TIG or tungsten inert gas welding is a technique used to heat or joint two metals together with the help of a tungsten electrode. Using this method, you can weld a variety of metals like stainless steel, nickel, chrome, copper, aluminum, bronze, and even gold. The topic here under discussion is the TIG welding of stainless steel. So, we would only focus here on stainless steel welding. let’s have look at some of the points that needed to keep in mind before we conclude TIG welding stainless steel AC or DC, which is the optimum choice.
It is an alloy that has chromium in it. Chromium is the reason for its essential property of shining. Another property of stainless steel which distinguishes it from the other metals is that it doesn’t corrode or rust in the atmosphere. It is widely used in industrial sectors like the automotive industry, aerospace, chemical industries, food processing industries, etc. The welding of stainless steel is a highly critical phenomenon. You need to keep in mind many factors while doing welding of stainless steel. Let’s have a look at these critical factors.
Use all the personal protective equipment. The area must be ventilated enough that you keep yourself safe from the fumes of welding. Keep yourself safe from live electric wires. You can also thoroughly study the American national standard Z49.1 and occupation safety and health administration standard for this purpose.
Joint design and fit-up
For solid metal bonding, joint design and fit are the critical factors to consider. You must be completely aware of the metal thickness, joint accessibility, welding position, etc. Usually, we adopt butt, corner, tee, and lap type joints for this purpose. For keeping the workpiece in place, many fixtures and jigs are also adopted at the end.
We can take a variety of welding methods available, but here we only talk about TIG welding. TIG welding is an electric arc welding procedure in which electricity is used to generate heat between the base metal and a non-consumable tungsten electrode. Moreover, you can also filler metal and inert shielding gas for the protective atmosphere surrounding the welding.
Appropriate inert shielding gas
As far as the TIG welding is concerned, you can take argon gas for metal having thickness up to ½-inches. If the metal is thicker, you can also take a mixture of helium and argon or pure helium. Pure helium is an excellent choice for deeper penetration.
If both the pieces belong to the same alloy, you must choose the filler metal, which is the same as the base metal, to ensure the same weld properties. If these are dissimilar, then the filler metal selection would depend on many factors like compatibility, mechanical properties, and durability.
TIG Welding Stainless Steel AC or DC? Let’s End This Debate
When you are going to weld stainless steel with the help of the TIG welding technique, you must have some factors like the welding position and thickness of the plate you will weld. Usually, it takes DC with a straight polarity which is electrode negative. In this technique, the current flows in one direction continuously through the welding circuit. You can easily ignite the arc and maintain it for some time. The technique is perfect for the small diameters and lowers current settings. You must use a pointed tip while doing welding. If you want to make a butt or corner weld, you must use the tungsten with 5-6 mm stick thickness.
On the other hand, the AC uses both straight and reverse polarity. In this case, there is less chance of arc blow, and it is perfect for welding thick metals having large diameters. Always use a ballad tip for AC welding.
Now it’s you clear about the Difference between AC or Dc to use in accordance with your scope of work. Now it’s time for you to get your TIG welder and get the job done in style, nothing can stop you now.
Base metal cleaning
Take care of cleaning before the welding to prevent the formation of oxides. There must no dirt, grease, oil, and paint on the surface. It would also help make stronger and smoother joints. To remove burrs and oxide from the surface, you can use a stainless steel wire brush. Wear gloves for cleaning purposes.
Preheating is not compulsory in TIG welding, but it is necessary for welding some specific materials. The austenitic grade steel grade stainless steel doesn’t need to preheat before applying to weld, but it is necessary for the ferritic and martensitic like stainless material. Moreover, it is also extremely necessary to weld thick metals or metals with a percentage of carbon.
If you want to reduce the internal stress on the metal, then post-heating will help you. It would slow down the cooling process and minimize the cracking process. Post heating is highly beneficial when you weld thick metals together.