Out
of all the different variations of steel, a hot rolled steel sheet does not
have the strict requirements to be exactly perfect. The process of turning a slab of steel in to
the hot rolled sheet variety plays a major role in the inconsistencies of the
metal. When it comes to producing a hot
rolled product, “as long as it’s in the ball park” can be considered
perfection.
Making hot rolled steel involves
subjecting the steel to heat above its recrystallization temperature, typically
over 1,700 degrees Fahrenheit. As the steel
reaches these temperatures it is capable of being shaped and formed quite
easily. The most popular way of
shaping and forming malleable steel is with a mill process called hot
rolling. Once the steel is heated to the
proper temperatures it is fed through a set of rollers that reduce the
thickness of the steel to a predetermined measurement. This process is somewhat similar to rolling
out bread dough with a rolling pin. By
applying pressure, chemical properties of the steel are spread out creating a
product much larger in size.
After the steel has been through the
rolling mill it is left to cool. As the
steel returns to a solid state, it loses some of its size making it difficult
for hot rolled steel to meet exact measurements. These inconsistencies in size are one of the
reasons hot rolled steel is used in situations where precise shapes and
tolerances are not mandatory.
Surface condition is another aspect of the hot rolled steel that limits its use in projects
where surface is a major factor. A blue
scale finish is left behind from the hot rolling process and it is done
completely by accident. Since this
finish is not controlled, the surface can be somewhat different from sheet to
sheet.
Inconsistencies in the finished
product which is hot rolled steel are not the only reason for it being less
expensive than its cold rolled counterpart.
During the hot rolling process, heating up the steel only occurs
once. In the cold rolling process, the
steel has to be heated and cooled multiple times. This additional processing is the primary
reason why hot rolled steel is less expensive than cold rolled steel.
Hot rolled steel is generally manufactured
for structural components such as I-beams or cross sections for railroad
tracks. Compared to cold rolled steel
where durability, tolerance, and surface condition or vital, it is much less
crucial for hot rolled steel to be precise.
For obvious reasons, sheets of hard
rolled steel just are not the answer.
Sometimes a more durable and exact material better suits the
project. Although, when the time comes
to throw a project together quickly, without a care in the world about surface
condition or strength, hot rolled steel sheets are the answer. Hot rolled steel is fairly inexpensive when
compared to other forms of steel and it is not too difficult to work with.
