To get an accurate point count, the phase of interest must be clearly identifiable.
Because manual point counting is a sampling technique, the result is an estimate accompanied by a margin of error. The standard relies on calculating the and the 95% Confidence Interval (CI) . Calculating Relative Accuracy (%RA)
The standard provides a statistical framework to estimate how much space a specific phase or constituent occupies within a three-dimensional volume based on two-dimensional cross-sections (polished metallurgical samples). The Core Principle of Stereology
I can provide more specialized information regarding this standard. If you want, tell me: astm e562-19e1
The "E562" refers to its unique identification code, while "19" indicates it was last reapproved or revised in 2019. The suffix "e1" signifies an editorial change was made to the previous version, correcting minor errors without altering its technical content.
If the grid intersection falls directly on the boundary line between the phase of interest and the matrix.
The magnification on the light optical microscope (LOM) or scanning electron microscope (SEM) should be chosen so that the microstructural features are clearly resolved. However, it should not be so high that only a fraction of a single phase particle fills the entire grid. To get an accurate point count, the phase
Point counting tracks structural porosity, un-melted powder particles, and secondary phase precipitates induced by layer-by-layer laser processing or bound metal deposition.
The material must be sectioned, mounted, ground, and polished following standard metallographic procedures (such as ASTM E3). Chemical or electrolytic etching must be applied carefully. Over-etching or under-etching will artificially alter the perceived size of the phases, skewing the point count. Step 2: Magnification and Field Selection
Choose a magnification high enough to clearly resolve the microstructural features, but low enough that the grid points do not fall continuously within a single large feature across multiple grid lines. The structure must look "random" relative to the grid. Step 3: Grid Alignment and Point Counting Calculating Relative Accuracy (%RA) The standard provides a
The user places a digital or physical transparent grid over the viewing field. Square grids of (9 points), (16 points), or (25 points) are standard.
) of a phase in a 3D volume is equivalent to the average area fraction ( Aacap A sub a ) of that phase on a randomly chosen 2D cross-section.
ASTM E562-19e1 is a widely accepted, foundational manual test method for determining the volume fraction of microstructural phases by superimposing a grid over a micrograph. Considered an economical and relatively simple technique, it is ideal for smaller labs, though it is highly operator-dependent, slow, and can have errors exceeding 10%. For a detailed overview, visit Infinita Lab .
Pp=(∑PαN×Pt)×100cap P sub p equals open paren the fraction with numerator sum of cap P sub alpha and denominator cap N cross cap P sub t end-fraction close paren cross 100