Standard Names For Stainless Steel 5

[Cristodul]

Hi everybody
Can anybody tell me if there is a standard on how to call a stainless steel?
For example what is the difference if I call 316 SS or UNS S31600?

 

[unclesyd]

As you stated in your post one had pedigree, UNS S31600 and the other, 316 SS is generic.

The UNS S31600 material has to conform to a definite set of parameters. The main one being the limits on chemistry.

316 SS can be any material that conforms to a generally accepted norm for the chemistry of a material called 316 SS. The chemistry is not controlled as it would be in the UNS S31600.

If there is any criticality in the end use of the material it is always best to call out the material under some
specification or standard.

 

[EdStainless]

If you said ASTM A240 316, then that would work also. Without a spec you are at risk.
I prefer UNS numbers (along with a spec). Their chemistries never change and they are listed in most specification. There is also a UNS for every alloy, even ones that don't have accepted common names. It is a way to help get the material that you expect.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[unclesyd]

One thing I didn't mention is that the UNS naming/numbering system is a kind of universal translator among the multitude of world specifications and standards. You can usually find and cross reference the UNS Number.

There is no easy path to understanding and applying the specifications and standards.

 

[mshimko]

If you want a specification type nomenclature, the above give good advice.

If you want a "generic" term that's easier to read an write (assuming you call out or reference the specifics, if necessary), I've seen:both of the following

SS 316,
CRES 316 [for Corrosion REsistent Steel]

 

[MatieMan]

More info you can find in a part of a CASTI handbook, free available on the net.

http://www.casti.ca/books_ebooks/lite/BlackBookNALite.pdf

 

[prohammy]

MatieMan,

Nice pdf, any equiv's for Europe


Kevin Hammond

Mechanical Design Engineer
Derbyshire, UK

 

[Cristodul]

Thank you all for helping me out...
I was out for couple days and today I saw how many replies I've got
I'm a little bit confused now. I've read on the internet the following:
"Instructions: The UNS number (short for "Unified Numbering System for Metals and Alloys") is a systematic scheme in which each metal is designated by a letter followed by five numbers. It is a composition-based system of commercial materials and does not guarantee any performance specifications or exact composition with impurity limits. Other nomenclature systems have been incorporated into the UNS numbering system to minimize confusion. For example, Aluminum 6061 (AA6061) becomes UNS A96061." (

http://www.matweb.com/search/searchUNS.asp)

So if this is stated like that how do I know what I'm getting?

 

[EdStainless]

A UNS number assures you of a composition range, not any other characteristics.
You must also specify a product specification (ASTM or EN or what ever) that has the other property requirements for you product.
As an example, if you asked for 316 bar I could send you any chemistry that is sort of close to 316, but with no firm limits, and any mechanical properties (hot finished, cold finished, and so on).
Now, if you said ASTM A276 S31603 you would have defined the chemistry, mechanical properties, and testing for you bar.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[Cristodul]

Got it!

Thank you much!

 

[bobble293]

Hi, lots of useful info here, especially from EdStainless. If only it were so easy this side of the pond.

I'm looking to source the following:-

Cold drawn SEAMLESS stainless tube 1) 1/2" O.D. x 16 SWG., and 2) 5/16" O.D. x greatest wall thickness available, for rigidity. This is for a low pressure hydraulic application (30 bar/450 psi)Water is the hydraulic medium. The larger tube is to be the cylinder, and the smaller to be the piston rod. The larger tube bore and external surface finish to be within the range 16 to 6 microinch, the smaller tube external surface to be within this range. Alternatively, mill finish should be close enough for the required finish to be readily achievable. "O" ring seals are to be run on these surfaces. Piston rod and cylinder will each be around 18" long, so suggestions as to how the required bore can be finished, if necessary, would be most welcome.
I used to finish long injection moulder nozzles with abrasive tape on a brass rod, but they were high value items, and I have to get these tubes down to a price. ASTM 269 316L has been suggested. One tube will have attachments silver brazed each end, the other will be flared one end, and have an attachment silver brazed at the other.

Any help in regard to sourcing would be appreciated, even if the source is U.S. based.

 

[EdStainless]

Why seamless? Trent supplies cold draw welded tubing for may pneumatic and fluid power applications. The as drawn surface finish is better than 25 miroinch.
Want to talk?

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[bobble293]

Hi,EdStainless, unexpectedly quick response! The reason I consider seamless necessary for the larger tube, at least, is because of the longitudinal weld bead on the inside. It'll have an "O" ring or "X2" ring piston seal running inside it. Less of an issue for the smaller diameter tube where there will only be an "O" ring or "X2" ring working on its O.D. so in that case ERW or similar would work, assuming the O.D. arrives with a surface roughness between 16 and 6 microinch, or close enough to finish cheaply. Longitudinally welded, or spirally welded tube still has the weld bead on the inside, doesn't it? I understand tubes greater than 1.5" now can be supplied with the bead dressed off, but this one's only .375" bore. For the product I'm developing to sell, I've got to meet a price point of $240 (£120) and there are a number of other component parts to this assembly. I may end up going to brass tube for both components, but that will have a downside in respect of robustness.
Any help would be appreciated.
Bobble.

 

[EdStainless]

Bob, have you ever seen an air (pneumatic) cylinder (Bimba, Festo, SMC) with a stainless body? They are welded and drawn tubing.
What exact ID size and tolerance do you need on the 1/2" tube?
ed

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[JamesCKelly]

Mr. Bobble you might want to take care when silver brazing stainless tubing. Torch brazing tends to crack the stainless, by liquid metal embrittlement, the source of stress being local thermal expansion caused by the braze torch. Play the torch back & forth either side of the joint. E.g., heat up maybe a 6" area on either side of the joint to minimize local thermal stress.