ASTM A247-2019 pdf free download

ASTM A247-2019 pdf free download.Standard Test Method for Evaluating the Microstructure of Graphite in Iron Castings
1. Scope
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 photomicrographs. 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 labora- tories 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. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.6 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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 ofthe 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 be appended to the casting and sawed or broken off to be used as the test sample. If neither of these methods is convenient, microstruc- tural test coupons, such as those recommended by the Cast Iron Research Committee (5R) of the American Foundry Society 3 shall be cast from metal representative of the castings poured.
7. Classification of Graphite Form Using Chart
7.1 The graphite form type chart (Fig. 1) is used as a reference standard by scanning the polished specimen under the microscope and noting the graphite forms in the micro- structure that more nearly correspond to type designations on the chart. The percentages of each graphite type are estimated by observation, or better, by counting the particles ofeach type. Types present in a sample are to be reported in percentages to total 100. Any convenient magnification that clearly reveals the graphite form may be used. 7.2 Type I graphite is nodular in shape and is the normal and usually desirable graphite form in ductile iron. 7.3 Type II graphite consists of slightly irregular nodules and has little or no adverse effect on properties of ductile iron. 7.4 Type III is the graphite form most often seen in malleable iron castings after annealing. Some malleable irons may also contain Type I or II graphite particles. 7.5 Type IV is the predominant graphite form in compacted (vermicular) graphite iron. However, the microstructure is typically evaluated by the percentage of Types I and II that are commonly observed. 7.6 Type V is the spiky graphite form occasionally seen in ductile iron in conjunction with Types I and II.