Need some simple clarification regarding the rockwell (HRC) test

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cliff_B07
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Joined: Tue Apr 12, 2016 1:50 pm
Location: Toronto

Need some simple clarification regarding the rockwell (HRC) test

#1

Post by cliff_B07 »

I have been searching this subject but cant seem to find a simple straight forward answer to my questions.

So here it goes:

So before starting the test the diamond identor rests on the steel with 330 pounds of pressure. Then the test starts by adding more pressure above the 330 pounds.

So once the indentor penetrates the steel that marks the HRC hardness? Is HRC measured in pounds over the initial 330 pounds?

For example zdp 189 has a HRC of 64, does that equate to 330 lbs + 64 lbs = Indentation ? (a total of 394 pounds to indent zdp 189)

Would anybody like to explain this to me?

Thanks
Eli Chaps
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Joined: Fri Feb 03, 2017 9:56 am

Re: Need some simple clarification regarding the rockwell (HRC) test

#2

Post by Eli Chaps »

I don't think so.

I believe the way it works is based off the depth of penetration of a given (set, known) amount of force. That depth is then plugged into the appropriate scale equation to achieve a number. The resulting number itself e.g. 64 is meaningless outside comparisons to the same scale. In other words, an HRC of 64 only has meaning when comparing to other HRC results. HRC 64 is harder than HRC 59 but HRC 64 compared to some other hardness test method wouldn't mean anything. "64" is just a unit of measure not an actual measurement.
cliff_B07
Member
Posts: 13
Joined: Tue Apr 12, 2016 1:50 pm
Location: Toronto

Re: Need some simple clarification regarding the rockwell (HRC) test

#3

Post by cliff_B07 »

Thanks Eli

I understand what your saying.

So depth of penetration at accumulated force somehow equates to the hrc number.

Anybody know what the formula is in order to get the hrc number?
Eli Chaps
Member
Posts: 767
Joined: Fri Feb 03, 2017 9:56 am

Re: Need some simple clarification regarding the rockwell (HRC) test

#4

Post by Eli Chaps »

cliff_B07 wrote:Thanks Eli

I understand what your saying.

So depth of penetration at accumulated force somehow equates to the hrc number.

Anybody know what the formula is in order to get the hrc number?
Do a Google search. The Wikipedia page has the formula and the scale inputs.
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