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J
anuary
2012
119
›
A
rticle
ASTM E112
GОSТ 5639
DIN 50601
Grain No.
Parameters
Grain
No.
Parameters
Grain No.
Parameters
d– ,
mm
N
A
,
1/mm
2
d
m
,
mm
m
nom
,
1/mm
2
d
m
,
mm
m
,
1/mm
2
-7
4
0.0625
-6
2.828
0.125
-5
2
0.25
-4
1.414
0.50
-3
1
1
-3
1
1
-2
0.707
2
-2
0.707
2
00
0.508
3.88
-1
0.500
4
-1
0.500
4
0
0.359
7.75
0
0.353
8
0
0.354
8
1
0.254
15.50
1
0.250
16
1
0.250
16
2
0.1796
31
2
0.177
32
2
0.177
32
3
0.1270
62
3
0.125
64
3
0.125
64
4
0.0898
124
4
0.088
128
4
0.0884
128
5
0.0635
248
5
0.062
256
5
0.0625
256
6
0.0449
496
6
0.044
512
6
0.0442
512
7
0.0318
992
7
0.031
1024
7
0.0312
1024
8
0.0225
1984
8
0.022
2048
8
0.0221
2048
9
0.0159
3968
9
0.015
4096
9
0.0156
4096
10
0.0112
7936
10
0.011
8192
10
0.0110
8192
11
0.0079
15872
11
0.0079
16384
11
0.0078
16384
12
0.0056
31744.1
12
0.0056
32768
12
0.0055
32768
13
0.0040
63488.1
13
0.0039
65536
13
0.0039
65536
14
0.0028
126976.3
14
0.0027 131072
14
0.0028
131072
15
0.0020
262144
16
0.0014
524288
17
0.0010
1048576
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
•
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:
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
Table 2
:
Соmparative analysis of grain structure parameter values determined by three standards (magnification ×100)
3
2