Ductile Grades of steel TMT rebars, a new generation of high-strength reinforcing steel bars have been developed which is used in all high-grade construction with safety and performance under adverse conditions. High ductility and yield strength are the distinguishing features of these steel TMT bars (Fe 550 & Fe 550 D). The symbol 'D' stands for ductility.

Both Fe 550 and Fe 550 D of National TMT bars are superior grades, same in strength, and ideal for different types of construction projects. The only difference from the perspective of mechanical properties is that the Fe 550 D grade TMT bar has better flexibility than the Fe 500 grade. Greater flexibility/ductility implies more elongation capability to bear more number of oscillations which can arise due to the impact of storms / high and wild wind speed, t remor s , earthquakes and so, guarantees a long life cycle for the constructions.[The elongation capacity of Fe 500 is 12% Min whereas for Fe 550 D it is 14.5 % min as per IS 1786:2008.]

Chemical st ructure decides the best prolongation in TMT rebar. Fe 550D has lower quantities of carbon, sulphur, and phosphorus thus guaranteeing simpler and better weldability, helps in preserving the steel, and makes these bars exceptionally worthy for a wide range of construction purposes