November 1999
DEUTSCHE NORM
Mechanical properties of fasteners made
of carbon steel and alloy steel
DIN
-
Part 1: Bolts, screws and studs (IS0 898-1 : 1999)
English version of DIN EN IS0 898-1
EN IS0 898-1
ICs 21.060.1 O
Supersedes DIN EN 20898-1,
April 1992 edition.
Mechanische Eigenschaften von Verbindungselementen aus Kohlenstoffstahl und legiertem Stahl - Teil 1: Schrauben (IS0 898-1 : 1999)
European Standard EN I S 0 898-1 : 1999 has the status of a DIN Standard.
A comma is used as the decimal marker.
National foreword
This standard has been published in accordance with a decision taken by CEN/TC 185 to adopt, without
alteration, International Standard IS0 898-1 as a European Standard.
The responsible German body involved in its preparation was the Normenausschuß Mechanische Verbindungselemenfe (Fasteners Standards Committee).
The DIN Standards corresponding to the International Standards referred to in clause 2 of the EN are as
follows:
IS0 Standard
IS0 273
IS0 898-2
IS0 898-5
IS0 898-7
IS0 6157-1
IS0 6157-3
DIN Standard
DIN EN 20273
DIN EN 20898-2
DIN EN IS0 898-5
DIN EN 20898-7
DIN EN 261 57-1
DIN EN 261 57-3
Amendments
DIN EN 20898-1, April 1992 edition, has been superseded by the specifications of EN IS0 898-1, which is
identical to IS0 898-1.
Previous editions
DIN 266: 1931x-03; DIN 589: 1931-07, 1934-01; DIN Kr 550: 1936-03; DIN 267: 1940-06, 1943-01,
1954-01, 1960-12; DIN 267-1 : 1937-04, DIN 267-2: 1937-04; DIN 267-3: 1967-1O; DIN 267-7: 1968-05;
DIN IS0 898-1 : 1979-04, 1989-01 DIN EN 20898-1 : 1992-04.
Continued overleaf.
EN comprises 30 pages.
No pari of this standard may be reproduced without the prior permission of
Y Deutsches Institut für Normung e. V., Berlin.
wth Verlag GmbH, D-10772 Berlin, has the exclusive right of sale for German Standards (DIN-Normen).
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Page 2
DIN EN IS0 898-1 : 1999-11
National Annex NA
Standards referred to
(and not included in Normative references and Annex ZB)
DIN EN 20273
Fasteners - Clearance holes for bolts and screws (IS0 273 : 1979)
DIN EN 20898-2
Mechanical properties of fasteners - Part 2: Nuts with coarse pitch thread and specified
proof load values (IS0 898-2 : 1992)
DIN EN 20898-7
Mechanical properties of fasteners - Part 7: Torsional test and minimum torques for bolts
and screws with nominal diameters 1 mm to 1O mm (IS0 898-7 : 1992)
DIN EN 261 57-1
Fasteners - Surface discontinuities - Part 1: Bolts, screws and studs for general requirements (IS0 6157-1 : 1988)
DIN EN 261 57-3
Fasteners - Surface discontinuities - Part 3: Bolts, screws and studs for special requirements (IS0 6157-3 : 1988)
DIN EN IS0 898-5 Mechanical properties of fasteners made of carbon steel and alloy steel -Part 5: Set screws
and similar threaded fasteners not under tensile stresses (IS0 898-5 : 1998)
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EN IS0 898-1
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 1999
ICs 21.060.1 O
Supersedes EN 20898-1 : 1991.
English version
Mechanical properties of fasteners made of
carbon steel and alloy steel
Part 1 : Bolts, screws and studs
(IS0 898-1 : 1999)
Caractéristiques mécaniques des
éléments de fixation en acier au
carbone et en acier allié - Partie 1:
Vis et goujons (IS0 898-1 : 1999)
Mechanische Eigenschaften von
Verbindungselementen aus Kohlenstoffstahl und legiertem Stahl Teil 1: Schrauben (IS0 898-1 : 1999)
This European Standard was approved by CEN on 1999-07-16.
CEN members are bound to comply with the CENKENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a
national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any
CEN member.
The European Standards exist in three official versions (English, French, German).
A version in any other language made by translation under the responsibility of a
CEN member into its own language and notified to the Central Secretariat has the
same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, the Czech
Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland,
and the United Kingdom.
CEN
European Committee for Standardization
Comité Européen de Normalisation
Europäisches Komitee für Normung
Central Secretariat: rue de Stassart 36, B-1050 Brussels
O 1999. CEN - All rights of exploitation in any form and by any means
reserved worldwide for CEN national members.
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Ref. No. EN IS0 898-1 : 1999 E
Page 2
EN IS0 898-1 : 1999
Foreword
International Standard
IS0 898-1 : 1999 Mechanical properties of fasteners made of carbon steel and alloy steel - Part 1: Bolts,
screws and studs,
which was prepared by ISO/TC 2 ‘Fasteners’ of the International Organization for Standardization, has been
adopted by Technical Committee CEN/TC 185 ‘Threaded and non-threaded mechanical fasteners and accessories’, the Secretariat of which is held by DIN, as a European Standard.
This European Standard has been prepared under a mandate given to CEN by the European Commission and
the European Free Trade Association and supports essential requirements of the relevant EU Directive.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, and conflicting national standards withdrawn, by February 2000 at the latest.
In accordance with the CENKENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard:
Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom.
Endorsement notice
The text of the International Standard IS0 898-1 : 1999 was approved by CEN as a European Standard without
any modification.
NOTE: Normative references to international publications are listed in Annex ZB (normative).
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EN IS0 898-1 : 1999
Contents
1 Scope
Page
........................................................................................................................................................................4
2 Normative references
3 Designation system
..............................................................................................................................................5
.................................................................................................................................................5
4 Materials ................................................................................................................................................................... 6
5 Mechanical and physical properties ...................................................................................................................... 6
6 Mechanical and physical properties t o be determined ......................................................................................
10
7 Minimum ultimate tensile loads and proof loads ............................................................................................... 12
.......................................................................................................................................................... 15
8.1 Tensile test for machined test pieces ............................................................................................................... 15
8 Test methods
8.2 Tensile test for full-size bolts, screws and studs ............................................................................................16
8.3 Torsional test
......................................................................................................................................................17
8.4 Hardness test ...................................................................................................................................................... 17
8.5 Proof load test for full-size bolts and screws ..................................................................................................17
8.6 Test for tensile strength under wedge loading of full-size bolts and screws (not studs) ........................... 19
8.7 Impact test for machined test pieces................................................................................................................ 20
8.8 Head soundness test for full-size bolts and screws with d s 1O mm and with lengths too short t o permit
wedge load testing ................................................................................................................................................... 20
8.9 Decarburization test: evaluation of surface carbon condition ....................................................................... 21
8.10 Retempering test ............................................................................................................................................... 24
8.11 Surface discontinuity inspection .................................................................................................................... 24
9 Marking ...................................................................................................................................................................24
9.1 Manufacturer's identification marking ..............................................................................................................
24
9.2 Marking symbols for property class .................................................................................................................
9.3 Identification
24
......................................................................................................................................................
25
9.4 Marking of bolts and screws with left-hand thread ........................................................................................ 27
9.5 Alternative marking ........................................................................................................................................... 28
9.6 Marking of packages .........................................................................................................................................
Annex A (informative)
temperature
28
Lower yield stress or stress at O, 2 % non-proportional elongation at elevated
.............................................................................................................................................................. 29
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EN IS0 898-1 : 1999
1 Scope
This part of I S 0 898 specifies the mechanical properties of bolts, screws and studs made of carbon steel and alloy
steel when tested at an ambient temperature range of 1 O "C to 35 OC.
Products conforming to the requirements of this part of IS0 898 are evaluated only in the ambient temperature range
and may not retain the specified mechanical and physical properties at higher and lower temperatures. Attention is
drawn to annex A which provides examples of lower yield stress and stress at 0,2 % non-proportional elongation at
elevated temperatures.
At temperatures lower than the ambient temperature range, a significant change in the properties, particularly impact
strength, 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.
Certain fasteners may not fulfill the tensile or torsional requirements of this part of IS0 898 because of the geometry of
the head which reduces the shear area in the head as compared to the stress area in the thread such as countersunk,
raised countersunk and cheese heads (see clause 6).
This part of IS0 898 applies to bolts, screws and studs
- with coarse pitch thread M1,6 to M39, and fine pitch thread M8
x 1 to M39 x 3;
- with triangular IS0 thread in accordance with IS0 68-1;
- with diametedpitch combinations in accordance with I S 0 261 and I S 0 262;
- with thread tolerance in accordance with
IS0 965-1 and IS0 965-2;
- made of carbon steel or alloy steel.
It does not apply to set screws and similar threaded fasteners not under tensile stresses (see IS0 898-5).
It does not specify requirements for such properties as
- weldability;
- corrosion-resistance;
- ability to withstand temperatures above
+ 300 "C (+ 250 "C for 10.9)or below - 50 OC;
- resistance to shear stress;
- fatigue resistance.
The designation system of this part of IS0 898 may be used for sizes outside the limits laid down in this clause (e.g.
NOTE
d > 39 mm), provided that all mechanical requirementsof the property classes are met.
Page 5
EN IS0 898-1 : 1999
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part of I S 0
898. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to
agreements based on this part of I S 0 898 are encouraged to investigate the possibility of applying the most recent
editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International
Standards.
IS0 68-1 :I 998, I S 0 general purpose screw threads - Basic profile - Part 1: Metric screw threads.
IS0 83:1976, Steel - Charpy impact test (U-notch).
IS0 261 :I 998, IS0 general purpose metric screw threads - General plan.
IS0 262:1998, IS0 general purpose metric screw threads - Selected sizes for screws, bolts and nuts.
IS0 273:1979, Fasteners - Clearance holes for bolts and screws.
IS0 724:1978, IS0 general purpose metric screw threads - Basic dimensions.
IS0 898-2:1992, Mechanical properties of fasteners made of carbon steel and alloy steel - Part 2: Nuts with
specified proof load values - Coarse thread.
IS0 898-5:1998, Mechanical properties of fasteners made of carbon steel and alloy steel - Part 5: Set screws and
similar threaded fasteners not under tensile stresses.
IS0 898-7: 1992, Mechanical properties of fasteners made of carbon steel and alloy steel - Part 7: Torsional test
and minimum torques for bolts and screws with nominal diameters 1 mm to 10 mm.
IS0 965-1:I 998, IS0 general purpose metric screw threads - Tolerances - Part 1: Principles and basic data.
IS0 965-2:1998, IS0 general purpose metric screw threads - Tolerances - Part2: Limits of sizes for general
purpose external and internal screw threads - Medium quality.
IS0 6157-13988, Fasteners - Surface discontinuities - Part 1: Bolts, screws and studs for general requirements.
IS0 6157-3:1988, Fasteners - Surface discontinuities - Part 3: Bolts, screws and studs for special requirements.
IS0 6506:1981. Metallic materials - Hardness test - Brinell test.
IS0 6507-1:1997, Metallic material - Hardness test - Vickers test - Part 1: Test method.
IS0 6508:1986, Metallic materials - Hardness test - Rockwell test (scales A - B - C - D - E - F - G - H - K).
IS0 6892: 1998, Metallic materials - Tensile testing at ambient temperature.
3 Designation system
The designation system for property classes of bolts, screws and studs is shown in table 1. The abscissae show the
nominal tensile strength values, R,, in newtons per square millimetre, while the ordinates show those of the minimum
elongation after fracture, Amin, as a percentage.
The property class symbol consists of two figures:
- the first figure indicates 1/100 of the nominal tensile strength in newtons per square millimetre (see 5.1 in
table 3);
- the second figure indicates 10 times the ratio between lower yield stress KeL (or stress at 0,2 % nonproportional elongation RpO,*) and nominal tensile strength R,, nom (yield stress ratio).
Page 6
EN IS0 898-1 : 1999
The multiplication of these two figures will give 1/10 of the yield stress in newtons per square millimetre.
The minimum lower yield stress ReL, min, (or minimum stress at 0,2 O h non-proportional elongation Rp0,2,min,) and
minimum tensile strength R,.,,, min are equal to or greater than the nominal values (see table 3).
4 Materials
Table 2 specifies steels and tempering temperatures for the different property classes of bolts, screws and studs.
The chemical composition shall be assessed in accordance with the relevant I S 0 standards.
5 Mechanical and physical properties
When tested by the methods described in clause 8, the bolts, screws and studs shall, at ambient temperature, have the
mechanical and physical properties set out in table 3.
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EN IS0 898-1 : 1999
Table 1 - System of coordinates
I
Relationship between yield stress and tensile strength
Second figure of symbol
Lower yield stress R ~ L ~
x100%
Nominal tensile strength Rm,nom
or
b
Stress at 0,2 % non-proportional elongation Rp0,2
x 100 %
Nominal tensile strength Rm,nom
t
NOTE Although a great number of property classes are specified in this part of IS0 898, this does not mean that all
classes are appropriate for all items. Further guidance for application of the specific property classes is given in the
relevant product standards. For non-standard items, it is advisable to follow as closely as possible the choice already
made for similar standard items.
a Applies only to thread diameter d s 16 mm.
Nominal values according to table 3 apply.
Page 8
EN IS0 898-1 : 1999
Property
class
Material and treatment
E
Carbon steel
+I
I
4.6
Chemical composition limits
(check analysis) % ( d m )
P
C
min.
0,20
0,05
0,06 0,003
-
0,55
0,05
0,06 0,003
-
6.8
I
8.8c
I
9.8
Carbon steel with additives (e.g. B, Mn or Cr)
quenched and tempered
Carbon steel quenched and tempered
10.9e
Carbon steel with additives (e.g. B, Mn or Cr)
quenched and tempered
f
10.9 f
0,55
Carbon steel quenched and tempered
I
0,003
0,25
"C
min.
0,05 0,06
0,05 0,06 0,003
Carbon steel with additives (e.g. B, Mn or Cr)
quenched and temgered
Carbon steel quenched and tempered
Ba
-
0,13 0,55
5.8
S
rnax. max. rnax. rnax.
Tempering
temperature
0,55 0,035 0,035
425
-r
0,15 d 0,35 0,035 0,035 0,003
0,25
0,55 0,035 0,035
0,15 d 0,35 0,035 0,035 0,003
0,25
0,55 0,035 0,035 0,003
Carbon steel with additives (e.g. B, Mn or Cr)
quenched and tempered
12.9' h i
I
I
Alloy steel quenched and tempered
I0,20
Alloy steel quenched and tempered
I0,28
1 0,55 10,03510,035
I 0,50 10,035 10,035 0,0031
380
a Boron content can reach 0,005 Yoprovided that non-effective boron is controlled by addition of titanium andor aluminium.
Free cutting steel is allowed for these property classes with the following maximum sulfur, phosphorus and leac
contents: sulfur 0,34Yo;phosphorus 0 , l l %; lead 0,35 Yo.
For nominal diameters above 20 mm the steels specified for property classe 10.9 may be necessary in order to achieve
sufficient hardenability.
In case of plain carbon boron steel with a carbon content below 0,25 YO (ladle analysis), the minimum manganese
content shall be 0,6 Yofor property class 8.8 and 0,7 % for 9.8, 10.9 and 10.9.
e Products shall be additionally identified by underlining the symbol of the property class (see clause 9).All properties of 1O.C
as specified in table 3 shall be met by 10.9,however, its lower tempering temperature gives it different stress relaxatior
characteristics at elevated temperatures (see annex A).
For the materials of these property classes, it is intended that there should be a sufficient hardenability to ensure a structure
consistingof approximately 90 % martensite in the core of the threaded sections for the fasteners in the "as-hardened''conditior
before tempering.
This alloy steel shall contain at least one of the following elements in the minimum quantity given: chromium 0,30%, nicke
0,30%, molybdenum 0,20%, vanadium 0,lO YO.Where elements are specified in combinations of two, three or four and have
alloy contents less than those given above, the limit value to be applied for class determination is 70 % of the sum of the
individuallimit values shown above for the two, three or four elements concerned.
A metallographically detectable white phosphorous enriched layer is not permitted for property class 12.9 on surfaces
subjected to tensile stress.
i The chemical composition and tempering temperature are under investigation.
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EN IS0 898-1 : 1999
Table 3 - Mechanical and physical properties of bolts, screws and studs
Sub-clause
Mechanicaland physical P i O p e I i Y
I
3.6
4.6
I
4.8
I
5.6
1
Property class
I
5.8
6.8
I
number
1
8.Ea
d s 16'
9.ab
I
10.9
I
12.9
d>16'
mm
mm
5.1
5.2
53
5.4
55
Rockwell hardness HR
5.6
5.7
5.8
5.9
5.10
Breaking torque, MB
180
~/~,,,2
Percent elongation afier lracture A
min
5.12
Reduction area after fracture. 2
%min.
5 13
Slrength under wedge loading
5.14
Impact strength, KU
5 16
5.18
0.91
0.93
310
280
0.90
O92
380
0.91
0.91
440
580
600
-
12
12
-
22
25
I
-
20
0.88
0.90
830
650
0.88
970
See I S 0 898-7
-
I
-
10
I
52
48
9
I
48
8
I
44
The values for full size bolts and screws (no studs) shall not be smaller than the minimum values for tensile strength
shown in 5.2
-
J min.
25
-
30
Head soundness
25
30
20
15
No fracture
Minimum height of non-decarburized
thread zone, E
Maximum depth of complete
decarburization c;
5.17
0,94
225
Nm min
5.1 1
5.15
O94
SdRe,or S¿Rpo2
Stress under proof load, Sp
-
mm
Hardness after retempering
Surface integrity
I
I
1
2
2
3
- ff,
3
"1
4"
0,015
I
-
Reduction oí hardness 20 HV maximum
In accordance with I C 0 6157-i or IS0 6157-3 as appropriate
a
For bolts of property class 8.8 in diameters d 6 16 mm, Ihere is an increased risk of nui stnpping in the case of inadvertent over-tightening inducing a load in excess of proof
load. Reference to is0 898-2 is recommended.
Applies only to nominal thread diameters d s 16 mm.
For structural boltingthe limit is 12 mm.
Minimum tensile properliesapply to products of nominal length i
tested (e.g. due to head configuration).
e
P
2.5 d. Minimum hardness applies to products of length I
When testing full-sizebolts. screws and studs. the tensile loads, which are to be applied for the calculation of ,R,
< 2.5 d and other products which cannot be tensile-
shall meet the values given in tables 6 and 8.
A hardness reading taken at the end of bolis. screws and studs shall be 250 HV. 238 HE or 99,5 HRB maximum.
Surface hardness shall not be more than 30 Vickers points above the measuredcore hardnesson the product when readings of both surface and core are camed oui at HV 0.3.
For property dass 10.9, any increase in hardnessat the surface which indicates that the surface hardness exceeds 390 HV is not acceptable.
In cases where the lower yield sties ReL cannot be detennined. it is permissible to measure the stress at 0,2 % non-proporlional elongation RpOp . For the property classes
4.8. 5.8 and 6.8 the values for Rd are given for calculation purposes only, they are not test values.
'
The yield stress ratio according to the designation of the property class and the minimum stress at 0,2 % non-proporlional elongation Rw,Z appiy to machinedtest specimens.
These values if received from tests of full size bolts and screws will vaw because of Drocessino method and size effects.
Page 10
EN IS0 898-1 : 1999
6 Mechanical and physical properties to be determined
Two test programmes, A and B, for mechanical and physical properties of bolts, screws and studs, using the
methods described in clause 8, are set out in table 5. Regardless of the choice of test programme, all requirements
of table 3 shall be met.
The application of programme B is always desirable, but is mandatory for products with ultimate tensile loads less
than 500 kN if the application of programme A is not explicitly agreed.
Programme A is suitable for machined test pieces and for bolts with a shank area less than the stress area.
Size
Test decisive
for acceptance
Bolts and screws with thread diameter
ds3mm
Bolts and screws with thread diameter
d>3mrn
or length 1 < 2,5 da
and length 13 2,5 d
O
O
Page 11
EN IS0 898-1 : 1999
Table 5 - Test programmes A and B for acceptance purposes
(These procedures apply to mechanical but not Che iical properties)
I
I
Property
Test programme A
I
Test method
3.6, 4.6
5.6
5.2
Minimum tensile strength,
5.3
and
5.4
and
5.5
'm,
8.1
Tensile test
8.4
Hardness test
1
Property class
Test method
8.8, 9.8
3.6, 4.6
8.8, 9.8
10.9
4.8, 5.6
10.9
5.8, 6.8
12.9
O
O
O
O
12.9
8.2
Tensile test a
-
min.
Minimum hardness
8.4
Hardness test
Maximum hardness
5.6
O
Maximum surface hardness
5.7
Minimum lower yield stress
ReL,.min.
Stress under proof load, Sp
5.10
-
Breaking torque, Me
5.1 1
Minimum percent elongation
-
Tensile test
8.1
Tensile test
-
Stress at 0,2 Yo nonproportional elongation,
III
8.1
d
5.9
IV
I
after fracture Zmin
5.14
-
loading
5.17
5.18
I II
Minimum impact strength, KI/( 8.7
Head soundness i
Maximum decarburized
zone
Hardness aiter
retempering
Surface integrity
'
8.3
Tensile test
-
Strength under wedge
5.16
__
I
Tensile test
V
8.5
after fracture, Amin
5.13
5.15
-
I I
5.12
-
O
-
5.8
Property class
II II
I I
8.6
-
load test
I o l o
Torsional test e
Wedge loading
test a
Impact test
_.
8.8
-
8.9
Decarburization
test
8.10
Retempering test'
I I
Surface discontinuity
inspection
8.1 1
*
Proof
$
8.9
Head soundness
test
Decarburization
8.10
Retempering test
-
O
O
If the wedge loading test is satisfactory,the axial tensile lest is not required
8.1 1
-
inspection
O
O
Minimum hardness applies only to products of nominal length i < 2,5 d and other products which cannot be tensile tested or torsional tested (e.g. due lo head
:onfiguration).
'
Hardness may be Vickers. Brinell or Rockwell. In case of doubt, the Vickers hardness test is decisive for acceptance.
i
Only for bolls or screws with length /
P
12
?
Only if bolts or screws cannot be tensile tested.
3
Only for bolts, screws and studs with thread diameters d 216 mm and only if required by lhe purchaser.
'
Only properíy class 5.6.
Special head bolts and screws with configurationswhich are weaker than the threaded section are excluded from wedge tensile testing requirements.
Only tor bolts and screws with thread diameters d s 1 0 mm and lengths too short lo pemit wedge load testing
Test not mandatory,to be applied as a referee test in the case of dispute only.
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EN IS0 898-1 : 1999
7 Minimum ultimate tensile loads and proof loads
See tables 6, 7 , 8 and 9.
Table 6 - Minimum ultimate tensile loads - I S 0 metric coarse pitch thread
rhread a
I
Nominal
Property class
area
3.6
4.6
4.8
5.6
5.8
6.8
8.8
9.8
12.9
M3
5,03
2 510
2 620
3 020
4020
4530
5 230
6 140
M3,5
6,78
3 390
3 530
4 070
5420
6100
7 050
8 270
M4
8,78
4 390
4 570
5 270
7020
7900
9 130
10 700
1 1 350
12 800
14 800
17 300
M5
14,2
7 100
7 380
8 520
M6
20,l
10 O00
10 400
12 100
16100
18100
20 900
24 500
M7
28,9
14 400
15 O00
17 300
23 100
26000
30 100
35 300
M8
36,6
12 100
14600
15400
18 300
19 O00
22 O00
29200
32900
38 100
44 600
M1O
58
19 100 23200
24400
29 O00
30 200
34 800
46400
52200
60 300
70 800
M12
84,3
27 800 33 700
35400
42 200
43 800
50 600
674OOc
75900
87 700
103 O00
M14
115
38 O00
46000
48300
57 500
59 800
69 O00
92 OOOc 104 O00
120 O00
140 O00
M16
157
51 800 62800
65900
78 500
81 600
94 O00 125 OOOc 141 O00
163 O00
192 O00
M18
192
63 400 76800
80600
96 O00
99 800 115 O00
159000
-
200 O00
234 O00
M20
245
80 800 98000 103000 122 O00 127 O00 147 O00 203000
-
255 O00
299 O00
M22
303
100 O00 121000 127000 152 O00 158 O00 182 O00
31 5 O00
370 O00
M24
353
116000 141 O00 148000 176 O00 184 O00 21 2 O00 293000
367 O00
431 O00
477 O00
560 O00
152 O00
230 O00 239 O00 275 O00
381 O00
-
185 O00
280 O00 292 O00 337 O00 466000
-
583 O00
684 O00
229 O00
347 O00 361 O00 41 6 O00
576000
-
722 O00
847 O00
M36
408 O00 425 O00 490 O00 678000
-
850 O00
997 O00
M39
488 O00 508 O00 586 O00 810000
252000
~
a
10.9
-
-
1 020 O00 1 200 O00
Where no thread pitch is indicated in a thread designation, coarse pitch is specified. This is given in IS0 261 and IS0 262.
To calculate A , see 8.2.
For structural bolting 70 O00 N, 95 500 N and 130 O00 N, respectively.
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Page 13
EN IS0 898-1 : 1999
Table 7 - Proof loads - IS0 metric coarse pitch thread
rhread i
(6)
Nominal
stress
area
Property class
As, nom
mm2
3.6
M3
M3,5
M4
M5
M6
M7
MB
M1O
M12
M14
M16
M l8
M20
M22
M24
M27
M30
M33
M36
M39
91o
4.6
4.8
5.6
5.8
6.8
8.8
9.8
1 130
1530
1980
1560
2 100
2720
1410
1 900
2 460
1910
2210
2980
3860
2920
3940
5100
3270
4410
5710
10.9
12.9
4180
5630
7290
4880
6 580
8 520
13100
18800
16700
24000
13800
19 500
28 O00
23800
37 700
54800
30400
48 100
70000
35 500
56 300
81 800
115
1 57
192
20 700 25900 35600 32 200 43700 50600 6670OC 74800
28 300 35300 48700 44O00 59700 69 100 91 OOOc 102000
34600 43200 59500 53 800 73000 84500 115000
95500
130000
159O00
112000
152O00
186O00
245
303
353
44 100
54 500
63 500
68600 93100 108000 147000
84800 115000 133000 182000
98800 134000 155000 212000
203 O00
252 O00
293 O00
238 O00
294O00
342 O00
459
561
694
82600
101 O00
I25O00
128O00 174000 202000 275000
157O00 213000 247000 337000
194O00 264000 305000 416000
381 O00
466 O00
576 O00
445 O00
544 O00
673 O00
817
976
147O00
176 O00
229 O00 310000 359000 490000
273 O00 371 O00 429 O00 586 O00
678O00
792O00
947O00
5.03
6,78
8,78
14,2
20,l
28,9
1 220
1580
2 560
3 620
5 200
36,6
58
84,3
6590
10 400
15200
2580
3340
3 980
5 630
8 O90
10200
16 200
23 600
t
81O O00
a
Where no thread pitch is indicated in a thread designation, coarse pitch is specified. This is given in I S 0 261 and IS0 262.
b
TO calculate A, see 8.2.
For structural bolting 50 700 N, 68 800 N and 94 500 N, respectively.
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Page 14
EN IS0 898-1 : 1999
Thread
(dxPa)
Nominal
stress
area
Property class
4,nom b
mm2
3.6
4.6
4.8
5.6
5.8
6.8
8.8
9.8
M8X1
39,2
12900
Minimum ultimate tensile load (,
N
- 16500
19600 20400 23 500 31 360 35300 I
, nom X
10.9
12.9
40800
47 800
, min)'
15 700
I
MlOXl
64,5
21 300
25 800
27 100
32300
33500
38 700
51 600
78 700
M10X1,25
61,2
20200
24 500
25700
30600
31 800
36 700
49 O00
74 700
M12 X 1,25
92,l
30400
36 800
38700
46 100
47900
55 300
73 700
112 400
M12X1,5
88,l
29100
35 200
37000
44 100
45800
52 900
70 500
107 500
152 O00
M14X1,5
125
41 200
50 O00
52500
62500
65000
75 O00 I O0 O00
M16X1,5
167
55100
66 800
70 100
83500
86800
O0 O00
90700 108000 112000
30 O00 I79 O00
63 O00 !26 O00
M18Xl,5
M20X1,5
216
71 300
86 400
272
89 800
o9 O00 I14 O00 136 O00 141 O00
204 O00
I34 O00
225 O00
264 O00
283 O00
332 O00
33 O00 I40 O00 166 O00 173 O00 !O0 O00 !76 O00
54 O00 161 O00 192 O00 200 O00 !30 O00 $19 O00
-
346 O00
406 O00
-
399 O00
469 O00
98 O00 !O8 O00 248 O00 258 O00 !98 O00 I12 O00
-
516 O00
605 O00
~~
M22X1,5
333
110000
M24X2
384
127000
M27X2
496
164000
M30X2
621
205000 !48 O00
173 O00 il5 O00
646 O00
758 O00
M33X 2
761
251 O00 104 O00
157 O00 532 O00
791 O00
928 O00
M36X3
865
285000 146 O00
i19 O00 '1 8 O00
900 O00 1 055 O00
M39x3
1030
1340000 I12 O00
i18 O00 355 O00
1 070000 1 260000
a Pis the pitch of the thread.
To calculate A, see 8.2.
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Page 15
EN IS0 898-1 : 1999
Table 9 - Proof loads - IS0 metric fine pitch thread
1
Thread
Nominal
stress
I
Property class
3.6
M8X1
39,2
MlOxl
64,5
61,2
M10X1,25
M12X1,25
4.8
5.6
5.8
6.8
8 820
12200
20 O00
19000
14 900
24 500
1 1 O00
14 500
13800
1 1 O00
18 100
17 100
23 300
17200
28400
26900
16600
20700
28600
25 800
35 O00
27300
24 700
33 500
59 900
57 300
35 O00
47 500
81 200
46 800 63 500
67000 60 500 82 100
84300 76 200 103 O00
109 O00
74900 103000 93 200 126 O00 146000 200000
86400 119000 108 O00 146 O00 169 O00 230 O00
89300 112000 154000 139 O00 188 O00 2 18 O00 298 O00
7060
1 1 600
92,l
88,l
M12X1,5
4.6
15900
19800
M14X1,5
125
22500
28100
38800
M16X1,5
167
216
272
30100
38900
37600
51 800
48600
49000 61 200
333
384
59900
69 100
M18X1,5
M20X1,5
M22X1,5
1
M24X2
M27X2
M36X3
496
M39X3
a
8.8
9.8
10.9
12.9
32500
53500
50800
38000
62700
59400
-
276 O00
323 O00
-
319 O00
412 O00
372 O00
481 O00
22 700 25500
37400 41 900
35500 39800
-
-
112 O00 140 O00 192 O00 174 O00 236 O00
1137 O00 ilil O00 1 6 O00 213 O00 289 O00
156 O00 195 O00 268 O00 242 O00 329 O00
515 O00
602 O00
632 O00
71 8 O00
738 O00
839 O00
185 O00 232 O00 31 9 O00 288 O00 391 O00
855 O00
999 O00
P is th e pitch of the thread.
To calculate A, see 8.2.
8 Test methods
8.1 Tensile test for machined test pieces
The following properties shall be checked on machined test pieces by tensile tests in accordance with I S 0 6892.
a)
tensile strength, R,;
b)
lower yield stress, ReL or stress at 0,2 % non-proportionalelongation, Rp0,2;
c)
percentage elongation after fracture:
d)
percentage reduction of area after fracture:
z=
~
sO-su
so
x 100%
Page 16
EN IS0 898-1 : 1999
The machined test piece shown in figure I shall be used for the tensile test. If it is not possible to determine the
elongation after fracture due to the length of the bolt, the reduction of area after fracture shall be measured
providing that Lo is at least 3 do.
When machining the test piece, the reduction of the shank diameter of the heat-treated bolts and screws with
d > 16 mrn shall not exceed 25 % of the original diameter (about 44 % of the initial cross-sectional area) of the test
piece.
Products in property classes 4.8, 5.8 and 6.8 (cold work-hardened products) shall be tensile tested full-size
(see 8.2).
IC
-I
I
Key
b = threaded length (b a d)
L, = length of straight portion (Lo + do)
L, = total length of test piece (L, + 2r + b)
Lu= final gauge length (see IS0 6892:1998)
Lo = 5 do or (5,65&
So = cross-sectionalarea before tensile test
d = nominal diameter
do = diameter of test piece (do < minor diameter of thread)
): original gauge length
for determination of elongation
S, = cross-sectionalarea after fracture
Lo 3 3 do: original gauge length
r = fillet radius ( r 3 4 mm)
for determination of reduction of area
Figure 1 - Machined test piece for tensile testing
8.2 Tensile test for full-size bolts, screws and studs
The tensile test shall be carried out on full-size bolts in conformity with the tensile test on machined test pieces
(see 8.1). It is carried out for the purpose of determining the tensile strength. The calculation of the tensile strength,
R,, is based on the nominal stress area As, nom:
(v)
2
As,nom =
4
where
d2
is the basic pitch diameter of the thread (see IS0 724);
d3
is the minor diameter of the thread
H
d3=dl- 6
in which
d,
is the basic minor diameter (see I S 0 724);
H
is the height of the fundamental triangle of the thread (see IS0 68-1).
For testing of full-size bolts, screws and studs the loads given in tables 6 to 9 shall be applied.
Page 17
EN IS0 898-1 : 1999
When carrying out the test, a minimum free threaded length equal to one diameter ( I d ) shall be subjected to the
tensile load. In order to meet the requirements of this test, the fracture shall occur in the shank or the free threaded
length of the bolt and not at the junction of the head and the shank.
The speed of testing, as deternined with a free-running crosshead, shall not exceed 25 mm/min. The grips of the
testing machine should be self-aligning to avoid side thrust on the test piece.
8.3 Torsional test
For the torsional test see IS0 898-7.
The test applies to bolts and screws with nominal thread diameters d 6 3 mm as well as to short bolts and screws
with nominal thread diameters 3 mm s d 6 10 mm which cannot be subjected to a tensile test.
8.4 Hardness test
For routine inspection, hardness of bolts, screws and studs may be determined on the head, end or shank after
removal of any plating or other coating and after suitable preparation of the test piece.
For all property classes, if the maximum hardness is exceeded, a retest shall be conducted at the mid-radius
position, one diameter back from the end, at which position the maximum hardness specified shall not be exceeded.
In case of doubt, the Vickers hardness test is decisive for acceptance.
Hardness readings for the surface hardness shall be taken on the ends or hexagon flats, which shall be prepared by
minimal grinding or polishing to ensure reproducible readings and maintain the original properties of the surface
layer of the material. The Vickers test HV 0,3 shall be the referee test for surface hardness testing.
Surface hardness readings taken at HV 0,3 shall be compared with a similar core hardness reading at HV 0,3 in
order to make a realistic comparison and determine the relative increase which is permissible up to 30 Vickers
points. An increase of more than 30 Vickers points indicates carburization.
For property classes 8.8 to 12.9 the difference between core hardness and surface hardness is decisive for
judgeing of the carburization condition in the surface layer of the bolts, screws or studs.
There may not be a direct relationship between hardness and theoretical tensile strength. Maximum hardness
values have been selected for reasons other than theoretical maximum strength consideration (e.g. to avoid
embrittlement).
Careful differentiation should be made between an increase in hardness caused by carburization and that due to
heat-treatmentor cold working of the surface.
NOTE
8.4.1 Vickers hardness test
The Vickers hardness test shall be carried out in accordance with IS0 6507-1
8.4.2 Brinell hardness test
The Brinell hardness test shall be carried out in accordance with I S 0 6506.
8.4.3 Rockwell hardness test
The Rockwell hardness test shall be carried out in accordance with IS0 6508.
8.5 Proof load test for full-size bolts and screws
The proof toad test consists of two main operations, as follows:
a)
application of a specified tensile proof load (see figure 2);
b)
measurement of permanent extension, if any, caused by the proof load.
Page 18
EN IS0 898-1 : 1999
The proof load, as given in tables 7 and 9, shall be applied axially to the bolt in a tensile testing machine. The full
proof load shall be held for 15 s. The length of free thread subjected to the load shall be one diameter (Id).
For screws threaded to the head, the length of free thread subjected to the load shall be as close as practical to one
diameter (Id).
For measurement of permanent extension, the bolt or screw shall be suitably prepared at each end, see figure 2.
Before and after the application of the proof load, the bolt or screw shall be placed in a bench-mounted measuring
instrument fitted with spherical anvils. Gloves or tongs shall be used to minimize measurement error.
To meet the requirements of the proof load test, the length of the bolt, screw or stud after loading shall be the same
as before loading within a tolerance of I 12,5pm allowed for measurement error.
The speed of testing, as determined with a free-running cross-head, shall not exceed 3 mm/min. The grips of the
testing machine should be self-aligning to avoid side thrust on the test piece.
Some variables, such as straightness and thread alignment (plus measurement error), may result in apparent
elongation of the fasteners when the proof load is initially applied. In such cases, the fasteners may be retested
using a 3 % greater load, and may be considered satisfactory if the length after this loading is the same as before
this loading (within the 1 2 5 pm tolerance for measurement error).
Load
X
W
Full-size screw
X
: I :
ri
Load
Full-size boit
Required "sphere to cone" contact between the
measuring points and the centre-drilled holes in the end
of the bolt or screw.
a
d, according to I S 0 273,medium series (see table 10).
Figure 2 - Application of proof load to full-size bolts and screws
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Page 19
EN IS0 898-1 : 1999
8.6 Test for tensile strength under wedge loading of full-size bolts and screws (not studs)
The wedge loading test shall not apply to countersunk head screws.
The test for strength under wedge loading shall be carried out in tensile testing equipment described in IS0 6892
using a wedge as illustrated in figure 3.
The minimum distance from the thread run-out of the bolt to the contact surface of the nut of the fastening device
shall be d. A hardened wedge in accordance with tables 10 and 11 shall be placed under the head of the bolt or
screw. A tensile test shall be continued until fracture occurs.
To meet the requirements of this test, the fracture shall occur in the shank or the free threaded length of the bolt,
and not between the head and the shank. The bolt or screw shall meet the requirements for minimum tensile
strength, either during wedge tensile testing or in a supplementary tensile test without a wedge, according to the
values given for the relevant property class before fracture occurs.
Screws threaded to the head shall pass the requirement of this test if a fracture which causes failure originates in
the free length of thread, even if it has extended or spread into the fillet area or the head before separation.
For product grade C, a radius r1 should be used according to the formula
r1 = rmax + 0,2
in which
hax =
da max - dc min
2
where
r
is the radius of curvature under head;
da
is the transition diameter;
d,
is the diameter of unthreaded shank.
_ I.
a
I íd/2)rnin.
._
d, according to IS0 273, medium series (see table 1O).
Hardness: 45 HRC min.
Radius or chamfer of 45".
Figure 3 -Wedge loading of full-size bolts
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Page 20
EN IS0 898-1 : 1999
Table 10 - Hole diameters for wedge loading tensile test
Dimensions in millimetres
12
13,5
08
36
39
1,6
14
15,5
13
39
42
1,6
Nominal diameter
of bolt and screw
d
Property classes for:
bolts with plain shank length
432d
3.6, 4.6, 4.8, 5.6
6.8, 12.9
5.8, 0.8, 9.8, 10.9
screws threaded to the head and bolts
with plain shank length I, < 2 d
3.6, 4.6, 4.8, 5.6
6.8, 12.9
5.8, 8.0, 9.8, 10.9
mm
ds20
1O"
6"
6"
4"
20 < d G 39
6"
4"
4"
4"
For products with head bearing diameters above 1,7 d which fail the wedge tensile test, the head may be machined
to 1,7 d and re-tested on the wedge angle specified in table 11.
Moreover for products with head bearing diameters above 1,9 d, the 1O" wedge angle may be reduced to 6".
8.7 Impact test for machined test pieces
The impact test shall be carried out in accordance with IS0 83. The test piece shall be taken lengthwise, located as
close to the surface of the bolt or screw as possible. The non-notched side of the test piece shall be located near
the surface of the bolt. Only bolts of nominal thread diameters d > 16 mm can be tested.
8.8 Head soundness test for full-size bolts and screws with L I S 10 mm and with lengths too
short to permit wedge load testing
The head soundness test shall be carried out as illustrated in figure 4.
Page 21
EN IS0 898-1 : 1999
When struck several blows with a hammer, the head of the bolt or screw shall bend to an angle of 90'-ß without
showing any sign of cracking at the shank head fillet, when viewed at a magnification of not less than x 8 nor more
than x 10.
Where screws are threaded up to the head, the requirements may be considered met even if a crack should appear
in the first thread, provided that the head does not snap off.
NOTE 1
For d , and r2 (r2= r , ) , see table 1O.
NOTE 2
The thickness of the test plate should be greater than 2 d.
Figure 4 - Head soundness test
Table 12 -Values of angle ß
Property class
ß
3.6
4.6
5.6
4.8
5.8
6.8
60"
8.8
9.8
10.9
12.9
80"
8.9 Decarburization test: evaluation of surface carbon condition
Using the appropriate measuring method (8.9.2.1 or 8.9.2.2 as applicable), a longitudinal section of the thread shall
be examined to determine whether the height of the zone of base metal ( E ) and the depth of the zone with complete
decarburization (G), if any, are within specified limits (see figure 5).
The maximum value for G and the formulae for the minimum value for E are specified in table 3.
Page 22
EN IS0 898-1 : 1999
1
2
/
4
Key
1
2
3
4
H,
Completely decarburized
Partially decarburized
Pitch line
Base metal
is the external thread height in the maximum material condition.
Figure 5 - Zones of decarburization
8.9.1 Definitions
8.9.1.1
base metal hardness
hardness closest to the surface (when traversing from core to outside diameter) just before an increase or decrease
occurs denoting carburization or decarburization respectively
8.9.1.2
decarburization
generally, loss of carbon at the surface of commercial ferrous materials (steels)
8.9.1.3
partial decarburization
decarburization with loss of carbon sufficient to cause a lighter shade of tempered martensite and significantly lower
hardness than that of the adjacent base metal without, however, showing ferrite grains under metallographic
examination
8.9.1.4
complete decarburization
decarburization with sufficient carbon loss to show only clearly defined ferrite grains under metallographic
examination
8.9.1.5
carburization
result of increasing surface carbon to a content above that of the base metal
8.9.2 Measurement methods
8.9.2.1 Microscopic method
This method allows the determination of E and G.
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Page 23
EN IS0 898-1 : 1999
The specimens to be used are longitudinal sections taken through the thread axis approximately half a nominal
diameter (% d)from the end of the bolt, screw or stud, after all heat-treatment operations have been performed on
the product. The specimen shall be mounted for grinding and polishing in a clamp or, preferably, a plastic mount.
After mounting, grind and polish the surface in accordance with good metallographic practice.
Etching in a 3 O h nital solution (concentrated nitric acid in ethanol) is usually suitable to show changes in
microstructure caused by decarburization.
Unless otherwise agreed between the interested parties, a
x 100 magnificationshall be used for examination.
If the microscope is of a type with a ground glass screen, the extent of decarburization can be measured directly
with a scale. If an eyepiece is used for measurement, it should be of an appropriate type, containing a cross-hair or
a scale.
8.9.2.2 Hardness method (Referee method for partial decarburization)
The hardness measurement method is applicable only for threads with pitches, P 3 1,25 mm.
The Vickers hardness measurements are made at the three points shown on figure 6. Values for E are given in
table 13. The load shall be 300 g.
The hardness determination for point 3 shall be made on the pitch line of the thread adjacent to the thread on which
determinations at points 1 and 2 are made.
The Vickers hardness value at point 2 (HV2) shall be equal to or greater than that at point I (HV,) minus 30 Vickers
units. In this case the height of the non-decarburizedzone E shall be at least as specified in table 13.
The Vickers hardness value at point 3 (HV3) shall be equal to or less than that at point 1 (HV,) plus 30 Vickers
units.
Complete decarburization up to the maximum specified in table 3 cannot be detected by the hardness measurement
method.
Dimensions in millimetres
2
-I
HV,
HV,
2
5
1-0,14
HV, - 30
HV, + 30
Key
1, 2, 3 Measurement points
4
Pitch line
Figure 6
- Hardness measurement for decarburization test
Page 24
EN IS0 898-1 : 1999
Table 13 - Values for Hl and E
12.9
0,230 0,276 0,322 0,368 0,460 0,575 0,690 0,806 0,920 1,151 1,380 1,610 1,841
a For P s 1 mm, microscopic method only.
Calculated on the basis of the specification in 5.16, see table 3
8.1 O Retempering test
The mean of three core hardness readings on a bolt or screw, tested before and after retempering, shall not differ
by more than 20 HV when retempered at a pari temperature 10 "C less than the specified minimum tempering
temperature and held for 30 min.
8.1 1 Surface discontinuity inspection
For the surface discontinuity inspection, see I S 0 6157-1 or I S 0 6157-3 as appropriate.
In the case of test programme A the surface discontinuity inspection is applied to test bolts before machining.
9 Marking
Mechanical fasteners manufactured to the requirements of this International Standard shall be marked in
accordance with the provisions of 9.1 to 9.5.
Only if all requirements in this pari of IS0 898 are met, shall paris be marked and/or described according to the
designation system described in clause 3.
Unless otherwise specified in the product standard, the height of embossed markings on the top of the head shall
not be included in the head height dimensions.
Marking of slotted and cross recessed screws is not usual.
9.1 Manufacturer's identification marking
A manufacturer's identification mark shall be included during the manufacturing process, on all products which are
marked with property classes. Manufacturer's identification marking is also recommended on products which are
not marked with property class.
For the purposes of this part of IS0 898 a distributor marking fasteners with his unique identification mark shall be
considered a manufacturer.
9.2 Marking symbols for property class
Marking symbols are shown in table 14.
Property class
Marking symbol
alb
10.9
3.6
4.6
4.8
5.6
5.8
6.8
8.8
9.8
10.9
3.6
4.6
4.8
5.6
5.8
6.8
8.8
9.8
10.9 10.9b 12.9
12.9
In the case of small screws or when the shape of the head does not allow the marking as given in table 14 the clock
face marking symbols as given in table 15 may be used.
Property class
3.6
Markingsymbols
4.8
4.6
5.6
5.8
'ob
'Q 'Q '0
'0
b
b
Property class
6.8
8.8
9.8
10.9
10.9
12.9
b
a The twelve o'clock position (reference mark) shall be marked either by the manufacturer's identification mark or by a point.
b The property class is marked by a dash or a double dash and in the case of 12.9by a point.
9.3 Identification
9.3.1 Hexagon and hexalobular head bolts and screws
Hexagon and hexalobular head bolts and screws (including products with flange) shall be marked with the
manufacturer's identification mark and with the marking symbol of the property class given in table 14.
The marking is obligatory for all property classes, preferably on the top of the head by indenting or embossing or on
the side of the head by indenting (see figure 7). In the case of bolts or screws with flange, marking shall be on the
flange where the manufacturingprocess does not allow marking on the top of the head.
Marking is required for hexagon and hexalobular head bolts and screws with nominal diameters d 2 5 mm.
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EN IS0 898-1 : 1999
a
Manufacturer's identification mark
b
Property class
Figure 7 - Examples of marking on hexagon and hexalobular head bolts and screws
9.3.2 Hexagon and hexalobular socket head cap screws
Hexagon and hexalobular socket head cap screws shall be marked with the manufacturer's identification mark and
with the marking symbol of the property class given in table 14.
The marking is obligatory for property classes 8.8 and higher, preferably on the side of the head by indenting or on
the top of the head by indenting or embossing (see figure 8).
Marking is required for hexagon and hexalobular socket head cap screws with nominal diameters rf
2
5 mm.
Figure 8 - Examples of marking on hexagon socket head cap screws
9.3.3 Cup head square neck bolts
Cup head square neck bolts with property classes 8.8 and higher shall be marked with the manufacturer's
identification mark and with the marking symbol of the property class as given in table 14.
The marking is mandatory for bolts with nominal diameters d
embossing (see Figure 9).
2
5 mm. It shall be on the head by indenting or
Figure 9 - Example of marking cup head square neck bolts
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EN IS0 898-1 : 1999
9.3.4 Studs
Studs with nominal thread diameters d 2 5 mm, of property class 5.6 and property classes 8.8 and higher shall be
marked by indenting with the marking symbol of the property class as given in table 14 and the manufacturer's
identification mark on the unthreaded part of the stud (see Figure 10).
If marking on the unthreaded part is not possible, marking of property class only on the nut end of the stud is
allowed, see figure 10. For studs with interference fit, the marking shall be at the nut end with manufacturer's
identification marking only if it is possible.
Figure 1O - Marking of studs
The symbols in table 16 are permissible as an alternative identificationof property classes.
Property class
1
5.6
-
Marking symbol
8.8
9.8
10.9
12.9
A
9.3.5 Other types of bolts and screws
If agreed between the interested parties, the same marking systems as described in the previous paragraphs of
clause 9 shall be used for other types of bolts and screws and for special products.
9.4 Marking of bolts and screws with left-hand thread
Bolts and screws with a left-hand thread shall be marked with the symbol shown in figure 11, either on the top of the
head or on the point.
Marking is required for bolts and screws with nominal thread diameters d 2 5 mm.
Figure 11 - Left-hand thread marking
--`,`,,```,,,``,`,,`,,,,`,,,,`,-`-`,,`,,`,`,,`---
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EN IS0 898-1 : 1999
Alternative marking for left-hand thread as shown in figure 12 may be used for hexagon bolts and screws.
Key
s
is the width across flats
k
is the height of the head
Figure 12 - Alternative left-hand thread marking
9.5 Alternative marking
Alternative or optional permitted marking as stated in 9.2 to 9.4 should be left to the choice of the manufacturer.
9.6 Marking of packages
Marking with manufacturer's identification and property class is mandatory on all packages for all sizes.
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EN IS0 898-1 : 1999
Annex A
(informative)
Lower yield stress or stress at 0,2 YOnon-proportional elongation at
elevated temperature
The mechanical properties of bolts, screws and studs will vary in a variety of ways with increasing temperature.
Table A.l, which is for guidance only, is an approximate representation of the reduction in lower yield stress or
0,2 o/o non-proportional elongation which may be experienced at a variety of elevated temperatures. These data
shall not be used as a test requirement.
Temperature O C
+ 20
+ 100
+ 200
+ 250
+ 300
Lower yield stress, ReL or
Property class
stress at 0,2 Yonon-proportional elongation Rp
N/mm2
5.6
300
270
230
215
195
8.8
640
590
540
51O
480
10.9
940
a75
790
745
705
10.9
940
-
-
-
-
12.9
1100
1 020
925
875
825
Continuous operating at elevated service temperature may result in significant stress relaxation. Typically 1O0 h
service at 300 "C will result in a permanent reduction in excess of 25 O h of the initial clamping load in the bolt due to
decrease in yield stress.
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EN IS0 898-1 : 1999
Annex ZA (informative)
Clauses of this European standard addressing essential requirements of the Council
Directive 87/404/EEC
This European standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association and supports essential requirements of the Council Directive
87/404/EEC of 25 June 1987 on the harmonization of the laws of the Member States relating to simple
pressure vessels.
This standard supports the essential safety requirements in Annex I, clause 1.3, of the above directive so
far as bolts and screws made of carbon steel are concerned. The application of this standard is restricted to
bolts and screws of property class 5.6, which is the only one suitable for simple pressure vessels.
Compliance with this standard provides one means of conforming with specific essential requirements of
the Directive.
Annex ZB (normative)
Normative references to international publications
with their relevant European publications
This European Standard incorporates by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed hereafter.
For dated references, subsequent amendments to or revisions of any of these publications apply to this
European Standard only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
Publication
Year
EN
Year
IS0 273
1979
Fasteners - Clearance holes for bolts and screws
EN 20273
1991
IS0 898-2
1992
Mechanical properties of fasteners - Part 2: Nuts with
specified proof load values - Coarse thread
EN 20898-2
1993
IS0 898-5
1998
Mechanical properties of fasteners made of carbon
steel and alloy steel - Part 5: Set screws and similar
threaded fasteners not under tensile stresses
EN IS0 898-5
1998
IS0 898-7
1992
Mechanical properties of fasteners - Part 7: Torsional
test and minimum torques for bolts and screws with
nominal diamet ers 1 mm to 1O mm
EN 20898-7
1995
IS0 6157-1
1988
Fasteners - Surface discontinuities - Part 1: Bolts,
screws and studs for general requirements
EN 26157-1
1991
IS0 6157-3
1988
Fasteners - Surface discontinuities - Part 3: Bolts,
screws and studs for special requirements
EN 26157-3
1991
I S 0 6507-1
1997
Metallic materials - Vickers hardness test - Part 1
Test me thod
EN IS0 6507-1
1997