Thus, we have Quenched & Tempered TMT Bars having the following Advantages over CTD Bars
High Strength with High Ductility
High Corrosion Resistance
Very High Weld - ability
Very High Bend - ability
High Strength at Elevated Temperature
Bars are Stress Free
Bars have Protective Shield
Lower Manufacturing Cost
International Quality Products
Saving in steel
50% Less Labour in Mills etc.
CHEMISTRY for Quality TMT
Billet / Ingot CHEMISTRY:
One of the major factor that effect that effect the Quality of TMT is CHEMISTRY. The word GIGO aptly describes the process:
Gold in Gold out Also Garbage in Garbage Out
To get good quality TMT ensure that Carbon Equivalent is around 0.38 For our purpose this formula holds good.
Carbon Equivalent Ce = Carbon C + Manganese Mn/6.
Ce = C+ Mn/6.
To get good weld - able quality TMT keep Carbon between 0.20 to 0.25
The implication is
For Carbon 0.20 Mn = 1.08
0.38 = 0.20 + Mn/6
For Carbon 0.25 Mn = 1.78
Mn = [0.38 - 0.20] X 6 = 1.08
0.38 = 0.25 + Mn/6
Mn = [0.38 - 0.25] X 6 = 0.78
With this composition we can assure good Quality TMT which has high strength with High Ductility.
Higher the Carbon, Lower the elongation with same Carbon Equivalent Ce
TMT Process is a Quench & Temper Rolling process.
For prefabrication of TMT bars, lower Ce helps. With high Ce the weld - ability of TMT is effected.
Ce above 0.43 is not advisable for weld-able TMT bars.
In -order to get Premium Quality TMT bars with High Strength and High Ductility, Maintain Ce = 0.38 with the following chemistry for TMT bars.
It is very important to maintain all the elements at the correct percentage.
Any dilution leads to Lowering of Quality and subsequent bar rejection.