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Hello!

Another ASTM question for you all.  I recently gave a presentation on grain size measurement and, as usual, I was humbled by how much I did not understand before going into writing the slideshow.

One facet that I have been unable to grasp is how ASTM Grain Sizes of less than 1 are defined.  Comparison charts exist, and E112 describes, grain sizes of 0.5, 0 and 00.  However, the mathematical definition of ASTM Grain size (N_AE=2^G-1) would give non-sensical values of grain density if you plugged in 0.5 or 0 in for G.  00 is not even a proper number.

If I had to guess, I think the sizes are divisions of G = 1 (1 grain/in² at 100X) into quarters.  The grain density for G = 0.5, 0, and 00 are 0.71, 0.5, and 0.25 grains/in² at 100X respectively.  I think there is a simple division of the grain density going on, with a then somewhat arbitrary assignment of a grain number to represent it. 

Anyone know if I'm on the right track there, or maybe have some better knowledge to what the reasoning is?  The mathematical description just seems to break down at this point.

Thanks,

Stephen

Hello!

Another ASTM question for you all.  I recently gave a presentation on grain size measurement and, as usual, I was humbled by how much I did not understand before going into writing the slideshow.

One facet that I have been unable to grasp is how ASTM Grain Sizes of less than 1 are defined.  Comparison charts exist, and E112 describes, grain sizes of 0.5, 0 and 00.  However, the mathematical definition of ASTM Grain size (N_AE=2^G-1) would give non-sensical values of grain density if you plugged in 0.5 or 0 in for G.  00 is not even a proper number.

If I had to guess, I think the sizes are divisions of G = 1 (1 grain/in² at 100X) into quarters.  The grain density for G = 0.5, 0, and 00 are 0.71, 0.5, and 0.25 grains/in² at 100X respectively.  I think there is a simple division of the grain density going on, with a then somewhat arbitrary assignment of a grain number to represent it. 

Anyone know if I'm on the right track there, or maybe have some better knowledge to what the reasoning is?  The mathematical description just seems to break down at this point.

Thanks,

Stephen

Hello!

Another ASTM question for you all.  I recently gave a presentation on grain size measurement and, as usual, I was humbled by how much I did not understand before going into writing the slideshow.

One facet that I have been unable to grasp is how ASTM Grain Sizes of less than 1 are defined.  Comparison charts exist, and E112 describes, grain sizes of 0.5, 0 and 00.  However, the mathematical definition of ASTM Grain size (N_AE=2^G-1) would give non-sensical values of grain density if you plugged in 0.5 or 0 in for G.  00 is not even a proper number.

If I had to guess, I think the sizes are divisions of G = 1 (1 grain/in² at 100X) into quarters.  The grain density for G = 0.5, 0, and 00 are 0.71, 0.5, and 0.25 grains/in² at 100X respectively.  I think there is a simple division of the grain density going on, with a then somewhat arbitrary assignment of a grain number to represent it. 

Anyone know if I'm on the right track there, or maybe have some better knowledge to what the reasoning is?  The mathematical description just seems to break down at this point.

Thanks,

Stephen

Stephen:

Math aside, what actual applications involve grain sizes of the order of 1 sq. inch?  In my professional life I was dealing with grain sizes of about 8 to 12 ASTM grain size numbers.

Hello!

Another ASTM question for you all.  I recently gave a presentation on grain size measurement and, as usual, I was humbled by how much I did not understand before going into writing the slideshow.

One facet that I have been unable to grasp is how ASTM Grain Sizes of less than 1 are defined.  Comparison charts exist, and E112 describes, grain sizes of 0.5, 0 and 00.  However, the mathematical definition of ASTM Grain size (N_AE=2^G-1) would give non-sensical values of grain density if you plugged in 0.5 or 0 in for G.  00 is not even a proper number.

If I had to guess, I think the sizes are divisions of G = 1 (1 grain/in² at 100X) into quarters.  The grain density for G = 0.5, 0, and 00 are 0.71, 0.5, and 0.25 grains/in² at 100X respectively.  I think there is a simple division of the grain density going on, with a then somewhat arbitrary assignment of a grain number to represent it. 

Anyone know if I'm on the right track there, or maybe have some better knowledge to what the reasoning is?  The mathematical description just seems to break down at this point.

Thanks,

Stephen

Stephen:

Math aside, what actual applications involve grain sizes of the order of 1 sq. inch?  In my professional life I was dealing with grain sizes of about 8 to 12 ASTM grain size numbers.

Hello!

Another ASTM question for you all.  I recently gave a presentation on grain size measurement and, as usual, I was humbled by how much I did not understand before going into writing the slideshow.

One facet that I have been unable to grasp is how ASTM Grain Sizes of less than 1 are defined.  Comparison charts exist, and E112 describes, grain sizes of 0.5, 0 and 00.  However, the mathematical definition of ASTM Grain size (N_AE=2^G-1) would give non-sensical values of grain density if you plugged in 0.5 or 0 in for G.  00 is not even a proper number.

If I had to guess, I think the sizes are divisions of G = 1 (1 grain/in² at 100X) into quarters.  The grain density for G = 0.5, 0, and 00 are 0.71, 0.5, and 0.25 grains/in² at 100X respectively.  I think there is a simple division of the grain density going on, with a then somewhat arbitrary assignment of a grain number to represent it. 

Anyone know if I'm on the right track there, or maybe have some better knowledge to what the reasoning is?  The mathematical description just seems to break down at this point.

Thanks,

Stephen

Hello!

Another ASTM question for you all.  I recently gave a presentation on grain size measurement and, as usual, I was humbled by how much I did not understand before going into writing the slideshow.

One facet that I have been unable to grasp is how ASTM Grain Sizes of less than 1 are defined.  Comparison charts exist, and E112 describes, grain sizes of 0.5, 0 and 00.  However, the mathematical definition of ASTM Grain size (N_AE=2^G-1) would give non-sensical values of grain density if you plugged in 0.5 or 0 in for G.  00 is not even a proper number.

If I had to guess, I think the sizes are divisions of G = 1 (1 grain/in² at 100X) into quarters.  The grain density for G = 0.5, 0, and 00 are 0.71, 0.5, and 0.25 grains/in² at 100X respectively.  I think there is a simple division of the grain density going on, with a then somewhat arbitrary assignment of a grain number to represent it. 

Anyone know if I'm on the right track there, or maybe have some better knowledge to what the reasoning is?  The mathematical description just seems to break down at this point.

Thanks,

Stephen

Stephen and co -

There is nothing wrong with that formula or Table 4.

See below.

However, for large grains, you really should be using Table 3, for macroscopic

grain size.

More importantly, you can refer specific questions about E112 to its subcommittee.

See below.   Travis can put you in contact with the correct person, likely George VdV.

regards,

- Jim

Committee E04 Officers and Staff Support
Staff Manager: Travis Murdock (tmurdock@astm.org)

Committee Officers
Editor: Emilie Whealen
Chair: Gabriel Lucas
Member-At-Large: George F. Vander Voort
Second Vice-Chair: Janet Gbur
Administrative Assistant: Jill Dicicco
Member-At-Large: John G. Chir
Recording Secretary: Lesley D. Frame
First Vice-Chair: Margaret P. Willis
Membership Secretary: Matt Simons
Staff Manager: Travis Murdock

Hello!

Another ASTM question for you all.  I recently gave a presentation on grain size measurement and, as usual, I was humbled by how much I did not understand before going into writing the slideshow.

One facet that I have been unable to grasp is how ASTM Grain Sizes of less than 1 are defined.  Comparison charts exist, and E112 describes, grain sizes of 0.5, 0 and 00.  However, the mathematical definition of ASTM Grain size (N_AE=2^G-1) would give non-sensical values of grain density if you plugged in 0.5 or 0 in for G.  00 is not even a proper number.

If I had to guess, I think the sizes are divisions of G = 1 (1 grain/in² at 100X) into quarters.  The grain density for G = 0.5, 0, and 00 are 0.71, 0.5, and 0.25 grains/in² at 100X respectively.  I think there is a simple division of the grain density going on, with a then somewhat arbitrary assignment of a grain number to represent it. 

Anyone know if I'm on the right track there, or maybe have some better knowledge to what the reasoning is?  The mathematical description just seems to break down at this point.

Thanks,

Stephen