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Need help with RAR abbreviation

Need help with RAR abbreviation

Need help with RAR abbreviation

(OP)
I have a part that is carburized SCM420H (similar to SAE 4120).  I have a report that states the case microstructure is "Tempered martensite RAR 1-2".  I need to know what RAR means.  I assume it is a retained austenite rating.  Any details about this would be appreciated.  Thank you for your help.

Regards,

Cory

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RE: Need help with RAR abbreviation

I am not familiar with the term - it does not appear in either of the two main gear metallurgy specifications AGMA 923 or ISO 6336-5.
What is the part?

RE: Need help with RAR abbreviation

(OP)
It is a tripod housing for a vehicle halfshaft.  I have "borrowed" an Internet image of a similar part, although the area of interest has been truncated (to the right) in this image:

Regards,

Cory

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RE: Need help with RAR abbreviation

It sounds like the RAR 1-2 refers to some internal company document from the OEM.

RE: Need help with RAR abbreviation

Cory:

metengr's link shows that lab uses RAR = to your guess.  Could it be a typo and should read RAR 1-2% instead of inches?

RE: Need help with RAR abbreviation

No - 1-2% is way too low a number for anybody to quote and it be meaningful even using X-ray diffraction.

RE: Need help with RAR abbreviation

(OP)
It was not 1-2 inches - I used the quotation marks to show an exact exerpt from the report.  Yet another reason to never use the inch-pound unit system.  Blech....

I think Carburize is correct - this is a rating according to an internal company specification.  By the way, it can't be the OEM - that's ME!  Now to comment to my supplier how much I think of their report that uses unexplained abbreviations, misspelled my company's name, etc.

Regards,

Cory

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RE: Need help with RAR abbreviation

Cory - let us know what it means when you find out!

RE: Need help with RAR abbreviation

A major thread drift but... is there any connection between cory and tvp?

RE: Need help with RAR abbreviation

(OP)
Yes.  How did you determine this? Small world, isn't it?

Regards,

Cory

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RE: Need help with RAR abbreviation

cory - I frequent the ASM  board as well - OK so what is the connection?

RE: Need help with RAR abbreviation

(OP)
I just visited our supplier.  RAR is an abbreviation for Retained Austenite Rating.  This rating is a visual comparison to images of microstructures with known retained austenite levels.  There are 7 levels, with 1 being low retained austenite (say < 10%), and 7 being high.  The information was attributed to "Chevrolet Laboratories, Detroit, Mich.".  There hasn't been a Chevrolet Laboratories in Detroit, Michigan for quite some time, so this is a legacy document that is not widespread in global industry.

Carburize - I prefer to limit public disclosure.  If you are an ASM member, you can access the ASM member database and contact me directly.

Regards,

Cory

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RE: Need help with RAR abbreviation

cory - no problem I fully understand -
Thanks for the information on the RAR - if only the lab had just put 10 - 15% on the report!

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