We often get asked if metals other than mild steel can be welded with a MIG welder. The most common materials we’re asked about are aluminum and stainless steel since they are also regularly used for automotive restorations and custom jobs.
Here, we’re tackling this question as it relates to stainless steel. So can stainless steel be welded by a MIG welder? The short answer is that as long as you’re using the correct consumables and accessories, you can MIG weld stainless steel in most cases. Below, we give some information about welding stainless steel with a MIG, including other questions to ask before starting and which consumables you should order.
- Is it Stainless Steel or a Coating? —The first thing to look at is whether you’re working with genuine stainless steel. Oftentimes, coatings are put over steel to give an appearance of stainless steel, and this can fool a lot of people. True stainless steel won’t be magnetic, so you can test with a common magnet on the surface. If the magnet sticks, it is mostly mild steel and regular MIG welding techniques and tips will apply. if the magnet doesn’t stick, you’re dealing with stainless steel or another type of metal.
- Welding Stainless Steel with a MIG — Any MIG welder that can weld mild steel can also weld stainless steel. We suggest only using a true MIG welder and not a flux core welder (or a MIG in flux core mode), as the shielding gas is very important when welding stainless.
- Which Welding Wire? — A little-known fact is that you can MIG weld stainless steel with the same mild steel MIG wire you use regularly. However, the problem is that the weld will now rust and needs to be coated to stop rust. Because of this, we suggest switching to a stainless MIG wire.
- Use a Spool Gun — If you have a MIG spool gun, you can keep your wire in your welder and switch out the stainless wire to the spool gun to save downtime on the welder. Load it up and set the machine as you would normally.
- Back Purge — If you’re welding stainless tubing, we suggest looking into purging the backside of the tubing when welding to avoid contamination to the weld. This can be done with something as simple as a hose fitting T and some tin foil with a hose run inside the tubing to fill it with welding gas as you’re welding.
- Shielding Gas — Gas selection and flow are crucial for MIG welding stainless. Generally, either pure argon gas or a blend of argon and minor gases will do a decent enough job. However, there are also special stainless shielding gas mixes formulated for this more exotic steel. The process also requires a higher gas flow than mild steel welding. The recommended flow rate for most stainless projects is 14-16 liters per minute.
- TIG Welding Stainless Steel — If you’re doing a lot of stainless steel welding, consider switching to a TIG welder for those jobs. A MIG welder works well for occasional stainless repair, but it tends to be a messier finish and isn’t as controlled on thinner gauge metal.
Most welding supply stores will carry or can order stainless MIG wire. You should try and match your filler wire as closely as you can to the type of stainless that you’re welding. To see our entire line of MIG welders and accessories visit Eastwood.com today. Our experts are also available for assistance seven days a week by phone, email or in-store. Eastwood is a DIY welding pioneer and has been helping people Do the Job Right since 1978. View our MIG Welding Videos and Articles for even more tips and tricks.