Question

A material has an ASTM grain size number of 7. Determine the magnification, if the number of grains per square inch observed is: i. 64 grains/in ii. 500 grains/in? iii. 20 grains/in-

Answer 1

A) M = 100X

B) M = 36X

C) M = 178.88X

Step-by-step explanation:

Given data:

ASTM grain size number 7

a) total grain per inch^2 - 64 grain/inch^2

we know that number of grain per square inch is given as

`Nm = 2^(n-1) ((100)/(M))^2`

where M is magnification, n is grain size

therefore we have

`64 = 2^(7-1)((100)/(M))^2`

solving for M we get

M = 100 X

B) total grain per inch^2 = 500 grain/inch^2

we know that number of grain per square inch is given as

`Nm = 2^(n-1) ((100)/(M))^2`

where M is magnification, n is grain size

therefore we have
`500 = 2^(7-1)((100)/(M))^2`

solving for M we get

M = 36 X

C) Total grain per inch^2 = 20 grain/inch^2

we know that number of grain per square inch is given as

`Nm = 2^(n-1) ((100)/(M))^2`

where M is magnification, n is grain size

therefore we have
`20 = 2^(7-1)((100)/(M))^2`

solving for M we get

M = 178.88 X