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digbijaya igit
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Asked: 2020-04-15T05:56:34+05:30 In:

Is there any formulae to calculate the grain size diameter from the ASTM grain size number?

Is there any formulae to calculate the grain size diameter from the ASTM grain size number?
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    8 Answers

    1. Gold Coaching Institute for GATE Metallurgy having dedicated faculty pool from IITs & IISC.
      This answer was edited.

      Glad you asked it. At career aveues we believe in short tricks and tips for gate preparation. So, here we present shortcut to calculate 2 parameter using one equation. So, Basically there are three parameters that you can calculate using ASTM number (G). D = grain diameter at 1X magnification (mm) nRead more

      Glad you asked it.

      At career aveues we believe in short tricks and tips for gate preparation. So, here we present shortcut to calculate 2 parameter using one equation.

      So, Basically there are three parameters that you can calculate using ASTM number (G).

      1. D = grain diameter at 1X magnification (mm)
      2. na = number of grains at 1X magnification (mm-2)
      3. Na = number of grains at 100X magnification (inch-2)

      Formulae to calculate all 3 is given in the image. calculate and check with respective G value given in the table.

      Now, you can calculate D and na using formula given in the image. Just erase negative sign and 2 in the formulae of D and you will get formuale for na.

      You can interchange value of 2nd and 3rd parameter using this formulae.

      and 1 inch = 25.4 mm.

      NOTE – –

      • this formulae can be used to calculate D and then calcualte yeild strength using hall petch equation. (given value of two constants)
      • Please take care with units and magnification while calculating.

       

      YOU KNOW WHAT YOU DON’T EVEN NEED ANY FORMULAE TO CALCULATE D USING G.

      OBSERVE D VALUES CAREFULLY, YOU WILL BE AMAZED. IT’S SECRET 😉

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    2. D = 359/2^(n/2) n= ASTM grain size number D = grain size diameter in (micro meters)

      D = 359/2^(n/2)

      n= ASTM grain size number

      D = grain size diameter in (micro meters)

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    3. Silver

      N = 2^(n-1) Where n= ASTM grain size number N= No.of grains per square inch at 100X Magnification First  find out the number of grains per square inch. Then find out the area of one grain. Find out the diameter of the grain by assuming the grain to be spherical.

      N = 2^(n-1)

      Where n= ASTM grain size number

      N= No.of grains per square inch at 100X Magnification

      1. First  find out the number of grains per square inch.
      2. Then find out the area of one grain.
      3. Find out the diameter of the grain by assuming the grain to be spherical.
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    4. Silver Student

      By using follwing formula we can find out grain size using ASTM grain size number. D = 1/ √(10^4 * 2^(n-1)/645) (mm) For any magnification. This is the direct formula to find out grain size in mm for given ASTM grain size number(n). * Also i would like to some other points. In metallographic techniqRead more

      By using follwing formula we can find out grain size using ASTM grain size number.

      D = 1/ √(10^4 * 2^(n-1)/645) (mm)

      For any magnification. This is the direct formula to find out grain size in mm for given ASTM grain size number(n).

      * Also i would like to some other points. In metallographic techniques using line intersection method to find grain size. The basic of this method  is we require two or more fixed reference points or a fixed line which helps in estimate the grain size.

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    5. Silver Metallurgical Engineering student
      This answer was edited.
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    6. Platinum

      D=1/√N D= Grain Diameter N= no of grains at 1 magnification N=2^n-1 Where N= no of grains per inches square at 100 magnification n= grain size number

      D=1/√N
      D= Grain Diameter
      N= no of grains at 1 magnification
      N=2^n-1
      Where N= no of grains per inches square at 100 magnification
      n= grain size number

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    7. Iron

      n=(2^N-1) n= no of grains N= ASTM grain size number

      n=(2^N-1)

      n= no of grains

      N= ASTM grain size number

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    8. Gold Metallurgist, Standard Provider (IS, ASTM, BS, ISO etc), Laboratory Equipment Suppliers,
      This answer was edited.

      The average grain size is found by dividing the number of intersections by the actual line length. Average grain size =1/(number of intersections/actual length of the line). ASTM grain size number(n) is related with the number of grains(N) that you can count in 100X magnification by the relation, N=Read more

      • The average grain size is found by dividing the number of intersections by the actual line length.
        Average grain size =1/(number of intersections/actual length of the line).
      • ASTM grain size number(n) is related with the number of grains(N) that you can count in 100X magnification by the relation, N=2(n–1).
        So ASTM grain size number increases with decreasing grain size.
      • D= 1/ √(10^4 * N/645) (mm){D, Diameter} 
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