low cost stainless steel for -80¦C application

[JMOwen]

I am currently evaluating the design of some large but lightly stressed welded storage frames. We have many years of experience of similar designs fabricated in mild steel (S275/43A) operating in a -20°C environment.

My concern is that that the new generation of frames will be in service at -80°C and must have a 25 year design life.

Brittle fracture is obviously the main concern. There is no stress cycling to speak of so fatigue is unlikely to be an issue.

As all ferritic steel appear to be fully brittle at -80°C, specifiying 304 stainless steel would solve the problem but adds significant cost.

Are there cheaper grades which are readily available in sheet and rolled hollow sections in the UK?

 

[mcguire]

There are such grades but the availability is the hard part.
Unless someone out there knows of something I don't, I would have to say ferritic and martensitics steels of any sort are out of the question. 304 is the right choice, I think, because the better choice, 201 probably won't be available in tube form unless custom ordered. You can probably find it in sheet.
Let's ask EdStainless why no one in the tubing industry makes 201 structural tubing. I know his company makes more sophisticated products than structurals, but there is a need, if not a developed market.

 

[EdStainless]

Because I can't get strip with the chemistry balanced to aid welding.
Even the duplex alloys are out.
What about Nitronic 30, it will have more strength than 304 and let you cut the thickneses.
I hate to say it but 304 may be your best bet. Could you use it a cold worked condition to get better strength?

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[stanweld]

2.5% Nickel alloy steels will fit your needs at -80C. Check with Arcelor with regard to product forms available.