The "R" designation in 316R

[Deformationman]

I am trying to figure out what the "R" designation is for a fastener stating it's 316R. I would appreciate any help to shed some light on this? I've looked on the web and several books and cannot find the exact "R" processing and chemistry requirements.

Thanks in advance for your help!

Wilson Silverthorne

 

[unclesyd]

I do a little work for a fastener company and have checked with several manufactures of s/s fasteners and none have any clue as to the meaning of the "R". There is an ASTM spec that uses an "R" suffix, but it is for carbon and alloy sreels. The spec is ASTM A400-69(2000).
Is there any other reference to the material other than "316R"?

 

[Deformationman]

Thanks unclesyd for the quick response. I've had about as much luck too.

The entire material designation is:

SS-316-R Austenitic Stainless Steel per MPIF STD NO.35.

I do not have access to MPIF STD 35 but it is supposed to be equivalent to ASTM B883 which does not list 316R? I have a call into the supplier of this fastener and they have not been able to give a good answer either. I'm starting to wonder if it's a typo. But, I found a research paper on the internet that references a 316R as a standard grade of 316. What a mystery.. ha ha

Thanks again for the help.

Wilson

 

[Carburize]

One site I found in England listed one of their products as being available in "food-grade" 316R???

 

[Carburize]

http://www.unisonmetals.com.tw/ugine/ugine-1e.html

Lists the grade but simply says that it is equivalent to 316.

 

[Deformationman]

Carburize,

thanks for the leads. I found the food grade reference too? I also found a Precision Metals Service that has an internal spec PMS 316R. I'm now trying to find out where my supplier got their raw material. The excitement never ends? Thanks again for your input!

Wilson

 

[TVP]

FYI, MPIF Standard 35 is a powder metal specification -- Materials Standards For P/M Structural Parts published by the Metal Powder Industries Federation. I have the 1994 edition (this is not the most recent revision) and 316R is not a grade that is listed.

 

[Maui]

The R in 316R likely stands for Republic. Republic Steel used process several grades of steel that were variations on the 316 chemistry. Other variations included 316LR and 316LLR.


Maui

 

[Deformationman]

Thanks, TVP and maui

I'm still awaiting the supplier to call with hopefully an answer. Glad to see I wasn't the only one confused. Thanks for checking the MPIF #35, since I didn't have access to that spec you've answered an important question. It's seeming like, as was suggested by TVP, this may be a company designated "R". Thanks again for all your input. This is my first post to this site, and I'm very impressed!

Thanks

Wilson

 

[CoryPad]

Why would a fastener use powder metal? I can't think of any applications that currently use powder metal...


Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[aviteri]

See INCHAURZA's book but it's in spanish

 

[arunmrao]

We have a company in India TVS fasteners who manufacture by P/M route their fasteners and US auto industry is their biggest customer.Though like CoryPad I too have been wondering for the past 20 years about this technology

 

[Deformationman]

Thanks to everyone who responded to this question. I haven't arrived at a concrete answer other than to assume it's an internal company designation. Precision Metal Services has a 316R as a subset of 316 alloys. Anyhow, I have released the lockring due to it's application and the fact that it does meet the chemistry spec for 316. So again I appreciate everyone's input and I hope I can help one of you someday in return.

Best Regards

Wilson Silverthorne

 

[Lovison]

Corypad,

Years ago I mean at least 35 years ago - I once worked for a nut and bolt company that made hardware from powder. I think the material was a brass or bronze nut/bolt. I was surprised too when I got there. I loved that job so much I quit after two weeks.

wlovison@toyopumps.com

 

[Powderman]

Hi everyone

The "R" designation in SS-316-R is a 15 year old designation from the MPIF standard 35. The R refers to the sintered material density, in this case 6.4-6.8g/cc. Most powder metal parts have some porosity which reduces the metals density from the theoretical density of wrought material (in the case of 316 the theoretical is approx 7.9g/cc).

There is no current equivalent standard to the old R standard but the closest match for a fastener application is probably SS-316N2-33.

Hope this helps