Property
class
Material and treatment
Chemical composition limits
(check analysis) %  (m/m)
Tempering
temperature ℃
C
P
S
B a
min. 
max.
max.
max.
max.
min.
3.6 b
Carbon steel
\
0,20
0,05
0,06
0,003
\
4.6 b
\
0,55
0,05
0,06
0,003
\
4.8 b
5.6
0,13
0,55
0,05
0,06
0,003
\
5.8 b
\
0,55
0,05
0,06
6.8 b
8.8 c
Carbon steel with additives (e.g. B, Mn or Cr) quenched and tempered
0,15 d
0,40
0,035
0,035
0,003
425
Carbon steel quenched and tempered
0,25
0,55 
0,035 
0,035
9.8
Carbon steel with additives (e.g. B,  Mn or Cr)
quenched and tempered
0,15 d
0,35
0,035 
0,035
0,003
425
Carbon steel quenched and tempered
0,25
0,55
0,035 
0,035
10.9 ef
Carbon steel with additives (e.g.  B, Mn or Cr)
quenched and tempered
0,15 d
0,35 
0,035 
0,035
0,003
340
10.9 f
Carbon steel quenched and tempered
0,25
0,55
0,035 
0,035
0,003
425
Carbon steel with additives (e.g. B, Mn or Cr)
quenched and tempered
0,20 d 
0,55
0,035 
0,035
Alloy steel quenched and tempered g
0,20
0,55
0,035 
0,035
12.9,h i
Alloy steel quenched and tempered g
0,28 
0,50
0,035 
0,035
0,003
380


a. Boron content can reach 0,005 %provided that non-effective boron is controlled by addition of titanium and/or aluminium.
b. Free cutting steel is allowed for these property classes with the following maximum sulfur, phosphorus and lead
contents: sulfur 0,34 %; phosphorus 0,11 %; lead 0,35 % .
c.  For nominal diameters above 20 mm the steels specified for property class 10.9 may be necessary in order to achieve
sufficient hardenability.
d.  In case of plain carbon boron steel with a carbon content below 0,25 % (ladle analysis); the minimum manganese
content shall be 0,6 %for 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 10.9
as specified in table 3 shall be met by 10.9. however, its lower tempering temperature gives it different stress relaxation
characteristics at elevated temperatures.
f.  For the materials of these property classes, it is intended that there should be a sufficient hardenability to ensure a structure
consisting of approximately 90 %martensite in the core of the threaded sections for the fasteners in the "as-hardened" condition
before tempering.
g. This alloy steel shall contain at least one of the following elements in the minimum quantity given: chromium 0,30 %, nickel
0,30 %, molybdenum 0,20 %, vanadium 0,10 %. 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
individual limit values shown above for the two, three or four elements concerned. _
h. 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.

Tags: EN ISO 898-1