TIG welding (GTAW) is an effective and precise way to weld stainless steel. In fact, if you’re looking for high-quality stainless steel welds, TIG welding is the best choice. It’s a challenging process to learn, but with some practice, you’ll get the hang of it and, before long, will be laying down high-quality weld beads.
This article will outline what you need to get your stainless steel TIG welding project off the ground. You’ll learn the challenges, and types of stainless steel, how to set up everything from gas to your TIG machine, and finally, how to put everything into practice to produce high-quality TIG welds on this beautiful metal.
TIG welding is one of the most challenging welding processes to master. But that isn’t to say you shouldn’t use TIG welding for your next stainless steel project. You just need to understand what challenges await you. Once you mastered TIG welding stainless steel, you can create beautiful-looking welds.
TIG welding requires more of your attention compared to other welding processes. All you need to do in MIG welding (GMAW) is control the gun angle and travel speed. However, in TIG welding, you must control the amperage, the filler metal, travel speed, torch angle, and arc length.
Getting the muscle memory you’ll need to make TIG welding easier takes practice. I spent many hours practicing before I could weld without thinking about all the variables I needed to control. It’ll be discouraging initially, but if you stick with it, you’ll succeed.
You’re in direct control of how much heat you put into the base metals. Since TIG welding is slower than MIG, you are putting more heat into the base metal. The extra heat will cause more distortion and other heat-related issues.
The cost of the welding equipment, consumables, and materials is another challenge of TIG welding. The welding machine alone will be more expensive than a MIG or stick welding machine. Then there are tungsten, gas, filler rods, gas lenses, cups, and collets. These items wear out. In most cases, you’ll need several sets to suit different tungsten diameters.
Read How to Weld Stainless Steel Easily: 3 Common Methods Compared.
Stainless steel has many types and grades, determined by its alloying elements. There are three main types you’ll most likely come across:
Austenitic – Austenitic stainless steel is most appropriate for most GTAW projects and also the most common type you’ll encounter. It’s known to contain chromium, nickel, manganese, or molybdenum. Austenitic also has excellent corrosion resistance and weldability. Popular grades include 304, 310, and 316. Either has good weldability, but 304 is usually the more affordable option.
Ferritic – Ferritic stainless steels have a lower nickel content, making them more affordable. Yet, the presence of more chromium and molybdenum improves their toughness. Unlike austenitic stainless, ferritic stainless steels are magnetic. Some common grades are 409, 430, and 444.
Martensitic – This type of stainless steel is the least common. It has a high carbon content and can be hardened by heat treatment. It’s also magnetic and has poor weldability. Some common grades are 410, 420, and 440.
Before you start welding, you need to make sure that your TIG welder is properly set up for stainless steel. Here are some of the main factors you need to consider:
The most common shielding gas for TIG welding stainless steel is pure argon. It provides good arc stability and weld quality. You can also use a mixture of argon and helium, which can increase the heat input and penetration. However, this can also increase the risk of distortion and porosity. The recommended gas flow rate is between 10 and 20 CFH.
The most common tungsten electrode for TIG welding stainless steel is 2% thoriated (red). It has good arc starting and stability, and a low rate of consumption. You can also use 2% ceriated (grey) or lanthanated (blue) tungsten, which have similar characteristics. The recommended tungsten diameter is between 1/16 and 3/32 inches, depending on the amperage and thickness of the material. You should grind the tungsten to a sharp point, with a taper of about 2.5 times the diameter.
The most common filler metal for TIG welding stainless steel is ER308L. It matches the composition of 304 stainless steel and has good corrosion resistance. You can also use ER316L, which matches the composition of 316 stainless steel and has better resistance to pitting and crevice corrosion. The recommended filler rod diameter is between 1/16 and 1/8 inches, depending on the thickness of the material and the joint design.
The most common polarity for TIG welding stainless steel is DCEN (direct current electrode negative). It provides the most heat to the base metal and the least heat to the tungsten, resulting in a narrow and deep weld. You can also use AC (alternating current), which provides a balance of heat to the base metal and the tungsten, resulting in a wider and shallower weld. However, AC can also cause more spatter and noise.
Now that you have everything set up, you’re ready to start welding. Here are the basic steps you need to follow:
Clean the base metal and the filler rod with a wire brush or a solvent. Any dirt, oil, or oxide can contaminate the weld and affect the quality and appearance of the weld.
Clamp the workpiece to a metal table or a fixture. This will provide a good ground connection and prevent the workpiece from moving or warping.
Adjust the amperage on your TIG welder according to the thickness of the material and the joint design. A general rule of thumb is to use 1 amp per 0.001 inch of thickness. For example, if you’re welding a 1/8-inch thick material, you should use about 125 amps.
Hold the torch in your dominant hand and the filler rod in your other hand. Position the torch at a 70 to 80-degree angle to the workpiece, and the filler rod at a 15 to 20-degree angle to the workpiece. Keep the tungsten about 1/8 inch away from the workpiece, and the filler rod about 1/16 inch away from the weld pool.
Press the foot pedal or the finger control to initiate the arc. Move the torch along the joint at a steady speed, while dabbing the filler rod into the weld pool at regular intervals. Keep the arc length and the filler rod distance consistent throughout the weld. Avoid touching the tungsten or the filler rod to the base metal, as this can cause contamination and defects.
When you reach the end of the weld, gradually reduce the amperage and the filler rod feed. Break the arc by releasing the foot pedal or the finger control. Do not move the torch away from the weld until the weld pool solidifies, as this can cause oxidation and porosity. You can also use a post-flow gas to shield the weld until it cools down.
TIG welding stainless steel is not as hard as it seems. With some practice and patience, you can achieve high-quality welds that look and perform great. Just remember to follow the tips and steps in this article, and you’ll be on your way to becoming a TIG welding master.