Purchase your copy of ASTM E – 02() as a PDF download or hard copy directly from the official BSI Shop. All BSI British Standards. Find the most up-to-date version of ASTM E at Engineering ASTM E – E – 02 The test methods provide for reporting of specic, distinctive informati.
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E — 02 The test methods provide for reporting of specic, distinctive information for each type of duplex grain size.
And, as an alternative, the test methods offer a procedure for statistically determining the distribution of all the grain sizes present in a duplex grain size specimen. Signicance and Use 5. For comparison of mechanical properties with metallurgical features, or for specication purposes, it may be important to be able to characterize grain size in such materials. Assigning an average grain size value to a duplex grain size specimen does not adequately characterize the appearance of that specimen, and may even misrepresent its appearance.
For example, averaging two distinctly different grain sizes may result in reporting a size that does not actually exist anywhere in the specimen. Examples of random duplex grain sizes include: Examples of topological duplex grain sizes include: If duplex grain size is suspected in a product too large to be polished and etched as a single specimen, macroetching should be considered as a rst step in evaluation.
The entire macroetched cross-section should be used as a basis for estimating area fractions occupied by distinct grain sizes, if possible. If microscopic examination is subsequently necessary, individual specimens must be taken to allow estimation of area fractions for the entire product cross-section, and to allow determination of grain sizes representing the entire crosssection as well.
Duplex grain structures for example, multiphase alloys are not necessarily duplex in grain size, and as such are not the subject of these methods.
However, the test methods described here for area fraction estimation may be of use in describing duplex grain structures. These items are briey described below, under the headings of the specic procedures to which they apply. This comparison chart is shown in Fig. The chart shows different area percentages of light grains among dark grains.
The grid should consist of equally spaced points formed by the intersection of ne lines. Practice E FIG.
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The regions occupied by a distinct grain size are manually outlined on a photomicrograph or transparent overlay. The area of each astj those regions is then measured by tracing its outline with the planimeter.
These are available from microscope manufacturers. The test grid consists of a square network of grid lines, with a recommended interline spacing of 5 mm.
MSQ ASTM Grain Size Calculation, Grain Size Measurement
Use of the grid is described in Methods E The use of these is described in detail in Methods E The test grid consists of a series of ne, parallel lines, with an interline spacing of 5 mm.
Qstm of the grid is described in 8. This procedure can be carried out much more efficiently through the use of an automated image analysis system with an electronic pencil or cursor, or through the use of a semi-automated image analysis system with a digitizing tablet and electronic pencil or cursor.
Sampling and Test Specimens 7. To characterize these patterns accurately, the entire cross-section of the specimen or product must be evaluated.
Accordingly, the longitudinal orientation is recommended, with one exception. If the specimen being examined is the full cross-section of a round bar, the longitudinal section should not be used asgm estimate the ashm fraction aztm by different grain sizes.
That estimate can be made w1181 accurately only on a transverse section. For a tubular product, estimates of area fractions made on longitudinal sections are reasonable approximations of the same estimates made on transverse sections. For all other products, area fraction estimates should be equally accurate with either specimen orientation.
For instance, banding present in a given specimen may not be easily recognizable in a transverse orientation. Etch specimens so that all grain boundaries are distinct and easily visible. An example photomicrograph of the ALA condition appears in Fig.
An example photomicrograph of the wide-range condition appears in Fig. F1181 example photomicrograph of the bimodal condition appears in Fig. A further example appears in Fig. An example photomicrograph of a cross-section condition appears in Fig. An example photomicrograph of the necklace condition appears in Fig. An example photomicrograph of the banding condition appears in Fig.
Four procedures for estimating area fraction are described, the simplest to apply resulting in the least precision, and the most complicated resulting in the greatest precision.
ASTM E1181 – 02(2015)
One, the Direct Measurement Procedure see 8. If this is not practical, apply the estimation procedure to as much of the specimen as is reasonable, but recognize that, by not sampling all of the specimen area, some undened bias may be introduced into the estimate.
The most precise astn of the area fractions occupied by each grain size will be obtained by evaluating the entire surface of that specimen. Selecting only part of the specimen surface may inadvertently eliminate areas that have high or low concentrations of one of the grain sizes, thus biasing the estimate. If neither of these is practical, then, as an absolute minimum, the area of the specimen to be examined must include one complete traverse from surface to surface of the original plate section.
If additional traverses can be made, they will improve the precision of the nal area fraction estimate.
Such a method is subject to considerable error. Reduce that error by using graded area fraction comparison gures see Fig. Compare such gures with eyepiece or projected images from a microscope, or with photomicrographs. Use the lowest magnication that allows visual resolution of the coarse- and ne-grained areas as distinct regions.
Note that it is not necessary to resolve the individual ne grains in the image. The area occupied by the ne grains is what must be determined. Apply this practice to projected images from a microscope, or to photomicrographs. Begin by outlining the distinct grain size regions in a given image, either on a transparent overlay placed over the projected image, or directly on a photomicrograph. Such outlining will simplify decisions during point counting, and thus speed the counting process.
On the overlay, also mark the outline of the total eld of view the limits of the image. Next apply a regular two-dimensional grid to the outlined image. The grid spacing should be matched to the image magnication to fulll the recommendations of Practice E Count the number of grid points falling within the particular grain size region being evaluated. If there is any doubt whether a point falls inside or outside the outlined region, count the point as one half. Estimate the area fraction for the grain size region being evaluated as the number of grid points falling within the region, divided by the total number of grid points that lie within the total image outline the grid must be large enough to completely cover the total image.
Apply this procedure to projected images from a microscope, or to photomicrographs. Begin by manually outlining all of the areas occupied by one of the distinct grain sizes in a given image, either on a transparent overlay placed over the projected image, or directly on the photomicrograph. Then use the planimeter to measure the area enclosed within each outlined region.
Also use the planimeter to measure the total area of the image. Estimate the area fraction for the grain size being evaluated as the total of the areas of the outlined regions, divided by the total image area. Make at least 10 measurements at different locations of the depth of a given surface layer, and calculate the average depth from those measurements. Use this average and the overall product dimensions to calculate an estimated area fraction for that surface layer.
Suppose that measurements indicate that the surface layers each average 3.
The layer depth of 3. Further suppose that measurements indicate an average depth of that surface layer of 1. A tube whose wall thickness is small compared to its outside diameter may be treated as equivalent to a product of rectangular cross-section, in that a surface layer of a e118 depth at 5 the outside diameter covers essentially the same area as a layer of the same depth at w1181 inside diameter.
Accordingly, the layer depth of 1. The Comparison Procedure is the simplest, but offers the least accuracy. The Measuring and Referee Procedures are more difficult to apply, but offer greater accuracy. Of these, the Comparison Procedure is the simplest, but offers the least precision. The Planimetric Procedure of E does not lend itself to determination of grain size in distinct small areas, and so should sstm be used. Any of the Intercept Procedures of E may be used, within the regions of distinct grain size.
These procedures will be more difficult to apply than the Comparison Procedure of E, but will offer greater precision. These different applications are described in 8. Use Methods E to determine the average size of the balance of the grains in the specimen.
An example of a complete report might read: Use Methods E to determine the size of the smallest grains found in the specimen, and Methods E to estimate the size of the largest grain found in the specimen. Use one astk the procedures from 8. The distribution of intercept lengths is much more efficiently determined using a semi-automated image analysis system with a digitizing tablet and electronic pencil or cursor, or using an automated image analysis system with electronic pencil or cursor.
Follow this process for each grain in turn along one grid line, and repeat the process for each grid line. F1181 the aztm are completed for one grid position, rotate the grid to another position, and repeat the entire process. These data asm be used to assess the nature of the observed grain size distribution, and to determine mean intercept lengths and area fractions for distinct segments of a total distribution.
A xstm application of this procedure appears in Appendix X1, along with formulas for calculating mean intercept lengths, and area fractions.
Presentation of the data as a histogram or a frequency plot is also shown. Any estimates of area fractions arising from this procedure are valid for an entire specimen only if they fulll the requirements of 8.
Classication of the duplex grain size see 8. Precision and Bias 9. Results will be incorporated here when available. Each photomicrograph is accompanied by the corresponding reporting format for that type of duplex grain size.