Steel grades
The designations refer to SS / ISO standards.
SS 14 2346 = Al SS 14 2325 = Fl
SS 14 2333 = A2 SS 14 2361 = SÅ3
SS 14 2343 = A4 SS 14 2562 = SÅ5 1)
SS 14 2347 = A4 SS 14 2570 = Så7 1)
SS 14 2348 = A4 SS 14 2324 = SÅ8 1)
SS 14 2302 = Cl SS 14 2377 = SAF2205 1)
SS 14 2303 = Cl SS 14 2378 = 254 SMO 1)
SS 14 2321 = C3 SS 14 2328 = SAF2507 1)
1) = Internal or steel manufactures name
Storage
For the stocked range of fasteners the Austenitic steels A2 – EN1.4301
– SS14.2333, A4 – EN1.4401, Bumax A4 - EN1.4436 - SS14.2343
low carbon are used.
Propertyclasses acc to SS-ISO 3506.
Bumax 88 and 109 refer to Bulten Stainless Reg No 6:3.14
Mechanical properties given in the tables below apply exclusively to stocked
sizes.
Mechanical properties of martensitic and ferritic Stainless
steel fasteners
| Group |
Grade |
Property-
class |
Bolts, screws and studs 3) |
Nuts |
Tensile-strength
Rm 1)
N/mm² min. |
Sterss at 0,2
% permanent strain
Rp0,2 1)
N/mm² min |
Elongation
A_L 2)
Min. |
Stress under
Proof load Sp
N/mm² min. 1) |
HV
min. max. |
HB
min. max. |
HRC
min max. |
| Martensitic |
C1
C3
C4 |
50
70
110 7)
80
50
70 |
500
700
1100
800
500
700 |
250
410
820
640
250
410 |
0,2 d
0,2 d
0,2 d
0,2 d
0,2 d
0,2 d |
500
700
1100
800
500
700 |
-
220
350
240
155
220 |
-
330
440
340
220-
330 |
-
209
228
147
209 |
-
314
323
220
314 |
-
20
36
21
-
20 |
-
34
45
35
-
34 |
| Ferritic |
F1 4) |
45
60 |
450
600 |
250
410 |
0,2 d
0,2 d |
450
600 |
135
180 |
220
285 |
128
171 |
209
271 |
-
- |
-
- |
Mechanical properties of Austenitic Stainless steel fasteners
| Group |
Grade |
Property-
class |
Dimension-
range 5) |
Bolts, screws and studs 3) |
Nuts 3) |
Tensile-strength
Rm 1)
N/mm² min. |
Sterss at 0,2
% permanent strain
Rp0,2 1)
N/mm² min |
Elongation
A_L 2)
Min. |
Stress under
Proof load Sp
N/mm² min. 1) |
| Austenit |
A1, A2
A3, A4
and A5
Pressure
vessel |
50
70
80
Bumax 88
Bumax 88
Bumax 88
Bumax 109 |
M 39
M 24
M 24
M36
M6 - M24
¼ - 1” UNC
M 20 |
500
700
800
800
800
800
1000 |
210
450
600
640
640
640
900 9) |
0,6 d
0,4 d
0,3 d
0,3 d 8)
0,4xd
0,4xd
0,2 d |
500
700
800
800
800
800
1000 |
1) All stress values are calculated and
reported in terms of the nominal stress area of the thread and are valid
for lengths 
2,5 xd.
2) The elongation is giv en in mm x nominal
sthread diameter (d).
3) Refers to test on finished products, not
a prepared test piece.
4) Max. diameter for Fl = 16 mm.
5) Must be by agreement between user and
manufacturer for property classes 70 and 80 above M24.
6) ISO 3506 specifies 50, 70 and 80. Bumax
88 and 109 are Bulten Stainless internal standard and not part of ISO
3506.
7) Hardened and annealed. Min annealing temperature
= 275 ºC
8) Bumax 88 >M30 = 0,2xd
9) Bumax 109
M14 = 800
Mechanical properties at low temperature:
The properties of steel are effected by temperature and the European pressure
vessel directive specifies the temperature limits for use of Bumax 88.
| Steel grade |
Min ºC |
Max ºC |
| Bumax 88 |
-200 |
400 |
For more information about Stainless steel fasteners
for pressure vessel application please see under “Fasteners for
pressure vessels according to PED 97 / 23 / EC”.
Mechanical properties at elevated
temperatures:
When the temperature is increasing the residual strength falls. The table
below gives the residual strength in % at elevated temperature.
| Steel Grade |
100 ºC |
200 ºC |
300 ºC |
400 ºC |
| A2 / A4 |
Approx. 85% |
Approx. 80% |
Approx. 75% |
Approx. 70% |
| Bumax |
Approx. 90% |
Approx. 90% |
Approx. 85% |
Approx. 80% |
The table above is for guidance only. The table gives
values for class 70 and 80. For class 50, please see actual material standard.
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