This British standard specifies minimum tensile strengths of
eight grades of flake graphite cast iron as determined on test
pieces from separately cast test samples. It does not specify
the properties of castings made in the material.
When tested in accordance with appendix A the minimum tensile
strength of the specimen shall be as given in table 1.
Table 1.
Minimum tensile strengths of test pieces machined
from separately cast test samples |
grade |
Minimum
tensile strength Rm(min) |
100
150
200
220
250
300
350
|
N/mm2
100
150
180
200
250
300
350 |
Note. The
results obtained against any particular grade may be
deemed acceptable if the specified minimum strength
is exceeded by up to 100 N/mm2 |
The dimensions of the test piece are as given
in table 2.
Table2.
Dimensions of tensile test pieces ( see figure 2) |
Dimension |
size |
Machining
tolerance |
Minimum
parallel length (Lc) |
mm 55 |
mm none |
Gauge
diameter ( d0 ) |
20 |
±0.5 |
Radius ( R ) |
25 |
+5
-0 |
Plain ends |
Minimum
diameter (d1) |
25 |
none |
Minimum
length ( Lp) |
65 |
none |
Threaded
ends |
Minimum
diameter at root of thread (d2 ) |
25 |
none |
Minimum
length (Ls) |
30 |
none |
The cooling rate of cast-on samples will be
more representative of the cooling rate of a casting than a
separately cast test sample when the casting thickness is
greater than 20mm and its mass greater than 20kg.
Table 3
Expected tensile strengths of test pieces machined
from cast- on test samples and from the castings |
Grade |
Casting
section thickness |
Tensile
strength |
over |
Up to and
including |
Cast-on test
samples |
castings |
100 |
mm
2.5
10 |
mm
10
20 |
N/mm2
-
- |
N/mm2
120
90 |
150 |
2.5
10
20
40
80
150 |
10
20
40
80
150
300 |
-
-
120
110
100
90 |
155
130
110
95
80
- |
180 |
2.5
10
20
40
80
150 |
10
20
40
80
150
300 |
-
-
150
135
125
100 |
185
160
135
115
100
- |
200 |
2.5
10
20
40
80
150 |
10
20
40
80
150
300 |
-
-
170
150
140
130 |
205
180
155
130
115
- |
220 |
2.5
10
20
40
80
150 |
10
20
40
80
150
300 |
-
-
175
165
150
140 |
220
195
170
145
130
- |
250 |
5
10
20
40
80
150 |
10
20
40
80
150
300 |
-
-
210
190
170
160 |
250
225
195
170
155
- |
300 |
10
20
40
80
150 |
20
40
80
150
300 |
-
250
220
210
190 |
270
240
210
195
- |
350 |
10
20
40
80
150 |
20
40
80
150
300 |
-
290
260
230
210 |
315
280
250
225
- |
The expected ranges of Brinell hardness for various casting section sizes are given in table 4.
Table 4
Expected brinell hardness ranges for different
casting section sizes |
Grad |
Section
thickness (in mm) |
Expected
brinell hardness ranges |
100 |
2.5-5
5-10
10-20
20-40
40-80 |
＜210
＜185
＜170
＜160
＜150 |
150 |
2.5-5
5-10
10-20
20-40
40-80 |
260 to 170
225 to 140
205 to 125
185 to 110
170 to 100 |
200 |
2.5-5
5-10
10-20
20-40
40-80 |
≤280
260 to 170
230 to 150
210 to 135
190 to 120 |
250 |
2.5-5
5-10
10-20
20-40
40-80 |
-
280 to 200
250 to 180
235 to 160
220 to 145 |
300 |
2.5-5
5-10
10-20
20-40
40-80 |
-
-
280 to 200
255 to 180
240 to 165 |
350 |
2.5-5
5-10
10-20
20-40
40-80 |
-
-
-
280 to 200
260 to 185 |
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