The number one tip for stainless steel welding is
maintain the stainless properties.
how do you do that?
There are a number of best practices you can put into place to prevent stainless steel from rusting or losing its stainless properties.
here are some common best practices
1. keep stainless away from carbon steel grinding dust
I have worked in a few fab shops where they went to great efforts to separate stainless steel work areas from carbon steel areas.
One shop even built a wall to separate the stainless area because they were having issues with carbon steel iron dust getting all over the stainless pipe and parts and causing corrosion issues.
2. use only clean stainless wire brushes on stainless. its good to dedicate stainless wire brushes and either color code them or write "stainless only" on them.
its also a good idea to dedicate files, carbide burrs, etc for stainless only.
3. the back side of fully penetrated stainless welds need a purge. Argon is usually the best choice for purge gas....
This is most easily done with a dual flowmeter or by having 2 separate argon cylinders.
pictured below is the SPARC dual flowmeter, you can see it on my store here
4. limit heat input to avoid carbide precipitation.
This one can be confusing.
when I say limit heat input, That does not always mean less amperage .
travel speed is one of the biggest factors....sometimes a faster travel speed can actually put less heat in a weld.
carbide precipitation is a time AND temperature issue.
Its obvious that in order to weld stainless steel, we have to reach the melting point.
but thats not the problem.
its how long the surrounding areas in the HAZ stay in an elevated temperature.
the longer stainless steel is held at an elevated temperature , the more likely carbide precipitation will occur...its not just amperage.
carbide precipitation and sugaring are two separate issues although they are often reffered to as the same thing.
you cant see carbide precipitation with the naked eye. its in the microstructure.
in essence, carbon particles precipitate/migrate to chromium particles and combine to form chromium carbides.
when that happens, it creates low chromium areas that corrode.
5. For TIG welding stainless, usually less amperage is needed than for carbon steel.
and I personally find that for sheet metal parts, one size lower filler metal than what I would normally use on carbon or 4130 helps.