ASTM E() – Standard Test Methods for Determining Average Grain Size Using Semiautomati. Purchase your copy of ASTM E – 97() as a PDF download or hard copy directly from the official BSI Shop. All BSI British Standards. The ASTM Designation: E–97 requires five hundred data points for a given sample and this analysis is time-consuming and tedious for the.
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This is easily performed, without producing bias, if enlargements are used. Some boundaries are light while others are missing.
This procedure should be repeated on each of at least? The grains of interest are detected as described in Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. Table 4 lists the values of t as a w1382 of n or N.
ASTM E1382 – 97(2015)
A very high degree of grain boundary delineation is required. For this example, we obtain 2. Consequently, the imaging system must be kept clean. Because of the uncertainties introduced by such procedures, r1382 should be used with caution, or avoided, until their in? With an inverted-type microscope, simply place the specimen face down on the stage plate and hold it in place with the stage clamps.
L P mm-1 If measurements were made on only a single plane, asm example, the longitudinal plane, report that this was done and the nature of the e13822 method, plus the statistical evaluation of the data. For such specimens, semiautomatic digitizing tablet measurements are preferred. The measurement area is the sum of the grain interior and grain boundaries between these grains, Ati.
Divide each area, Ai, by the magni? L, or the mean grain boundary intersections per unit length, P? If the histogram reveals a duplex condition, calculate s for the intercepts within each region of the distribution curve.
Automatic image analyzers are affected by these problems to a greater degree atsm are semiautomatic digitizing tablet measurements. In this case, the average number of intercepts or intersections should be at asfm 25 per circle. The cursor is moved over the tablet surface and the microscopist can see the illuminated cross hairs in the cursor through the eyepieces over the? The choice of the proper etchant depends on the composition and heat treatment condition of the specimen.
This procedure is useful for showing the overall mean shape of the grains but does not give size information.
The ratio of the average chord lengths parallel and perpendicular to the deformation direction de? Generally, each test line will begin and end within a grain and these partial chords are not measured see Table 1.
No further reproductions authorized. There may be other possible methods, or other equivalent procedures, that can be used to measure grain size.
Reference 1 provides guidance for development of prior-austenite grain boundaries. Avoid an excessively high number of grains per aatm as counting accuracy may be impaired. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters. A values for the? E1328 the entire area of the largest observed grain section. A sufficient number of? Most digitizing tables have software programs established for such computations.
Sampling location and frequency should be based upon agreements between manufacturers and users. Detection of these features, particularly during measurement with an automatic image analyzer, will bias test results. Afor n measured? The grain structure is nearly completely revealed without the twin boundaries. In most cases except for thin sheet or wire specimensa minimum polished surface area of mm2 0.
These devices relieve much of the tedium associated with manual measurements, thus permitting collection of astk larger amount of data and more extensive sampling which will produce better aztm de?
Use of a programmable stage prevents bias in? When using a live microscope image and an eyepiece reticle, simply select more? Excessive relief, pitting or pullout must be ast. Measure only whole intercept lengths, ignore intercepts that end within a grain.
Vibrations, if excessive, must be isolated, particularly for automatic image analysis.
L value is converted grain size was found to be Each grain boundary cut by the test line is also counted as one intersection. Drop the measurement grid onto the photograph to prevent placement bias. Methods based on the mean intercept length or the number of grain boundary intersections per unit length are directly related to the grain boundary surface area per unit volume, SV.
Take the micrographs at random, that is, without bias in the? If the degree of grain elongation is of interest, measure the average chord length parallel and perpendicular to the deformation direction in the same manner as described in If a programmable stage is available, set the stage controls to sample the image in a systematic manner.
For automatic image analysis, the computer also controls all of the operations except, perhaps, focusing automatic focusing is optional. The grain size measurement methods described in the following paragraphs are those known to produce results with acceptable precision and minimal bias. Then, make enlargements of the grain structure images using the same enlarger setting.