PEEKAY ROLLING MILLS (P) LTD
Thermo Mechanically Treated (TMT)
Thermo mechanically treated
(TMT) steel, can be described as a new-generation-high-strength steel having superior
properties such as weldability, strength, ductility and tensility, which meet the
highest international quality standards.
Features
Resists fire: Withstands temperatures up to
5000
C.
Resists corrosion: The TMT process gives the
bar superior strength and anti-corrosive properties.
Earthquake resistance: The soft
ferrite-pearlite core enables the bar to bear dynamic and seismic loading.
Malleability: TMT bars are most preferred
because of their flexible nature
Enables welding: They have fine welding
features.
Bonding strength: External ribs running across
the entire length of the TMT bar give superior bonding strength between the bar
and the concrete.
Cost-effective: A high tensile strength and
better elongation value gives you great savings
How TMT Steel is prepared:
Under thermo mechanical treatment,
the steel bars are passed through a specially designed water-cooling system
where they are kept till the outer surface of the bars becomes colder while the
core remains hot. This creates a temperature gradient in the bars. When the bars
are taken out of the cooling system, the heat flows from the core to the outer
surface, further tempering of the bars, which helps them attain a higher yield
strength. The resulting heat-treated structure imparts superior strength and
toughness to the bars. The microstructure of the core is a very fine-grained
ferrite and pearlite. TMT bars are also known as 'quenched and tempered rebars',
because of the quenching and tempering processes involved in making the bars.
The production of quality TMT bar depends
on three major factors - quality raw materials, a properly designed and
automated mill, and a well-designed quenching and tempering technology. All
rebars must be purchased based on the properties of yield strength, tensile
strength and elongation values. Deciding the percentage of carbon content in
steel has been a major challenge for engineers. While a minimum level of carbon
content in steel is essential to achieve the required strength, excess carbon
threatens its weldability. In TMT bars, this problem has been eliminated by
restricting the carbon content to 0.2 per cent to attain weldability and
ensuring that its strength is not lost. The joints can be welded by ordinary
electrodes and no extra precautions are required.
The bars come in different lengths, in sizes of
11 to 12 metres and can be customised to the required specifications. TMT bars
that have uniform and concentrated hardened periphery and the softer core will
have the desired tensile strengths coupled with high elongation as required in
seismic zones. Depending on the size and grade, rebars with hardened periphery
of about 15 to 30 per cent of the cross sectional area of the bar are ideal for
civil constructions (constructions of houses, offices, etc.)