# Material science help



## Ra#id (Oct 15, 2008)

If a austenitized bar of AISI 1060 with ASTM 2 -grain size quenched in agitated oil , how can we calculate the surface and center hardness ( assume tha bar diameter as 100mm)

I have no idea of how to do this type of quetion, Please some one help me, I could not find any study materal regarding this area.


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## mudpuppy (Oct 15, 2008)

Holy crap, is that an FE study question? I don't even recognize about half the words in the question.


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## EM_PS (Oct 16, 2008)

that is a problem that of a certainty doesn't appear in FERM - maybe Mech DS? We are talking FE, not PE right?


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## Ra#id (Oct 16, 2008)

This is EIT question, PM General. I found this in NCEES online exam


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## EM_PS (Oct 16, 2008)

Ra#id said:


> This is EIT question, PM General. I found this in NCEES online exam


Hmm, again, it doesn't appear in my FERM 6th ed. If you look in Metallurgy section of Materials Science topic, they mention that due to variety of hardening methods &amp; rates of cooling, hardening data is usually presented graphically, using a variety of curve types (non-depicted, ironically). They do discuss ASTM grain size &amp; methodology for extrapolating grain size from destructive testing, but there is no mention or practice problems of calculating specific hardness from grain size data.

Check your FE reference manual under materials science/structure of matter (pages 105-106 NCEES pdf), the Jominy Hardenability curves for six steels. I don't see a way to calculate hardness without knowing cooling rate along with the distance from quenched end value. It looks like cooling rate is a look-up table value, but you still need distance from quenched end. Finally, how you would interpret center hardness is beyond me. good luck with that


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## Supe (Oct 16, 2008)

You should have two graphs, one graphing your hardness against your quenched end distance, and one depicting your diameter, your H factor (severity of cooling rate depending on quench medium/conditions), and your distance from your quenched end.

For the center hardness, you draw a line on the second graph from the diameter until it intersects the F curve, and then draw a line straight down from there to get a distance value. You take that distance value and use it on the first graph to determine your center hardness.

There are some mathematical formulas out there for various steel classifications, which factor in distance, grain size, and various elements which comprise carbon equivalency, but I'd be surprised to see this used given its practical limitations. You can see that here:

http://books.google.com/books?id=ORil4pedz...5&amp;ct=result


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## mudpuppy (Oct 16, 2008)

Ra#id said:


> This is EIT question, PM General. I found this in NCEES online exam


Wow--I'm sure glad I took the EE DS afternoon!


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## Fe#id (Oct 23, 2008)

This is not that difficult as it look

For this have to use the graphs in page 106 ( cooling rates for bars in agitated oil) and Jominy Hardenability graph in page 105 in NCESS hand book

Bar diameter 50mm

For surface hardeness

From graph in page 106

dictance = 9mm

from curve in page 105

for 1060(#2)

Hardeness = Rc32

For center hardeness

Distance = 17mm ( from curve in page 106)

Hardeness = Rc 29


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