ASTM A-194 24-Hour Hardness Test

[QAFitz]

I'm looking for information on the origins and/or perceived benefit of the 24-hour hardness test in A-194 for most of the quenched and tempered nuts. I seem to remember that this was a method of validating the heat treat (i.e., the quench was performed and that the temper was done at/above the minimum required tempering temp.).
Any info would be appreciated. Thanks in advance for your time. Happy New Year.

 

[metengr]

QAFitz;
I have a copy of SA 194 (identical to ASTM A 194 except editorial differences in Tables 1 and 4), and I see no such requirement for a 24 hour hardness test. There are hardness tests required for the specific grades, but no such time limit. Where exactly did you see this requirement?

 

[Billybaru]

I know there is a requirement for the 24 hour heating of ASTM A194 Grade 2H nuts at a specific temperature and then hardness testing of the sample. This test is essentially a temper audit to assure the minimum tempering temperature was met.

 

[CoryPad]

I believe the question is in reference to section 7.1.5 of ASTM A 194/A 194M:

7.1.5 Test 2—In addition to the testing required by 7.1.2.1 the manufacturer shall also perform hardness tests on sample nuts after the following test heat treatment. After completion of all production heat treatments heat the specimen nuts to the temperatures indicated below for 24 h, then slow cool. Test at
room temperature.

Regards,

Cory

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

 

[QAFitz]

The paragraph reference by CoryPad (depending on the year of the Standard) is correct (in the '07 Standard its 8.1.5 and Table 2). The Grades requiring this test are Grades 1, 2, 2H, 3, 4, 7 and 16.
Billybaru mirrored what I've heard in that its a audit (verification) that the temper was performed correctly.
I've researched as far back the 1969 version of A-194 and cannot locate any rationale in the Standard as to why the test is required. This is what I'm looking for, the rationale behind the test.
Again, thanks for your input.