The formula to calculate Number of Grains at M X (NM) is:
\[ NM = 2^{(n-1)} \left(\frac{100}{m}\right)^2 \]
Where:
Number of grains at M X represents the average number of grains per square inch at M magnification.
ASTM grain size number is represented by a number ranging from 1 to 10.
Magnification is the process of enlarging the apparent size, not physical size, of something.
Let's assume the following values:
Using the formula:
\[ NM = 2^{(n-1)} \left(\frac{100}{m}\right)^2 \]
Evaluating:
\[ NM = 2^{(5-1)} \left(\frac{100}{0.66}\right)^2 \]
The Number of Grains is 367309.4582 Grains Per Square Centimeter.
| ASTM Grain Size Number (n) | Magnification (m) | Number of Grains (NM, Grains Per Square Centimeter) |
|---|---|---|
| 4 | 0.5 | 320,000.0000 |
| 4 | 0.6 | 222,222.2222 |
| 4 | 0.7 | 163,265.3061 |
| 4 | 0.8 | 125,000.0000 |
| 4 | 0.9 | 98,765.4321 |
| 4 | 1 | 80,000.0000 |
| 5 | 0.5 | 640,000.0000 |
| 5 | 0.6 | 444,444.4444 |
| 5 | 0.7 | 326,530.6122 |
| 5 | 0.8 | 250,000.0000 |
| 5 | 0.9 | 197,530.8642 |
| 5 | 1 | 160,000.0000 |
| 6 | 0.5 | 1,280,000.0000 |
| 6 | 0.6 | 888,888.8889 |
| 6 | 0.7 | 653,061.2245 |
| 6 | 0.8 | 500,000.0000 |
| 6 | 0.9 | 395,061.7284 |
| 6 | 1 | 320,000.0000 |