Astm E562-19e1 -

The logic behind ASTM E562 is elegantly simple. Rather than attempting to measure the complex, irregular areas of microstructural features, an operator superimposes a digital or physical grid of test points over an image of the microstructure. The Point Counting Grid

Cut a representative section of the material using a low-deformation cooling saw.

To understand microstructural heterogeneity, calculate the standard deviation: astm e562-19e1

= The total number of intersection points on the chosen grid. Standard Deviation (

Before analyzing the material, the specimen must be carefully prepared. This includes cutting, mounting, grinding, and polishing the material’s surface to a mirror-like finish. Finally, the surface is usually using a chemical reagent (e.g., 2% nital for carbon steels or specialized etchants for stainless steels) to reveal the boundaries of the different phases. Care must be taken to prevent smearing the metal or gouging out the second phase during etching, as this directly affects point-counting accuracy. 2. Selecting the Magnification The logic behind ASTM E562 is elegantly simple

The grid spacing must be larger than the average size of the phase features being measured to prevent multiple adjacent points from falling into the same individual phase pool (which introduces statistical bias). 3. Scoring Rules

Samples are ground and polished to a mirror finish, typically down to diamond or alumina suspension. Finally, the surface is usually using a chemical reagent (e

(Area Fraction): The area of the constituent divided by the total area of the microstructure on a random cross-section. PPcap P sub cap P