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zatau
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Join Date: Oct 2008
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Measurement Unit for Charpy V Notch Impact Test

03/10/2013 1:26 AM

As per the technical specification of a generator shaft, specification specifies that - " individual values of Charpy V Notch impact test shall not be less than 3.5 daj/sq cm ".

What does 3.5 daj / sq cm indicates ?. Is it deca joule per squre centimeter ?.

What area to be taken into considerartion to convert it to the Joule ?. Is it the standard test sample cross section area (10 mm X 10 mm as per ASTM-370) ?. Generally test results for Charpy V Notch Impact tests is reported in the energy unit Joule.
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lyn
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#1

Re: Measurement Unit for Charpy V Notch Impact Test

03/10/2013 12:28 PM

1 dja = .1 joule.

I am not familiar enough with Charpy testing to comment further.
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MJCronin
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#2

Re: Measurement Unit for Charpy V Notch Impact Test

03/10/2013 2:24 PM

Zazu....

This ancient (113 year old)ductility test is meant to empirically detect the brittle transition temperature for a particular metallic specimen. Results are in units of energy FOR A PARTICULAR SIZE OF SPECIMEN.

Look up the standard specimen size on Wikipedia and in ASTM 370.

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Lehman57
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#3

Re: Measurement Unit for Charpy V Notch Impact Test

03/10/2013 11:16 PM

When I did some of this 30 some years ago the units we used were ft-lb @ temperature. In our case most wanted at least 15 ft-lb @ -20 degrees. The specimens were a standard size.

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Javier Aseguinolaza
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#6
In reply to #3

Re: Measurement Unit for Charpy V Notch Impact Test

03/11/2013 5:56 AM

The units are important, check the evaluation/comparable values are the same units, there are two terms or specifications resulting from this test, temperature at which the test is done, usually -20, -30, -40, -50 ºC (or equivalent in other units like ºF), and Joules obtained as a result (energy). there are normalized test piece dimensions, please see the quality norm EN 10045/1 taking into account that ASTM E-23 norm has some differences related to the impact shapes.

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Tornado
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Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

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#4

Re: Measurement Unit for Charpy V Notch Impact Test

03/10/2013 11:45 PM

One decajoule (which I think your abbreviation means) is 10 joules. I don't think it is a commonly used or standard unit.

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lyn
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#5
In reply to #4

Re: Measurement Unit for Charpy V Notch Impact Test

03/10/2013 11:51 PM

Ok. I'm wrong again.
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miklosh
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#7
In reply to #5

Re: Measurement Unit for Charpy V Notch Impact Test

03/11/2013 8:51 AM

easy mistake since both use lower case 'd':

dJ=deci-Joule (0.1*J) while

daJ=deca-Joule (10*J), 'a' making the difference

Unlike the use of lower/upper case in milli- and Mega- to differentiate
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