Introduction
Since 1988 a new series of 'mandatory'European standards (EN
= Europaischen Normen) has been created, to replace national
standards, such as BS, DIN, SS and NF, throughout 18 countries
of Western Europe. EN are a part of the 'Single Market'
legislation, designed to give equal opportunities for firms to
compete throughout Europe, by harmonising the technical
requirements between countries. The national standards bodies,
of which BSI is one, are required to officially withdraw their
national standards, when an EN is created with the same scope of
application.
Consistent pattern of Standards
The aim is to produce a logical, common pattern,in which
items are standardised in one document only, reference being
made to this document from other standards. For example, tensile
testing methods are standardised in a different document to
material property values, and dimensional tolerances in other
separate standards. Thus, changed requirements need only to be
written into one document.
Implementation of EN
The fact that BSI and the other national
bodies publish EN does not compel people to use them. (Note the
continued use of the BS 'Emergency Number' (also En) series of
steels years after they have been officially replaced.) Only
when suppliers and customers fully accept and understand
European Standards, will it actually happen.
Review of Standards
EN 10025- Hot Rolled Products of non-alloy
steelSteel Names according to EN 10025 in form of ....X(1)
nnn(2) Xn (3) Xn(4).....Ex. S355J2G3
1 S= Structural Steel, E = Engineering steels without
requirements for toughness and weldability
2) nnn = minimum yield Strength Reh (N/mm 2)
3) Impact Property
Testing Temperature = 20 deg. C , 27Joule = JR, 40Joule = KR
Testing Temperature = 0 deg. C , 27Joule = J0, 40Joule = K0
Testing Temperature = -20 deg. C , 27Joule = J2, 40Joule = K2
4) Symbols for special requirements
Deoxidation...G1= Rimming Steel,G2 =Rimming Steel not permitted,
Delivery conditions...G3 Normalised/ Normalised Rolled, G4
Manufactures Discretion.
EN 10027- Designation systems for steel.. Two
systems available EN10027-1
This is a designation system based on names. These names consist
of alphanumerical characters and defines two main groups of
steels
-steels designated on the basis of their use and their
mechanical properties . e.g. S420ML designates a structural
steel(S) with a specified yield strength of 420MPa(420) ,
thermochemically rolled (M) and with impact minimal value
specified between +20 deg.C and -50 deg.C(L).
-steels designated on the basis of their chemical composition
e.g. X2CrNi18-9 designates a stainless steel whose average
contents in carbon, nickel and chromium are about 0.02%, 18% and
9% respectively.
EN10027-2
The other system is a numerical system. The steel numbers
consist of 1 followed by a point and 4 figures. As and example
the steels numbers of the above-mentioned steels are 1.8836 and
1.4307. The steel numbers are allocated by a European
Registering Office. The registering authority has been given to
VDEh in Dusseldorf.
EN 10028 - Flat products made of Steel for
Pressure Purposes
EN 10113 - Hot-rolled products in fine grained structural
steelsSteel Names according to form of ........X(1) nnn(2) X (3)
Xn(4)....Ex. P265GH, P275NL1, S355NL, S355ML
1 S= Structural Steel, P = Steel for Pressure purposes
2) nnn = minimum yield Strength Reh (N/mm 2)
3) Condition
N = Normalised
G = Other Characteristic follows
M = Thermomechanically Rolled
4) Property
H = Elevated Temperature Property. Possible requirements for
tensile test at high temperature.
L= Low temperature property, Impact testing at -10 Deg. C
L1= Low temperature property, Impact testing at -50 Deg. C
L2= Special low temperature property, Impact testing at -50 Deg.
With enhanced requirements
EN10088 Stainless SteelsThe three parts of EN
10088 were published in October 1995.
EN 10088-1 Stainless Steels -Part 1 : List of
Stainless Steels (not for ordering)Part 1 is a new idea, a
reference list of 83 stainless steels, giving chemical
composition, various physical properties, including density and
a general description of the various classes of stainless
steels. It is not intended for the direct placing of orders. The
intention is that the steels required in the various steel
product standards and application standards shall be selected
from this list, as far as possible. They should not be defined
slightly differently unintentionally,nor without a technical
reason for different chemistry. Eventually the list in part 1
will be expanded to include corrosion resistant, hot oxidation
resistant and creep resistant stainless steels, for general and
pressure vessel use, with a cross-reference matrix showing which
steels are in which standards, including the main application
standards. At the moment there are frequent additions to this
information.
EN 10088-2 Stainless Steels Part 2: Technical
Delivery conditions for sheet/plate and strip for general
purposesThis part of EN 10088 gives the properties and other
delivery conditions for flat products for general purposes, i.e.
not for pressure vessels nor for aerospace or other specialised
applications, such as springs, It is used for ordering purposes.
It contains 68 steels, more than BS1449:2 which it largely
replaces.
It is based on a steel naming and numbering system, developed
from the German Werkstoff system, which was the most suitable
system available at the time the first EN standards were
created.
Steel grades are classed as 'standard' or 'special' depending on
how widely available they are, and how wide is their scope of
application. 'Special' grades are likely to be more difficult to
obtain, although the technical requirements are not different in
kind between the two classes. There should be at least one grade
listed, suitable for each general application. Mechanical
properties are significantly more demanding than in BS 1449:2
but quite attainable in practice, with generally higher strength
values, demonstrating the very useful properties of stainless
steels.
Proof stress values at elevated temperatures are included and
properties in the work hardened condition.
EN 10088-3 Stainless Steels -Part 3 Technical
delivery conditions for semi-finished products, bars ,rods and
sections for general purposes.This is the corresponding standard
for long products, but unlike BS970:1 which is replaces it does
not cover forgings. Forgings are being covered in a separate
standard being developed.
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