TMT Bars

TMT Bars

A-ONE TMT BARS ADVANTAGES

  • A-ONE Lugs & Ribs
  • A-ONE Quality & Strength
  • A-ONE Bend-ability
  • A-ONE Savings on Cost of Steel
  • A-ONE Earthquake Resistance
  • A-ONE Fire Resistance
  • A-ONE Weld-ability
  • A-ONE Bonding with Concrete
  • A-ONE Ductility & Malleability
  • A-ONE Thermal Resistance
  • A-ONE Fire Resistance
  • A-ONE Weld-ability
  • A-ONE Bonding with Concrete

TMT BARS
(Thermo – Mechanical Treatment BARS)

Thermo – Mechanical Treatment is a metallurgical process that integrates work hardening and heat – treatment into a single process.

Process:-

MS Billets are heated to approximate 1100c in a reheat Furnace. Then they are progressively rolled to reduce the billet to the final size and shape of reinforcing bar. After the last rolling stand, the billet moves through a quench Box. The quenching Converts the billet’s surface layer to marten site, and causes it to shrink. The Shrinkage pressurizes the core, helping to form the correct crystal structures. The core remains hot, and austenitic. A microprocessor controls the water flow to the queen box, to manage the temperature difference through the cross-section of the bars. The correct temperature difference assures that all processes occur, and bars have the necessary mechanical properties.

The Bar leaves the quench box with a temperature gradient through its cross section. As the bar cools, heat flows from the bars centre to its surface so that the bar’s heat and pressure correctly tempers an intermediate ring of marten site and bainite.

Finally, the slow cooling after quenching automatically tempers the austenitic core to ferrite and pearlite on the cooling bed.

These bars therefore exhibit a variation in microstructure in their cross section, having strong, tough, tempered marten site in the surface layer of the bar, an intermediate layer of marten site and bainite, and a refined, tough and ductile ferrite and pearlite core.


Comparison Chart

Properties/ Compositions Unit India (IS: 1786) A-ONE GOLD TMT India (IS: 1786) A-ONE GOLD TMT
Mechanical Properties
Grade Unit Fe-500 Fe-500 Fe-500 D Fe-500 D
Proof Stress N/mm² 500 min 530 min 500 min 530 min
Ultimate Stress N/mm² 565 min 645 min 565 min 660 min
Elongation % 12 min 16 min 16 min 18 min
Safety Factor Ratio 1.08 min 1.15 min 1.10 min 1.18 min
Chemical Composition (%)
Carbon % 0.30 Max. 0. 25 Max. 0. 25 Max. 0. 25 Max.
Sulphur % 0. 055 Max. 0. 050 Max. 0. 045 Max. 0. 040 Max.
Phosphorous % 0. 055 Max. 0. 050 Max. 0. 045 Max. 0. 040 Max.
S+P % 0. 105 Max. 0. 095 Max. 0. 085 Max. 0. 075 Max.
Carbon Equivalent % 0. 42 Max. 0. 40 Max. 0. 42 Max. 0. 40 Max.
Si % 0. 10 min 0. 18 Min 0. 10 Min 0. 20 Min

 

Size Of Bar Cor dia IS 1786:2008
Section Weight
Kg/  Mtr.
FOR  A – ONE  STEEL
Section weight
Kg/ mtr
A–ONE  YIELD STRESS No. of pieces Bundle weight
MM
 8
 10
 12
16
 20
 25
32
MM
7.85
 9.75
 11.75
 15.6
 18.5
 24.4
30.94
Min Normal Max
0.367 – 7% 0.395 0.423 + 7%
 0.574 – 7% 0.617 0.660 +7%
0.844 – 5% 0.888 0.932 +5%
 1.500 – 5% 1.578 1.658 + 5%
 2.393 – 3%  2.466 2.539 +3%
3.739 – 3% 3.855 3.970 +3%
6.120 – 3%  6.310 6.499 + 3%
Min Max
 0.367 0.385
0.574 0.590
0.844  0.880
1.500  1.530
 2.400  2.440
3.750 3.800
 6.150  6.300
Min Max
 530  560
 530 560
530 560
530 560
530 550
530 550
525  550
Min
10
7
5
3
2
1
1
Min
44-46 kg
48-50 kg
50-52 kg
54-56 kg
57-59 kg
45-47 kg
75-77 kg