Hight strength stainless steel for cryogenic application

[jclsws]

I am looking for a high strength stainless steel to use for tension rods. The environment is cryogenic, so the material should be austenitic. Standard 304 and 316 grades do not have the strength I need to keep the number of rods to a minimum. I have been looking at XM-19, but it seems to be pretty expensive. Is there a lower cost high strength austenitic stainless steel with a similar yield strength? The rods will be round stock threaded at both ends.
Thanks.

 

[EdStainless]

You should look at some of the other Nitronic grades.
Unless you need the higher corrosion resistance of XM-19 I would suggest 21-6-9, S21904, XM-11 as my first choice.
With a little cold work you can get 125ksi UTS.
I'll hunt for low temp properties on the cold worked material.

Data at low temp on annealed material is commonly available.
It may be strong enough for you.

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Plymouth Tube

 

[SnTMan]

jclsws, had to buy some XM-19 for pressure vessel bolting recently. YOW!

Regards,

Mike

 

[jclsws]

EdStainless, corrosion resistance is not a really big deal. I need the strength and low temperature ductility. I will investigate XM-11 a little further and see if I can source some. Thanks for the guidance.

 

[TVP]

jclsws,

What kind of strength level do you need? Annealed 304 and 316 are low strength, but both can be cold worked to considerably higher strength. B8 (304) Class 2 and B8M (316) Class 2 according to ASTM A320 are cold worked to minimum yield strength of 100 ksi for sizes < 3/4".

 

[jclsws]

TVP, ASTM A320 is another possibilty. It certainly meets my strength requirements, and I'm sure it's lower cost than the Nitronic alloys. It will probably come down to a matter of sourcing.

 

[jclsws]

I'm assuming that the 300 stainless steels retain their low temperature ductility when cold worked to A320.

 

[jwhit]

The best low temperature properties are found in the fully solution annealed condition. Residual ferrite can affect low temperature ductility, though I'd think toughness still remains better than most other materials. My background is castings where ferrite is an issue for use at low temps. I'm not totally sure about the martensite formed in cold working, but suspect it could also be an issue.
Jeff

 

[EdStainless]

The last post is right.
A 304 or 316 that becomes magnetic when cold worked will have reduced toughness at low temperatures.
21-6-9 will stay fully austenitic at 160ksi and has nice properties.

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Plymouth Tube

 

[jclsws]

Thanks for the info. I think I'd rather have something I'm comfortable with than go low cost and take a chance. This is a somewhat specialized application, so the end product is not going to be cheap to start with. I'll see if our materials purchaser can source some XM-11 bars.