Heat Treatment and Metallurgy Lab

How to calculate ASTM grian size of microstructure which have a scale bar? Grain size analysis is used as a quality control tool to ensure that alloys are manufactured to specification.  Some examples of this include verification of the heat treatment and condition of the alloy.  It can also be used to assist in understanding material failures. I have to find ASTM grain size, I would like to know is it a correct way to find the exact magnification of microstructure using scale bar . We have the microstructure test specimen of various metals at the lab. I used those microstructure test specimen to calculate the grain size using the                           Formula N*=2exp(n-1)  at magnification of 100 X measured in an area of 1 sq. inch. I want to know if it is the standard method for obtaining the average grain size. Can anyone attach the American Society for Testing and Materials document ASTM E112-12? Calculation of ASTM Grain Size Number? Example :- Supposed we count 16

Step Down ( macro-streak-flaw ) test of steel bar. Scope:- This Standard specifies a step-down test method, blue fracture test method and magnetic particle inspection method to assess the non-metallic inclusions in rolled or forged steel with the naked eye or using a magnifying glass with a magnification of not more than 10x. Test piece:- The test piece shall be machined to the dimensions given below in figure table 1 The machined surface shall not be rough but shall be fairly smooth. Test Procedure Process :- Sample preparation are complete then ,sample Deep in hydro cloric acid (HCL) temperature 70~80 Degrees centigrade for 1 Hrs. After process are complete then clean with hot & cold water . Method of Examination:- The length and the number of flaws shall be determined under good illumination cither with an unaided eye or with low magnafication 15x Terminology:- A:- For the purpose of this standard the streak flaw shall mean defects arising from non-metali