ISO 945-1:2019 pdf free download.Microstructure of cast irons Part 1 Graphite classification by visual analvsis.
Introduction
Microstructure designation is a useful feature that provides a means of classifying the graphite form, distribution and size in cast irons.
Graphite classification by visual analysis is a well-established method which is well recognized within the foundry industry as a means of quickly determining the overall graphite microstructure of a cast iron casting.
4.S Visual classification of graphite
The reference Images given In Figixe,tj., 2. 3. 4 and S provide a basis for classifying graphite forms, distribution and size. The characteristic leatures of the graphite which occur are designated by letters and numbers. For this purpose. microstructures of graphite arc arranged In a series of reference images consisting of schematic microstructures of cast Irons. The form, distribution and size of the graphite observed are determined by comparison with the reference images. The classification is allocated as the same as that of the images that resemble them most closely at the same magnification.
NOTE The comparison of actual microstructures with schematc images or photomic-rographs depends on the subecIlve Impression of the melallographer.
S Sampling and sample preparation
5.1 Samples taken from a casting
When taking samples from a casting, it Is essential that attention be paid to the location, to the wall thickness, to the distance Irom the surface and to the presence of chills. The location of the sample In the casting shall be recorded in a report.
If more than one casting Is examined, the samples shall be taken from the same location in each casting for the purpose of comparability.
The location of the metallographic specimen shall be agreed between the manufacturer and the purchaser.
5.2 Sample preparation
The area of the polished surface to be examined shall be sufficient to give a true representation of the graphite structure. Attention shall be paid to the careful grinding and polishIng of the samples, so that the graphite particles appear in their original form, size and distribution. Inappropriate grinding and polishing can cause an unacceptable alteration of the microstructure. If necessary, the method of polishing may be agreed between the manufacturer and the purchaser.
The examination of the graphite under the microscope is usually carried out on the unetched polished section,
6 Procedure for graphite classification
6.1 ProcesIure for visual classification of graphite
The polished samples shall be scanned under a microscope in such a manner that a representative area is examined. To examine the graphite form and distrIbution, a * 100 magnificatIon should preferably be chosen. If necessary, the magnification may be adapted in relation with the wall thickness so that the form and distribution of graphite can be determined by using the reference images given in Figures 1 and 2 (see also Annexes A. Ii and C). Adjust the microscope magnification to match as dosely as possible the corresponding images In Figures land 2 before classifying the graphke form and its distribution, if appropriate. The graphite size is determined by reference to Figures 3, 4 and 5 and Table 1, preferably at x 100 magnification. Other magnihcations are permitted (see Table 1. Notes I and 2, as well as 7,4).
Examination under the microscope is carried out by direct observation in the microscope or by projection on the ground glass of the microscope or on a visual display screen. The area of view should preferably have approximately the same size as the reference Images (about 120 mm diameter). The measurement of the graphite particles can be facilitated by the use of suitably calibrated eye.pieces.
NOTE 2 The relerence images given In Figure 3.4, and 5 do not represent all thegraphite particle sizes present in each of the graphite particle size ranges given in T.dbiei.,
NOTE 3 The schematics thow some graphite particles smaller then the minimum Size graphite particles for each size range. The schematics represent what can be seen when viewing a two dimensional sectioned view
a three dimensional structure where a normal sized particle Is sectioned not throtagh its centreline appears smaller than Its chaal size.
8 DesignatIon of graphite by form, distribution and size
8.1 Designation system
To characterize the graphite observed, indications are generally necessary on the form, distribution and size of the graphite particles. For this purpose, the following symbols shall be used at different positions of the designation:
— the Roman numbers given in Figure I are used for the graphite form at position 1;
— for form I, the capital letters given In FIgure 2 are used for the distribution at posItion 2;
— the Arabic numbers given In Figures3 4. and Sand Tablel are used for thegraphite size at position 3. EXAMPLE 1 For a grey cast Iron with flake (lameltar) shaped graphite particles of form I, distrlbucon A. and size 4. the following designation is used to describe that structure:
1A4
EXAMPLE 2 For a cast Iron with spheroidal graphite particles of form VI and sIze 4. the following designation is used to describe that structure:
8.3 Designation of mixed graphite forms, distributions and sizes
More complex microstructures containing different types of graphite can bc defined by estimating the percentage proportions olthe different types of graphite.
EXAMPLE I For a cast Iron with a graphite area coniprlsing 60% flake (tamellar) shaped graphite particles of form I, dtstnbutlon A and size 4 and 40% [lake (ta,nellarj shaped graphite particles of form I. distribution 0 and size 7, the following designation is used to describe the structure:
60%1A4+40%ID7
EXAMPLE 2 Fora cast iron with a graphite area comprising AS % spheroidal graphite particles of farm VI and size 4 and 15% vermicular graphite particles of form III and covering sizes 3 and 4. the following designation is used to describe the Structure:
BS%V14. 15%1I13/4
8.4 DesignatIon of unclassified graphite forms
ltgraphite particles are not Identiliable to the graphite forms in this document, these should be reported as unclassified graphite forms in accordance with this document.
8.5 Nodule count
The graphite nodule count 0F is determined by using the planimetric method, as shown by Formula (1) (see ISO 643). Nodules are particles normally classified as form VI or V (or even form IV).