ASTM A247 Test to Evaluate the Microstructure of Graphite in Iron Castings

Scope:

ASTM A247 is utilized to document the microstructures of graphite in iron castings, as well as to categorize the type of graphite present. This helps to enable comparisons between reports generated by diverse laboratories. This testing procedure is relevant for all iron-carbon alloys with graphite particles and can apply to gray irons, malleable irons, and ductile irons.

Test Procedure: 

ASTM A247 involves the examination of the microstructure of graphite within iron castings and comparing it with a standard size chart. This standard utilizes reference diagrams as a basis for classification, with numbers and letters used to indicate distinct features of the graphite particles. The type, distribution, and size of the graphite sample are then evaluated and rated based on how closely they resemble similar microstructures in the chart.

Video 01: MEC291 – EXPERIMENT 5: OBSERVATION ON THE MICROSTRUCTURE OF CAST IRON

Specimen Size: 

Ideally, the sample should be a section cut from an actual casting being evaluated. When that is not possible, a test projection may be cast attached to the casting, and sawed or broken off to be used as the sample. If neither of these is possible, microscopical test coupons are cast from the metal representative of the castings poured.

Data: 

The microstructure of graphite in iron casting is reported. The values stated in SI units are to be regarded as standard.

Conclusion:

The ASTM A247 test is used to evaluate the microstructure of graphite in iron castings. It provides a quantitative method to determine the amount, distribution, and morphology of graphite in cast iron samples.