Austenitic Stainless Steels

The most common form of stainless steel used in industry is the austenitic range of stainless steels. 308L, 316L, 309 and 347 grades of Stainless TIG filler rods are the most commonly used to welding these stainless steels. Please see below in-depth technical support and guidance on which Stainless Steel filler wire grade is the best to use for each corresponding parent material.

Guidance on what TIG filler rod to use on Austenitic stainless steels

What are Austenitic Stainless Steels?

18-8 type stainless engineering steels have the designation 300 series and the most common alloys are the 301, 302, 303 & 304 grades which are referred to as austenitic stainless steels, since their crystal lattice structure in metallurgically known as face-centred cubic (fcc).

What TIG welding rod do I use for these austenitic grade stainless steels

301, 302 & 304 grade stainless steels are welded using 308L filler rod . No matching chemistry welding wire is produced. 308L welding rod contains 2% extra chromium content in order to counter the 2% Cr that is lost in the welding arc. Thus, the weld deposit then ends up as type 304. Carbon content may form chromium carbides and denude the grains of chromium. This reaction occurs at grain boundaries and can lead to localised severe corrosion. To counter this liability, stainless austenitic alloys have a controlled low carbon content. This can be further protected with an addition of titanium in type 321 or an addition of niobium in type 347. Since 60-70 % of the added titanium can be lost in the welding arc, usually type 321 alloy is welded using 347 welding wire. The suffix L is used to denote a carbon content usually of less than 300ppm (0.03%)

304 grade stainless steel can be protected for pitting and general corrosion by an addition of molybdenum at around 2.5% .This version is designated 316 or 316L TIG Rod

Welding with 347 filler rod can sometimes be susceptible to liquation-cracking and/or centre-line cracking. To minimise this susceptibility the welding wire chemistry is adjusted to produce 3-7% delta ferrite in the weld deposit. The islands of delta ferrite absorb carbon and tramp elements within the centre of the austenite grains and thus leave clean grain boundaries.

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