracking. Problems with titanium welds are usually because of contamination. The color of the weld can tell you how much shielding was used and so you know if it is good or bad.

    Hardness measurements on welds are also sometimes used to tell how good the welding is. If the hardness of your weld is no more than 30 points greater than the hardness of metal you were working on (on the Knoop, Vickers or Brinell scales), then you did a good job. However, it might not be that simple. There could be some different chemicals in there that change what happens to metal when it's heated up and cooled down. This could result in higher hardness without any contamination. If this does happen, but there is no other sign of contamination, then just go back and fix your work.

    The ASME Code tells you to remove titanium welds that are more than 40 BHN harder than the metal they are welding. It is necessary to do this when there is a lot of contamination in the weld. They also tell you to look for liquid penetrant and radiography when welding with titanium.

    Conclusion

     If you’re looking for a new hobby, welding titanium is the way to go. Not only will it give you an opportunity to create your own metal projects, but it also provides immense satisfaction when completing tasks that are hard on other materials like aluminum or steel. Now that you know how to weld titanium, what are you waiting for? Start working with this metal today! With all the benefits of welding titanium and its easy process, it’s hard to find a reason not to try.

    Last Updated on October 25, 2021 by weldinghubs

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