Max FN for 316L and 304L
Max FN for 316L and 304L
(OP)
Hi All,
Despite reading many references on the net and in these forums I'm still confused about what maximum Ferrite Number I should specify for welds between 316L or 304L. This is for structural welding which will be in service at the coast. The electrodes being used are as pre-qualified (by AS 1554.6) for the alloys - i.e. 316L and 308L respectively.
General consensus is that you need a minimum of 3 or 4 to prevent cracking, but what about the upper limit? I have seen anything from 8 to 15 when reading different things. At what point does the ferrite content start significantly degrading corrosion resistance of the weld?
How does the recommended range change if you are doing a dissimilar weld to a structural steel?
Thanks,
Gemma
Despite reading many references on the net and in these forums I'm still confused about what maximum Ferrite Number I should specify for welds between 316L or 304L. This is for structural welding which will be in service at the coast. The electrodes being used are as pre-qualified (by AS 1554.6) for the alloys - i.e. 316L and 308L respectively.
General consensus is that you need a minimum of 3 or 4 to prevent cracking, but what about the upper limit? I have seen anything from 8 to 15 when reading different things. At what point does the ferrite content start significantly degrading corrosion resistance of the weld?
How does the recommended range change if you are doing a dissimilar weld to a structural steel?
Thanks,
Gemma





RE: Max FN for 316L and 304L
RE: Max FN for 316L and 304L
For high temp because it turns into sigma and gets very brittle.
Not for general as welded because there is no zone where you have enough to help with weld integrity and yet not too much for corrosion issues.
In SS that is annealed after welding there is often a limit of 0.5% in critical corrosion situations.
Don't worry about the max. It is more important to fist get sound welds.
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Plymouth Tube
RE: Max FN for 316L and 304L
RE: Max FN for 316L and 304L
I have encountered many ranges, but anywhere within 3 min. (not lower) and 10 max. (not higher) will suffice for general applications that are neither cryogenic nor high-temperature. The 308L deposits I have tested have not strayed much from 7-8FN.
RE: Max FN for 316L and 304L
RE: Max FN for 316L and 304L
brimstoner, where did you get your 10 max from? Is it experience or a reference? My fabricator is getting results of 9-12, which i'm inclined to accept, I was thinking about setting a range of 4 to 12 or 15.
RE: Max FN for 316L and 304L
RE: Max FN for 316L and 304L
Consumables for standard austenitic stainless steels are generally designed to result in a ferrite content of between
3 FN and 15 FN in the as-deposited fusion zone, for enhanced resistance to hot cracking.
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Max FN for 316L and 304L
RE: Max FN for 316L and 304L
When I was doing development work for SS overlay I noticed how consistent the Cr and Ni contents of ER309L were from various suppliers (of course there are more suppliers than actual manufacturers, which partly explains it).