ASTM A247 Flake Graphite
ASTM A247 Nodular Graphite

ASTM A247 is a method of evaluating the microstructure of graphite in iron castings.

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APM Testing provides A2LA accredited services for graphite microstructure testing per ASTM A247 at a fair price, with prompt delivery, and a detailed test report. Our laboratory also provides laboratory services for plastic testing, metal testing, rubber testing, oil testing, paint testing, plating testing, adhesive testing, circuit board testing, and other testing.

Purpose: Cross section an iron casting to reveal its graphite microstructure per ASTM A247.

Sample: One section 1 x 1 x 0.25 inches (25 x 25 x 6 mm) or smaller cut from an iron casting.

Basic Description: ASTM A247 is a method of evaluating the microstructure of graphite in iron castings. The casting is cross sectioned and polished per ASTM E3 prior to examination. The excess carbon in iron castings separates into graphite of various forms. Iron castings with graphite flakes (gray iron) are not as strong or impact resistant as those with round nodular graphite (ductile iron). ASTM A247 provides images used to classify the form, distribution, and size of the graphite in an iron casting. Graphite forms range from the strongest nodular graphite (Type I) to the weaker flake graphite (Type VII). Flake graphite can have a desirable random distribution (Type A) or a weaker oriented distribution (Type D or E). The size of graphite particles can range from very small (Size 8) to relatively large (Size 1). Graphite microstructure is useful in predicting the strength and impact resistance of an iron casting at specific locations. Other microstructural details of iron castings and metals can be revealed by etching per ASTM E407. Graphite microstructure results are presented in the form of a microscopic image with a results table classifying the graphite.

Limitations: This method is only intended for the microstructure of graphite in iron castings. Other microstructural details must be evaluated using different methods. Good microstructural results require significant preparation to obtain a mirror finish with no scratches or edge rounding prior to etching. High magnification optical microscopy is required to reveal important details.


  • Reichert Polyvar, Optical Microscope with Digital Camera, 20 to 2,000X

Method Publisher:


  • Graphite Microstructure
  • Flake Graphite
  • Nodular Graphite
  • Metallographic Examination
  • Microstructural Analysis
  • Iron Castings
  • Ductile Iron
  • Gray Iron
  • Malleable Iron

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