TMT Rods: Everything there is to Know About them

What is the meaning of TMT?

TMT stands for Thermo Mechanically Treated steel. Thermo mechanically treated steel, identified as TMT Steel, can be defined as a modern generation high-strength steel with superior strength, ductility, weld ability, and adaptability that matches the highest state of class standards globally.

What is the conventional length of TMT bars?

TMT steel bars are available with TMT Rods supplier in Baghpat in a variety of diameters, including 8mm, 10mm, 12mm, 16mm, 20mm, 25mm, 32mm, and 36mm, with well-known TMT manufacturing businesses proposing to produce in higher diameters in the future. Bars size 8mm to 10mm are used in slabs and stairs, serving as load-bearing elements in slab houses.

Advantages of TMT Bars

Here are the following benefits one gains out of using TMT Bars:

• Mild steel bars were previously used for small-scale construction due to their low yield strength, but later high yield strength deformed bars were invented to strengthen large-scale construction of heavy structures.
• As the scale of construction increased, and the need for durable structures arose. As a result, TMT bars were invented with better quality in bend ability, weld ability, fire resistance, corrosion resistance and high dimensional tolerance.
• TMT bars have a more durable exterior layer due to the malleable microstructure of the core and the thick crystalline outer surface of TMT steel.
• TMT bars have a higher tensile strength and smaller residual stresses.
• TMT bars have better corrosion resistance properties.
• TMT bars have fewer surface defects compared to HYSD bars because they do not involve torsional stress.
• TMT bars can be used in various types of construction work due to their amazing flexibility and ductility.

As you can see TMT bars offers numerous benefits, so one must opt for Best TMT bars in Baghpat.

What is the difference between twisted rebar and TMT?

Twisted bars and TMT are both high-strength reinforcing steel bars, with the difference being that TMT is hot-treated, whereas twisted bars are cold-treated.

Both are wound in the same process, hot-rolled at a drop temperature of 1200oC to 1000oC.

CTD bar (cold deformed):

1. From the final phase (roll), it is placed in the cooling bed, held for natural cooling, and twisted at room temperature.
2. The bar is stretched to a certain point during twisting whereby the internal grains are in the shape of a crystal, they are crushed, and thus the bars reach the required strength. The longitudinal rib has a spiral shape due to the cold twist.
3. Torstein bars or CTD were the popular names for the reinforcing bars generated by this process (cold twisted deformation). The steel strength in these bars is acquired through cold working rather than by adjusting the chemistry of the steel.
4. The cold work procedure for reinforcing steel consists of stretching and twisting mild steel rolled rebar past the yield plateau and then releasing the load.
5. For many years, these bars dominated the use of reinforcing steel. Due to the reasonable carbon in this reinforcing steel, this steel is weld able.

However, these bars also have the following disadvantages:

• Steel's ductility is affected by the cold twisting process.
• The process breaks down the protective blue oxide; exposes the reinforcing steel surface to corrosion.

Treated thermo mechanical bars (TMT):

This treatment is carried out in three successive stages:

1. Cooling: the hot rolled bar coming out of the end support of the mill is quickly quenched by a special water spray system. The creation of the martensitic edge hardens the bar's surface to a depth optimal for each segment while the core remains hot and austenitic.
2. Automatic tempering: When the rod exits the cooling box, the core remains hot associated to the surface, letting heat flow from the surface and tempering the outer martensitic layer into a Tempered structure Martensite. The core is still austenitic in the stage.
3. Atmospheric cooling: The transformation of the austenitic core into a ductile ferrite pearlite structure takes place in the cooling bed. As a result, the final structure is a perfect blend of a strong outer layer (tempered martensite) and a ductile core (ferrite pearlite).

Because there is no twisting during TMT, there is no twisting tension; hence surface flaws on TMT bars cannot be caused by twisting stress. Therefore, TMT bars resist corrosion better than cold, twisted and warped (CTD) bars.