Astm E562-19e1

The primary goal of ASTM E562 is to provide a statistically valid estimate of the relative amount (volume fraction) of a specific phase within a material. For example: Duplex Stainless Steels : Measuring the ratio of ferrite to austenite. Cast Irons : Determining the percentage of graphite vs. pearlite. Alloy Development : Tracking the volume of precipitates or secondary phases. 2. The Methodology: Manual Point Counting

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Where ( 1.96 ) is the z-score for 95% confidence. The total number of grid points counted across all fields is then ( P / V_V ). In practice, the standard also provides a convenient table (Table 1) that prescribes the minimum total number of points to be counted (e.g., 400 points for a phase with ( V_V \approx 0.50 )) to achieve the desired precision, regardless of the number of fields examined. This eliminates guesswork and provides objective stopping criteria. The primary goal of ASTM E562 is to

The volume fraction wasn't 0.5%. It was 1.8%. pearlite