ASTM A247-19 pdf free download.Standard Test Method for Evaluating the Microstructure of Graphite in Iron Castings.
1.1 This test method covers the classification of graphite in cast irons in terms of type, distribution, and size by visual comparison to reference pholomicrographs. This test method is intended to be applicable for all iron-carbon alloys containing graphite particles, and may be applied to gray irons, malleable irons, compacted graphite irons, and the ductile (nodular) irons.
1.2 The reference photomicrographs included in this test method are in no way to be construed as specifications. In an appropriate specification for a specific material where graphite microstructure is an important consideration, this test method may be used as a reference to concisely define the graphite microstructure required.
1.3 These reference photomicrographs are offered primarily to permit accurate reporting of microstructures of cast irons and to facilitate the comparison of reports by different laboratories or investigators.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
3. Summary of Test Method
3.1 The reference micrographs included in this standard form the basis for classification. Characteristic features of graphite particle shape and distribution are designated by numerals and letters. Type, distribution, and size of observed graphite are compared with the idealized microstructures in the standard charts and rated accordingly as closely as possible to the equal or similar microstructures in the charts.
4. Significance and Use
4.1 The comparison of observed graphite particles with the structures shown in the charts give only purely descriptive information on the type, distribution, and size of the graphite in the sample being evaluated. It does not indicate, except in a very broad way, the origin of the graphite or the suitability of the iron-carbon alloy for a particular service.
5. Test Specimens or Samples
5.1 The preferred sample is a section cut from an actual casting that is being evaluated at a location agreed upon between the manufacturer and purchaser. When this is impractical. a test lug or projection often can he appended to the casting and sawed or broken off to he used as the test sample. If neither of these methods is convenient, microstructural test coupons. such as those recommended by the Cast Iron Research Committee (5R) of the American Foundry Society3 shall be cast from metal representative of the castings poured.ASTM A247 pdf download.