How to Weld Stainless Steel

There are 3 common ways to learn how to weld Stainless Steel Electrodes. SMAW (shielded metal arc) or stick welding, GMAW, commonly known as Mig welding (metal inert gas), and GTAW (tungsten inert gas) or Tig welding.

Stick or Arc welding

The methods to stainless using an arc welder differ little to that of welding mild steel. Generally, a gauge stainless steel electrode is used for arc welding Stainless Steel Electrodes. A safety note of caution, like mild steel there is a coating of slag left on a completed bead, with steel that the slag needs chipping off, however stainless slag has a propensity to 'ping' off as it cools. This can cause serious eye damage always wear eye protection using stainless electrodes. Using an arc machine is a relatively easy way to learn how to weld stainless steel.

Mig welding stainless steel

Again, a similar process used on steel. Obviously, you will need to exchange the mig welding wire for stainless steel wire. This is normally available in 304 and 316 grades. Use 316 grade stainless wires in high corrosion areas and for marine applications. You will also need to use pure gas instead of c02 which is used for mild steel. Mig welding is common in metal fabrication shops.

How to Tig Stainless

This method is the most difficult to learn how to weld Stainless Steel Welding, however in my opinion it is by far the most satisfying and offers a pure joint between base metal and filler metal.

Using a tig requires more skill but in a way, is like using the Oxy-Acetylene gas process. Tig welders use a little hand-held torch that carries a tungsten electrode to create the arc. Tungsten is used as it has an extremely high melting point. The tungsten tip, when struck into the metal creates the arc and begins the fusion process; at this point a filler rod is introduced to add substance to the joint. This is where the operator needs a steady hand.

Learning how to weld Stainless Steel Welding comes down to using the correct equipment and choosing the best process for the job. For basic welding of stainless the arc or mig process will suffice, however if you need a quality finish or are constructing a product that requires a clean finish such as a commercial food mixing component the tig welder is the way to go. As with everything using the correct process and practice will get you to expert status in no time.

Stainless Steel Welding Electrodes

What are the best techniques for Stainless Steel Welding? That's like asking what’s the best way to go fishing? It depends upon a great deal of things, does not it? A great deal of things like what type of stainless, what thickness, what’s the application, and for what industry?

Let’s focus on three industries:

Food service, Aerospace, and Nuclear.

1. Food Service

Most stainless steel in the food service industry is 300 series stainless. Type 304 .063" thick stainless steel to be exact. If you go to any Fast food counter and check out each of the counters, shelving, cookers and such, you will notice it is made from welded stainless steel sheet metal. Food service codes demand 304 Stainless Steel Welding to be used in food preparation areas because it does not rust easily. All welds are supposed to be performed in such a way to not trap bacteria and other crud. Back sides of stainless steel welds must be guarded with argon so that they are not sugared and full of pits that could trap bacteria such as salmonella. All wire brushing should be done with a stainless steel brush and welds which are not perfectly smooth should be blended smooth with some type of abrasive wheel and then cleaned with alcohol.

 

2. Aerospace

Stainless steel alloys used in the aerospace and aviation industries are varied. There are tons of them. Austenitic stainless steels such as 321, 347, 316, and 304 are common, but so are martensitic stainless grades like 410 steel Ascoloy, and Jethete M190. Another family of stainless used on commercial aircraft is the Precipitation Hardening variety. A PH in the end such as 17-4ph 17-7ph indicates that the steel is precipitation hardening. That means holding it in high temperatures for extended time allows the steel to liquefy. PH grades are sometimes much more difficult to weld than the right 300 series because of alloy elements and complex metallurgical reactions to Stainless Steel Electrodes.

3. Nuclear

Nuclear piping systems use a whole lot of stainless steel and the majority of it is TIG welded. Or at least the root pass is tag welded. Most of the stainless piping is basic 304L stainless steel but other grades like 316 are used also. Tag root passes with stick fill is pretty common with heavy wall socket but anything beneath schedule 80 is usually just Tag welded all the way out because x beam results are much better that way. Stick welding is kind of difficult with stainless.

There are all kinds of other applications for welding corrosion resistant alloys like boat propellers, headers and exhaust, and marine components such as parts. One thing to remember is that they distort easily so precautions such as heat sinks, chill blocks, and minimizing heat input are all techniques to use.