MIG Welding Stainless Steel

Basics of MIG Welding Stainless Steel and Nickel Based Alloy

MIG Welding Stainless Steel and Nickel Based Alloys is pretty straight forward. The weld has many of the same characteristics as a carbon steel weld. In reality you should not be welding stainless steel or nickel based alloys until you master carbon steel. Besides a easy learning curve the MIG Welding Process works on stainless steel just fine with the exception of two issues:

  • Joint Set-Up/Weld Joint Distortion
  • MIG Gun Cord/Liners Issues

What Nickel Based Alloys Need for Weld Joint Set-Up and How to Control Weld Distortion

GMAW_2F_StainlessSteel_Pipe_to_Plate_WeldJoint set-up for stainless steel requires a pretty cleans surface but the real big issue controlling metal distortion. Obviously a clean joint is ideal for all welding situations so the same rules apply to stainless steel as carbon steel. The distortion of the weld is controlled in two ways:

  • Bracing the Weld Joint
  • Spreading Out the Heat

Bracing the Weld Joint

Bracing the Weld joint is done in many ways. It can be as simple as wedging a piece of wood between two sides to keep them from closing in (hopefully you will be able to remove it later). All the way to creating a scaffold like system of supports put in place to control the distortion. Each weld joint is different in terms of “How do I brace it to control the distortion”. Another way of bracing the weld area is building a jig to keep all of your parts in place while welding. It really comes down to each situation is different and how much weld is needed. The more welds that are needed the more bracing you will need. With stainless steel and nickel based alloys every joint needs bracing and that also includes spot and tack welds. Stainless distorts just that much.

The Big lesson for MIG Welding Stainless Steel is brace your joints well, make as many tack welds as needed and spread your heat evenly throughout the joint.

Spreading Out the Heat

Spreading out the heat is the main technique for welding g Nickel Alloys and Stainless steels. The weld is spread out by staggering, back stepping and/or waiting for the joint to cool before welding any further. Stainless heats up very quickly and holds that heat for a very long time compared to carbon steel. The distortion heat causes can literally be seen as you weld. Thin Stainless Steel will move inches as you tack weld and a simple 90 degree tee joint can distort as much as 45 degrees.

The Big lesson for MIG Welding Stainless Steel is brace your joints well, make as many tack welds as needed and spread your heat evenly throughout the joint.

MIG Gun Cord and Liners Issues for Stainless Steel Welding

Stainless steel MIG welding does not require any special equipment! In the case of welding stainless steel, the biggest problem comes from the cord or liner of the welder. The trick when welding stainless steel is to keep the cord as straight as possible. Otherwise, the wire feed that feeds the weld joint will have too much friction due to stainless steel electrode being stiffer then carbon steel. Think of trying to shove a wire hanger through a bent garden hose. Chances are if the hose is straight you can easily put it through. If the hose is bent, you will have difficulty. That is how stainless steel wire is in the liner of the welding cable. What happens is the wire is so stiff in the liner that it causes so much friction that the wire stops the feeding wheel from feeding the joint (literally spinning its wheels). The result is a fused MIG tip. That is when the wire stops or slows down to the point that the arc melts the wire up to the MIG tip and it welds itself to it. The other major problem is again the liner. If you bend the cord to much the friction stops the wire and the wheels that are feeding the MIG gun push the wire so hard that the wire having no place to go spooling up like a birds nest before it gets pushed into the liner.

Alternative Equipment for Stainless Steel MIG Welding

There is a solution to these minor issues with the liners and they are using either a “spool feed guns” or a “Push Pull Wire Feed System”. They are not necessary but do make life a bit easier for the right price.

Millermatic_350P_Double_Roller_Aluminum_Push_FeedPython_Gun_Pull_Feed_Bottom_ViewMIG_Welding_Spool_Gun

Dangers of MIG Welding Nickel Based Alloys from Hexavalent Chromium

Let’s address the elephant in the room nobody want to notice, mention or talk about! Hexavalent Chromium fumes are extremely dangerous and are produced by welding nickel based alloys, stainless steel and chrome alloys (another nickel based alloy). This stuff does not kill you today or tomorrow. These types of fumes take years (about 10 to 20) to cause lung cancer and exposure levels are what determine your risks. Learning to weld stainless is pretty harmless (so they say) but if you do it for a living you should always use the proper ventilation and a “Hepa” filter respirator or air supply system. The bottom line is you need to be safe and if you weld these alloys for a living do it safely and DEMAND TOP DOLLAR.

Overview of MIG Welding Stainless Steel and Nickel Based Alloy

The process, equipment, and techniques for MIG welding stainless steel are almost the same as for carbon steel. The main difference is weld distortion control and the cost of the materials. This Alloy requires a lots of bracing and it cost it many times that of carbon steel. If you are just learning don’t waste your money on these alloys until you master carbon steel welding. It’s a little easier, a lot cheaper, and way safer for you!

Next: How to Choose Stainless Steel MIG Welding Electrodes and Gasses