AL-6XN vs. 316L Stainless

[Saltyhog]

Has anyone any experience using AL-6XN to replace 316L for components that get or stay wet with saltwater? I'm considering using this material for a bob-stay fitting that lives right at the waterline. Also potentially for chainplates. The numbers all point to better performance in all areas except price. I'm just not sure I want to be the one to blaze this trail. See: AL-6XN and This

[Jim Cate]

FWIW,

I recently pulled my 23 year old chainplates for inspection. They are made of 2205 duplex, and were in like new condition. Your prospective alloy is somewhat similar, but obviously not identical.

I'm pretty happy with the 2205...

Cheers,

Jim

[Weyalan]

2205 grade duplex stainless is an excellent choice, per the above poster. Aquamet 22 is also an excellent choice.

[Steel sails]

This alloy is a super stainless it's superior to 316 stainless in both corrosion resistance and strength. Approximately twice the strength of weldable 316 (316L) It's a good alternate to 316 for yor use. Great care needs to be taken when welding this material.
duplex stainless (2205) and super duplex stainless (2207) are IMHO better choices
We produce subsea oilfield equipment and super duplex is the preferred choice for critical offshore equipment
Regards Paul

[Saltyhog]

Originally Posted by Steel sails

This alloy is a super stainless it's superior to 316 stainless in both corrosion resistance and strength. Approximately twice the strength of weldable 316 (316L) It's a good alternate to 316 for yor use. Great care needs to be taken when welding this material.
duplex stainless (2205) and super duplex stainless (2207) are IMHO better choices
We produce subsea oilfield equipment and super duplex is the preferred choice for critical offshore equipment
Regards Paul

Interesting. The bob-stay fitting is a welded assembly. Are you saying the the AL-6XN is difficult to weld and that 2205 or 2207 is a better choice due to ease of welding? Are there any special considerations for welding 2207? I checked, and the yield and tensile strength are far superior to 316. So it may work well if: A) I can find a source and B) I can find someone to weld it.

[Steel sails]

If the AL6 is a manufactured part from a known manufacturer I wouldn't worry about it. If you intend to free issue the material to a weld shop I wouldn't,t go that route unless they had a weld procedure and the qualification record for it.
This isn't the forum to get into the technicalities of welding but the AL6 is temperature critical as it is usually welded with alloy 625( very expensive) filler metal and the 2 alloys have different melting points No. Problem for those who have developed a procedure.
Also note that AL6 should not be cut with traditional oxy fuel systems. Plasma or saw cut is recomended.
Duplex is much more readily available in Europe and the welding of it more commonly understood but less so in the US.
Regards
Paul