Welding Stainless Steel

What are the best techniques for welding stainlessaviation industries are a bit more varied. There are
steel? That's like asking whats the best way to golots of them. Austenitic stainless steels like 321, 347,
fishing? It depends on a lot of things, doesn't it? Lots316, and 304 are common, but so are martensitic
of things like what type of stainless, what thickness,stainless grades like 410 steel , Greek Ascoloy, and
whats the application, and for what industry?Jethete M190. Another family of stainless used on
Lets focus on three industries:commercial aircraft is the Precipitation Hardening
Food service, Aerospace, and Nuclear.variety. A PH at the end like 15-5ph, 17-4ph, 15-7ph,
1. Food Service17-7ph indicates that the steel is precipitation
Most stainless steel in the food service industry ishardening. That means holding it at high temperature
300 series stainless. Type 304 .063" thick stainlessfor extended time allows the steel to harden. PH
sheet metal to be exact. If you go to any Fast foodgrades are sometimes much more difficult to weld
counter and check out all the counters, shelving,than the straight 300 series because of alloy
cookers and such, you will notice it is all made fromelements and complex metallurgical reactions to heat
welded stainless steel sheet metal. Food servicewhile welding.
codes require 304 stainless steel to be utilized in foodTig Welding and automated plasma welding are the
preparation areas because it does not rust easily. Allmost commonly utilized processes.
welds are supposed to be performed in such a wayTips for Aerospace tig welding SS : Clean, Clean,
to not trap bacteria and other crud. Back sides ofClean. Use as big a tig cup and possible 3/4 " --1". Use
stainless steel welds should be shielded with argon sominimal heat and use any means to prevent distortion
that they are not sugared and full of pits that could(skip welding, fixturing, small beads) shield the back
trap bacteria like salmonella. All wire brushing shouldside of everything you weld with argon using tooling,
be done with a stainless steel brush and welds thator home made purge boxes.
are not perfectly smooth should be blended smooth3. Nuclear
with some type of abrasive wheel and then cleanedNuclear piping systems use a lot of stainless steel and
with alcohol.most of it is TIG welded. Or at least the root pass is
Tig welding is almost always the best process sincetig welded. Most of the stainless piping is basic 304L
spatter and slag are absent. Tig welding rods shouldstainless but other grades like 316 are used also. Tig
be 308L for welding 304 stainless. L is for low carbonroot passes with stick fill is pretty common with
becauseheavy wall pipe but anything under schedule 80 is
Carbon is bad when it comes to corrosion resistanceusually just Tig welded all the way out because x ray
in stainless.results are better that way. Stick welding is kind of
Tips for welding SS sheet metal : 1 amp per 1hard with stainless.
thousands of thickness, keep the hot tip of the fillerInstrumentation lines that are 1/2" and less in
rod shielded and snip it if it gets oxidized, use chilldiameter and are often done with orbital tig welding
bars made of aluminum, copper, or bronze wheneverbecause it is so repeatable. Welding small diameter
possible. Filler rod should generally not be bigger thantubing manually is tough.
thickness of metal welded. Keep bead width toThere are all kinds of other applications for welding
around 4 times the thickness of the sheet. Use a gascorrosion resistant alloys like boat propellers, headers
lens style cup, a #7 or bigger. A 1/16 thoriated orand exhaust, and marine hardware like sailboat parts.
lanthanated electrode will easily weld 16 ga .063"One thing to remember is that they distort easily so
sheet. Keep electrodes clean and sharp.precautions like heat sinks, chill blocks, and minimizing
2. Aerospaceheat input are all important techniques to use.
Stainless steel alloys used in the aerospace and