Question about test block for ASTM E18
Question about test block for ASTM E18
(OP)
Recently I got my Rockwell hardness testing machine calibrated. The guy from the calibration service told me that ASTM E18 is a new standard for this test and I will have to buy new B-scale tungsten balls and appropriate test block for the future use. Could anyone please tell me what exactly do I need to buy? My current B-scale test block has a Mean Hardness Value of 96.69 and I am wondering if I can still use it for the new E18 standard! Thanks.





RE: Question about test block for ASTM E18
from Notes 2 & 3 (available in the on-line, free abstract!).
"The National Institute of Standards and Technology (NIST) maintains the national Rockwell hardness standards for the United States. In June 1998, NIST released new Rockwell C scale (HRC) test blocks as Standard Reference Materials (SRMs). The blocks were calibrated using NIST's primary reference standardizing machine...
...The revision of E 18 requires that all performance verifications of Rockwell hardness indenters and hardness machines must be made using test blocks calibrated traceable to the Rockwell standards maintained by NIST...
...steel and tungsten carbide balls have been shown to give different results. For example, depending on the material tested and its hardness level, Rockwell B scale tests using a tungsten carbide ball indenter have given results up to one Rockwell point lower than when a steel ball indenter is used."
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See also NIST Special Publication 960-5 Rockwell Hardness Measurement of Metallic Materials.
h
(from CoryPad in thread330-141635)
RE: Question about test block for ASTM E18
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RE: Question about test block for ASTM E18
My question is, if NIST blocks are used for the annual calibration are the cheaper non-NIST reference blocks suitable for routine verification? The last time I read E-18 it gave me the impression that the NIST blocks were available, but not required to be used. I'll admit, this was a few years ago and we do not "ceritfy" our test results, but I'd like to know if ASTM requires NIST test blocks be used.
rp
RE: Question about test block for ASTM E18
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Question about test block for ASTM E18
RE: Question about test block for ASTM E18
RE: Question about test block for ASTM E18
RE: Question about test block for ASTM E18
One of the biggest problems I've seen with hardness testing is the sample preperation, things like using the first reading taken on the sample, and not accounting for round stock.
RE: Question about test block for ASTM E18
RE: Question about test block for ASTM E18
Sorry it took so long to get back to you, broken computer.
The majority of our blocks are either the Wilson or Yamamoto supplied by Wilson Instruments. The ranges are much larger than the 0.1 point you mention.
I can see a lot of problems if someone without the knowledge of the inhomogeneity of metals calling a specification of 58 Rc +/- 0.2.