TPT January 2012

A rticle

ASTM E112

GОSТ 5639

DIN 50601

Parameters

Parameters

Parameters

Grain No.

Grain No.

Grain No.

d– , mm

N , 1/mm 2 A

d , mm m

m , 1/mm 2 nom

d , mm m

m , 1/mm 2

-7 -6 -5 -4 -3 -2 -1

4

0.0625

2.828

0.125

2

0.25 0.50

1.414

-3 -2 -1

1

1 2 4 8

1

1 2 4 8

0.707 0.500 0.353 0.250 0.177 0.125 0.088 0.062 0.044 0.031 0.022 0.015 0.011

0.707 0.500 0.354 0.250 0.177 0.125

00

0.508 0.359 0.254

3.88 7.75

0 1 2 3 4 5 6 7 8 9

0 1 2 3 4 5 6 7 8 9

0 1 2 3 4 5 6 7 8 9

15.50

16 32 64

16 32 64

0.1796 0.1270 0.0898 0.0635 0.0449 0.0318 0.0225 0.0159 0.0112 0.0079 0.0056 0.0040 0.0028

31 62

124 248 496 992

128 256 512

0.0884 0.0625 0.0442 0.0312 0.0221 0.0156 0.0110 0.0078 0.0055 0.0039 0.0028 0.0020 0.0014 0.0010

128 256 512

1024 2048 4096 8192

1024 2048 4096 8192

1984 3968 7936

10 11 12 13 14

10 11 12 13 14

10 11 12 13 14 15 16 17

15872

0.0079 0.0056 0.0039

16384 32768 65536

16384 32768 65536 131072 262144 524288 1048576

31744.1 63488.1 126976.3

0.0027 131072

In all, 16 х) Nos.

In all, 18 Nos.

In all, 25 Nos.

х) Only whole numbers are given in the Table. The standard contains 30 numbers

Table 2 : Соmparative analysis of grain structure parameter values determined by three standards (magnification ×100)

• shape factor and index of asymmetry of the grain structure • grain number according to GOST 5639 and АSТМ Е112 The main advantage of the new method is the possibility of assessment of grain anisotropy in the examined structures using the variation coefficient of grain distribution in the product volume generally used in the assessment of grain structure unhomogeneity. All above-mentioned parameters are determined in commonly used units to ensure higher accuracy of design strength calculation of new materials as there is no need in conversion of conventional numbers into commonly used units. The new method was taken as a basis for a proposed standard. The new standard features a condition that each number is a monodisperse system of spheres (equiaxed grains). In the proposed standard, value of the grain diameter within the monodisperse system of spheres in which grain anisotropy is absent

and not the quantity of grains in a form of cubes in 1 mm 2 as in GOST 5639-88 is taken as the grain number. Then, the number of equiaxed grains in a unit of volume is determined by the following equation:

3 2

N

V = m pcs/mm 3

Тhis approach will ensure a clear-cut assessment of material grain anisotropy by the variation coefficient of grain distribution by sizes. If the obtained variation coefficient in the examined structure is 0.28 in a plane or -0.36 in a line, it will be the evidence of structure homogeneity in a volume. And the more this value differs from the above values, the higher anisotropy is in the volume of the examined structure. The new standard features: 1. The standard series is set for 3D structure objects 2. Spatial spherical model of structural components

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