– Even though the term “structural steel” is used
commonly, there is no accurate definition of this term. Generally
it is used to describe steel which is in the form of a bar, plate
or a shape produced to a particular specification. The specification
involves both chemical and mechanical properties. This particular
material is commonly produced to be used in the construction of
storage tanks, bridges, buildings and other related structural uses.
This material originally was considered to be of low quality but
this no longer is the case. The new specifications require the highest
degree of steel production. In Canada, the most common material
used in producing structural steel is 44w while in other countries
A36 is still the most common.
Structural Steels are defined as to size and product shape by common
practice in the industry and these definitions are published in
present standards. They are:
Flat hot rolled steel
a) – Over 7.87” (200mm) in width and over .2362”
(6mm) in thickness
b) – Over 47.24” (1200mm) in width and over .177”
(4.5mm) in thickness.
Rolled flange sections having at least one dimension of the cross-section
3” (75mm) or greater
Bar Size Shapes:
Rolled flanged sections and angles having a maximum dimension of
cross-section less than 3” (75mm)
Bars – Rounds, Squares and Hexagons and all sizes
Up to 7.87” width and over .1968” thickness
– The term mild steel really has no meaning. Several years
ago people working in the steel industry generally used it to describe
A36 material. Use of this term has now carried over to include 44w.
It should be noted that when using the term “mild steel”
that the person receiving should be working in the same environment.
That is to say that there is an understanding that it is representing
a particular grade such as A36 or 44W. It should not be confused
with 33C which in not intended for any structural end use. It is
a safer practice to specify the exact grade as opposed to a term
when dealing with structural steel. HSLA (High Strength Low Alloy)
has replaced the use of A36 in many market applications.
– This is the most popular ASTM structural steel specification
for carbon steel shapes, plates and bars, for welded and bolted
construction of bridges, buildings and general purposes. It is not
recommended where low temperature toughness is important.
Standard weldable steel normally specified in building construction,
it is not recommended where low temperature toughness is important.
44W can be flame cut, formed, drilled welded and machined by all
Used normally for HSS sections, where specific strength
requirements are required. Suitable for general welded construction
where notch toughness at low temperatures is not a design requirement
50A (350A), 50AT (350AT)
are atmospheric corrosion resistant steels normally used
in bridge constructions for beams and columns. Type A represents
high-strength low-alloy steel with a composition to provide good
atmospheric corrosion resistance and good weldability at high-strength
levels. Used for both painted and unpainted applications. Steel
of this type meet specified strength requirements. Type AT meets
Charpy V-Notch impact requirements. The category of steel required
must be specified.
Intended for the construction of bridges, buildings and
other structures. High-strength low-alloy
A516 GRADE 70
used in the construction of boilers and pressure vessels
are structural steels with a min yield strength of 100/130/140/160
respectively, intended for applications where its high strength
permits weight savings to be made. The plate has very good cold
bending properties with very good weldability. Fulfills the requirements
of ASTM A514, for thickness up to 2 ½”. Guaranteed
impact toughness at -40F (-40C).
– Quench and Tempered Steel is heat-treated to develop
yield strength. This is a cost effective choice for applications
which require high strength, improved notch toughness, superior
weldability and good forming ability, as well as good resistance
to brittle fracture and is suitable for structures where notch toughness
at low temperatures are a design requirement. This meets specific
strength and Charpy V-notch requirements. The category of steel
required must be specified.
QT360 / QT400
– Quench and Tempered Steel that is heat-treated
through hardness for resistance to abrasion. Weldable for structural
sound joints and can be formed with care.
are abrasion resistant plates with a hardness of 400 HD/500
HD, respectively, intended for applications where demands are imposed
on abrasion resistance in combination with impact and/or good cold
bending properties. Very good weldability
Used in the original fabrication and repair of heavy equipment
subject to severe abrasive wear. Common applications would relate
to mining, aggregate, pulp and paper and construction markets.