The engineering
industry is heavily dependant on steel, and it’s used in a huge
range of applications from shipbuilding, the automotive
industry, architecture and machinery building right through to
the common nuts and bolts used in products and equipment used by
each of us in the normal daily run of life.
The Basics
Steel is an alloy of iron that contains a small amount of carbon, much
less than cast iron and usually less than 1.7%. In general the tightly
controlled carbon content determines how easily the steel can be
hardened by heat treatments.
Other alloying elements such as nickel or chromium can
also be added to steel to create a wide variety of desirable
characteristics. Steel is usually separated into at least three groups.
The most common groupings are: mild steels, carbon steels and alloy
steels, each group having different overall attributes.
Suitability to almost any product application can be
found within these groups, although research continues to develop new
alloys within the groups or to ‘fine tune’ those alloys which already
exist.
Steel groups
The mild steels are low in carbon content and are best suited to
applications where heavy loads or stresses are not involved. These
alloys are most suited to use in the manufacture of products where their
easy workability and weldability make them ideal for a range of
fabricated products.
Carbon steels are generally stronger than mild steels.
Their ability to accept hardening treatments is their greatest
attribute.
Alloy steels complete the range, with specific
alloying elements added to make them suitable for a variety of
high-strength and other applications.
Steel standards & specifications
There are literally hundreds of specifications relating to steels.
British, German and American specifications are commonly found in the
UK, however, European harmonisation has added still more.
In practice most steel users will come across a
relatively small number of specifications as part of their work and
indeed many users will know of only a few steels that meet all of their
requirements.
BS 970 was revised in 1970 and the En designation was
replaced by a six digit system. In this system the first three digits
refer to the alloy type, the fourth digit (letter) indicates if the
steel is supplied to Analysis, Mechanical property or Hardenability
requirements and the fifth and sixth digits represent a value that is
100 times the (mean) carbon content.
En3B was not included in this 1970 revision as the
specification was considered too loose. The nearest equivalent to En3B
is generally considered to be 080A15 or similar.
Grade selection
| 080A15 (EN3B) |
230M07 (EN1A) |
655M13 (EN36) |
| 080M40 (EN8) |
605M36 (EN16) |
817M40 (EN24) |
|
