304 + Molybdenum
304 + Moly + Titanium
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304 + Titanium
304 + Niobium
304 + Extra 2%Cr
304 + Extra 4%Cr + 4% Ni
All the above stainless steel grades are basic variations of a 304. All are readily weldable and all have matching consumables, except for a 304 which is welded with a 308 or 316, 321 is welded with a 347 (Titanium is not easily transferred across the arc) and a 316Ti is normally welded with a 318.
Molybdenum has the same effect on the microstructure as chrome, except that it gives better resistance to pitting corrosion. Therefore a 316 needs less chrome than a 304.
310
(24-26Cr,19-22Ni)
True Austenitic. This material does not transform to ferrite on cooling and therefore does not contain delta ferrite. It will not suffer sigma phase embrittlement but can be tricky to weld.
904L
(20Cr,25Ni,4.5Mo)
Super Austenitic Or Nickel alloy. Superior corrosion resistance providing they are welded carefully with low heat input (less than 1 kJ/mm recommended) and fast travel speeds with no weaving. Each run of weld should not be started until the metal temperature falls below 100°C. It is unlikely that a uniform distribution of alloy will be achieved throughout the weld (segregation), therefore this material should either be welded with an over-alloyed consumable such as a 625 or solution annealed after welding, if maximum corrosion resistance is required.
Stainless Steel testing 
Re: Stainless Steel testing
