ISO 898-6 Specification

This part of ISO 898 specifies the mechanical properties of nuts with specified proof load values when tested at an ambient temperature range of + 10 °C to + 35 °C. Mechanical and physical properties will vary with respect to temperature and property class. Products conforming to the requirements of this part of ISO 898 are evaluated only at the ambient temperature range and may not retain the specified physical properties at higher and lower temperatures. At temperatures higher or lower than the ambient temperature range, a significant change in properties may occur. When fasteners are to be used above or below the ambient temperature range, it is the responsibility of the user to ensure that the mechanical and physical properties are suitable for his particular service conditions.

ISO 898-6 Chemical Composition

Property class Chemical composition limits (check analysis), %
c
max.
Mn
min.
p
max.
s
max.
5a; 6 - 0,50 - 0,060 0,150
8b 04a 0,58 0,25 0,060 0,150
10b 05b 0,58 0,30 0,048 0,058
12b - 0,58 0,45 0,048 0,058
Note:

a. Nuts of this property class may be manufactured from free-cutting steel unless otherwise agreed between the purchaser and the manufacturer. In such cases, the following maximum sulfur, phosphorus and lead contents are permissible: sulfur 0,34 %; phosphorus 0,11 %; lead 0,35 %.
b. Alloying elements may be added, if necessary, to develop the mechanical properties of the nuts.

ISO 898-6 Mechanical properties

Nominal thread d iameter
d
mm
Property class
04 O5 5
Stress under proof load, SP
N/mm2
Vickers hardness, HV Nut Stress  under proof load, SP
N/mm2
Vickers hardness, HV Nut Stress under proof load, SP
N/mm2
Vickers hardness, J·rv Nut.
min. ma.x. state style min. max. state style min. max. state style
8≤d ≤ 16 380 188 302 NQTa thin 500 272 353 QTb thin 690 175 302 NQTa 1
16≤ d ≤ 39 720 190
Nominal thread d iameter
d
mm
Property class
6 8
Stress under proof load, Sp
N/mm2
Vickers hardness, HV Nut Stress  under proof load, Sp
N/mm2
Vickers hardness, HV Nut Stress under proof load, Sp
N/mm2
Vickers hardness, l·IV Nut
min. max. state style min. max. state style min. max. state style
8 ≤ d ≤ 10 770 188 302 NQTac 1 955 250 353 QTb 1 890 195 302 NQTa 2
10 < d ≤ 16 780
16 < d ≤ 33 870 233 1030 295 - - -
33 < d ≤ 39 930 1090 -
Nominal thread d iameter
d
mm
Property class
10 12
Stress under proof load, Sp
N/mm2
Vickers hardness, HV Nut Stress  under proof load, Sp
N/mm2
Vickers hardness, HV Nut Stress under proof load, Sp
N/mm2
Vickers hardness, l·IV Nut
min. max. state style min. max. state style min. max. state style
8 ≤ d ≤ 10 1100 295 353 QTb 1 1055 250 353 QTb 2 1200 295 353 QTb 2
10 < d ≤ 16 1100
16 < d ≤ 39 - - 1080 260 - - -
- - - - -
Note:

Minimum hardness is mandatory only for heat-treated nuts and nuts too large to be proof-load tested. For all other nuts, minimum hardness is not mandatory but is provided for guidance only. For nuts which are not hardened and tempered, and which satisfy the proof-load test, minimum hardness shall not be cause for rejection.
a. NQT = Not quenched and tempered.
b. QT = Quenched and tempered.
c. Nuts with nominal thread diameters d > 16 mm may be quenched and tempered at the discretion of the manufacturer.

Thread
d x P
Nominal stress area of mandrel
As
Property class
    06       6     6                  8                         10          12
04  05 5 6 8 10 12
Proof load (As x Sp)
N
mm2     style l style 1 style l style 2 style  1 style 2 style 2
M8 x l
MlO x 1
MlO x 1,25
39,2
64,5
61,2
14 900
24 500
23 300
19 600
32 200
30 600
27 000
44 500
44 200
30 200
49 700
47 100
37 400
61 600
58 400
34 900
57 400
54 500
43 100
71 000
67 300
41 400
68 000
64 600
47 000
77 400
73 400
M12 x 1,25
Ml2 x 1,5
Ml4 x 1,5
92,1
88,1
125
35 000
33 500
47 500
46 000
44 000
62 500
63 500
60 800
86 300
71 800
68 700
97 500
88 000
84 100
119 400
82 000
78 400
111 200
102 200
97 800
138 800
97 200
92 900
131 900
110 500
105700
150 000
Ml6 x 1,5
Ml8 x 1,5
M18 X  2
167
215
204
63 500
81700
77 500
83 500
107 500
102 000
115 200
154 800
146 900
130 300
187 000
177 500
159 500
221500
210 100
148 600
-
-
185 400
-
-
176 200
232 200
220 300
200 400
-
-
M20 x 1,5
M20 X 2
M22 x 1,5
272
258
333
103400
98000
126 500
136 000
129 000
166 500
195 800
185 800
239 800
236 600
224 500
289 700
280 200
265 700
343 000
-
-
-
-
-
-
293 800
278 600
359 600
-
-
-
M22 X 2
M24 X 2
M27 X 2
318
384
496
120 800
145 900
188500
159 000
192 000
248 000
229 000
276 500
351 100
276 700
334 100
431 500
327 500
395 500
510 900
-
-
-
-
-
-
343 400
414 700
535 700
-
-
-
M30 X 2
M33 X 2
M36 X  3
621
761
865
236 000
289 200
328700
310 500
380 500
432 500
447 100
547 900
622 800
540 300
662 100
804 400
639 600
783 800
942 800
-
-
-
-
-
-
670 700
821 900
934 200
-
-
-
M39 X  3 1030 391400 515 000 741 600 957 900 1 123 000 - - 1112 000 -