Stainless steel should go right up there with airplanes and liposuction as far as world-changing inventions are concerned. It’s an incredible useful material that resists corrosion and all-around makes our world a much easier place to live. But let’s make no mistake, the word “stainless” isn’t the only thing that separates stainless steel from mild steel. Although welding stainless steel might differ from your normal technique, the solution is to simply know the right steps and you’ll soon be able to weld stainless steel just as easy (or easier) than mild steel.
The trick to identifying stainless steel is first to look at its color, then to figure out if it’s magnetic. Stainless steel is characterized for its shine. However, sometimes highly polished pieces of mild steel can mimic the shine of stainless. It’s always a good idea to place a magnet on your workpiece. If the magnet won’t stick, it’s probably stainless.
For each of the main welding processes, stainless steel welding is handled differently. We’ll take you through some pro-tips for Stick, MIG and TIG welding.
When it comes to welding anything new, the first thing to figure out is the proper settings. And before you figure out the proper settings, you’ll need to know which type of electrode to use. The type of electrode you want will depend on your base metals. Since 304 stainless steel is the most commonly used, we’ll be referencing that in all our examples. With 304 pieces of stainless steel, you’ll typically want to use 308L electrodes.
Once you’ve figured out which electrodes you’ll be using, you’ll be able to find the right amperage to use. An easy way to reference weld settings is by using either Miller’s or Lincoln’s free welding app.
When you’ve got your settings, one of the best ways to weld stainless steel is in a J-shaped motion. Because stainless steel and stainless steel rods heat up much quicker than normal, techniques like this help prevent the rod from crowning.
Once you’re done, clean off the excess slag with a chipping hammer and a wire brush.
Just like Stick welding, the first step to MIG welding stainless steel is finding the right parameters (easily done with this free welding app). Just as importantly, you’ll want to be using the right shielding gas. The best gas for stainless steel is a tri-mixture with 90% Argon, 7.5% Helium and 2.5% Oxygen. If that’s not possible, next best options would be 98% Argon and 2% CO2 or 98% Argon and 2% Oxygen.
The main problem with stainless steel and MIG welding is heat control. Because of the higher amperage you’ll have to use and the fact that stainless steel doesn’t dissipate heat as well as mild steel, it’s important to use all the necessary techniques to make sure your workpiece doesn’t become too hot.
Chromium is added to steel to give it that stainless quality. Often while TIG welding stainless steel, oxygen attacks the chromium. This can create oxides that can significantly reduce the lifespan of your weld. The secret is to get good coverage with your gas. While most welders tend to remember this with the front side of their welding piece, many forget to protect the back. If you’re welding two plates side by side, you’ll need to use a purging gas to keep oxygen from oxidizing the welds on the back of your pieces. If you have questions about purging, it’s a whole other subject you can learn more about in this post.
Whether it’s MIG, TIG, or Stick, if you’re having problems, it’s a 50% chance it’s from using improper parameters. If you’re sick of having to check references for every new welding project (and let’s face it, who wouldn’t be) you might want to try one of Miller’s fine auto-set machines. Now is one of the best times to be looking at a new welder with Miller’s Build with Blue promotion going on right now. It’s definitely worth checking out if you have yet.