How to MIG Weld Stainless Steel?

MIG welding also known as GMAW is a common welding technique that has been used for quite some time. This welding process was used first in the production of weapons and other fighting equipment during World War II. Since then MIG has undergone improvements and developments, and it is currently common in the welding industry even when other numerous welding methods have crop up.

While getting knowledge on how to MIG weld stainless steel is more challenging than what we can jot down in a thousand words or more below is a summary of getting set to MIG weld stainless steel.

Getting set up For MIG Welding Stainless Steel

The first thing to do when MIG welding stainless steel is to establish the thickness of the metal. This is necessary because you will need the right shielding gas and welding wire. For this case wires available are 304 and 316 grades. For marine structures and corrosive areas use grade 316 wire. Also when MIG welding stainless steel instead of CO2 that is used in mild steel, 100% pure Argon gas is used in stainless steel.

The next thing to do is to set the speed of the feeder wire and the correct amperage. They should be set according to the thickness of the metal, the ticker the steel metal the more amps needed. Thickness of the in the machine will also determine the wire feed speed.

Stainless steel MIG welding process

The welder can start welding after the welding machine and gas supply is turned on. The welder will need a shield to keep the Argon gas on the weld area in case he/she is welding in outdoor conditions.

Turn on the power button in case you have an automatic welding mask. Lower the hood if using a manual helmet to get ready for the welding process. Remember to use a helmet that meets the set standards of NSIZ87.

The welding gun should be pointed at ten degrees to the welding line and held at an angle of 90 degrees to the welding area. Then the trigger on the MIG gun is squeezed. Move slowly up the welding line once the process begins. Make sure at the weld zone you have a pool of molten metal.

MIG Welding Techniques for Stainless Steel

The techniques applied in welding nickel-based alloys and stainless steel are almost similar to those used in carbon steel. Three basic factors should be taken into consideration when MIG welding stainless steel:

Transfer Type

When it comes to transfer type when welding stainless steel, it is either spray transfer or globular. Spray transfer is best because of the high percentage of Argon which produces an arc of hot fluid which is ideal for this kind of transfer. The only difference between globular and spray transfer is that in globular globs form from the electrode and drop into the weld joints. All these transfer types work for stainless steel but most welders prefer spray transfer especially on thick metals.

Distortion

Inter-pass cooling and bracing should be used to control distortion. To restrain the joints, bracing is used. Stainless steel keeps heat for some time, hence as the welds cool the joints will start moving. Inter-pass cooling is used to let the joints cool before another weld is started.

Welding Techniques

The techniques applied in welding nickel-based alloys and stainless steel are almost similar to those used in carbon steel. For stainless steel metal, the actual techniques used are weaving, whipping, and circles. All these techniques work best depending on the type of joint and position. To avoid massive distortion use stringer beads instead of wide weaves.

Conclusion

MIG welding calls for a lot of attention and focus, MIG welders when doing this process cannot multitask. Furthermore, the bottle holding the shielding gas must be big hence, it can be a burden to some welders. MIG welding does not work best with paint, dirty surfaces, and rust. Also purchasing consumable parts like tips and nozzles may be expensive. However, it is necessary to remember that MIG welding is the most preferred welding process when it comes to welding thin metals like stainless steel metal sheets.

There are numerous welding methods that you can use to get what you want. All the processes are almost similar to what you only need is to choose the one that best suits your needs and use the right equipment.

FAQ’s

What is the correct shielding gas for MIG welding stainless steel?

The most recommended shielding gas for MIG welding stainless steel is a mixture of three gases, they include: 2.5% CO2, 90% He, and 7.5% Ar. Helium aids in providing good fusion into the base plate and also helps create a flatter weld bead because of its thermal conductivity is high.

What is the best way to weld stainless steel?

Choosing the best process for the job and using the recommended equipment is all you need to weld stainless steel. Arc or MIG process is the best way to welding method to use especially for basic welding. However, for high quality finishes for instance those used in the food industry TIG welding is the best option.

How do you tack weld stainless steel?

• Ensure that there is no gap completely by making tight the fit-up.
• Use a sharp tungsten electrode tip of less than 1/16” to prop your TIC cup into the joint.
• Set the Tungsten Inert Gas welder to hit fast and hot when the foot pedal or press switch is pressed.
• Start the process immediately you hit the torch switch or foot pedal.

Do you need special wire to weld stainless steel?

Yes, a special wire is required. 045-inch wire is recommended. Also the most recommended shielding gas for MIG welding stainless steel is a mixture of three gases, they include: 2.5% CO2, 90% He, and 7.5% Ar.

Can Stainless be MIG welded?

Stainless steel can be MIG welded. All you need is to choose the best process for the job and using the recommended equipment is all you need to weld stainless steel