Fe 500, Fe 550 and Fe 550D TMT bars compared
The number in a TMT grade is its minimum yield strength in N/mm². Fe 550 is stronger than Fe 500. The letter D stands for ductility: a D grade stretches further before it breaks and has tighter limits on carbon, sulphur and phosphorus.
Grade comparison under IS 1786
| Grade | Yield strength, minimum | Tensile strength, minimum | Elongation, minimum | Carbon, maximum |
|---|---|---|---|---|
| Fe 500 | 500 N/mm² | 545 N/mm² | 12% | 0.30% |
| Fe 500D | 500 N/mm² | 565 N/mm² | 16% | 0.25% |
| Fe 550 | 550 N/mm² | 585 N/mm² | 10% | 0.30% |
| Fe 550D | 550 N/mm² | 600 N/mm² | 14.5% | 0.25% |
What a higher number gives you
A higher yield strength means each bar carries more load. A design in Fe 550 can use less steel than the same design in Fe 500.
What the D gives you
Higher elongation means the bar bends and stretches further before failing. That matters most where a structure has to absorb movement.
Which grade to buy
The grade is a design decision. Your structural drawing states it, and bars of a different grade should not be substituted without the engineer's approval.
The grade Amrit Steels supplies
All TMT material we supply is Fe 550 or Fe 550D grade, ISI-marked, with test reports.
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WhatsApp us nowFrequently asked questions
What does Fe 550 mean in TMT bars?
Fe stands for iron and 550 is the minimum yield strength of the bar in N/mm².
What does the D mean in Fe 550D?
The D stands for ductility. Fe 550D has a higher minimum elongation, 14.5 percent against 10 percent for Fe 550, and lower limits on carbon, sulphur and phosphorus.
Is Fe 550 stronger than Fe 500?
Yes. Fe 550 has a minimum yield strength of 550 N/mm², against 500 N/mm² for Fe 500.