Fe 500, Fe 500D and Fe 550D in IS 1786
| Property | Fe 500 | Fe 500D | Fe 550D |
|---|---|---|---|
| Minimum 0.2% proof stress / yield stress | 500 N/mm² | 500 N/mm² | 550 N/mm² |
| Minimum tensile strength | 1.08 × yield, not less than 545 N/mm² | 1.10 × yield, not less than 565 N/mm² | 1.08 × yield, not less than 600 N/mm² |
| Minimum elongation | 12.0% | 16.0% | 14.5% |
| Minimum total elongation at maximum force | Not specified | 5% | 5% |
| Maximum carbon | 0.30% | 0.25% | 0.25% |
| Maximum sulphur | 0.055% | 0.040% | 0.040% |
| Maximum phosphorus | 0.055% | 0.040% | 0.040% |
| Maximum sulphur + phosphorus | 0.105% | 0.075% | 0.075% |
Limits of the standard. The mill test certificate shows the actual values for each heat.
What the extra ductility does
Elongation is how far a test piece stretches before it breaks. A bar that stretches 16% instead of 12% absorbs more energy and bends further before it snaps, which is what you want when a structure is overloaded or shaken.
Lower carbon, sulphur and phosphorus make the D bar easier to bend without cracking and easier to weld. The larger tensile-to-yield margin means the bar keeps gaining strength after it starts to yield instead of giving way at once.
Five checks when TMT bars arrive
- Marking: look for the grade (for example 500D) rolled onto the bar, and the BIS (ISI) mark and licence number on the bundle tag.
- Test certificate: ask for the mill test certificate and match its heat or cast number to the tag.
- Weight: weigh a full 12 m rod and compare it with the nominal weight (8 mm: 4.74 kg, 12 mm: 10.67 kg). A bar much lighter than nominal is thinner than it should be.
- Surface: light brown surface rust is normal; flaking, pitted rust is not.
- Bend: bend a short offcut sharply; the outside of the bend should show no cracks. This is a site check, not the IS 1786 bend test.
From our team
Notes, photos and examples added by the M&B Chetty team, with the author and the date.
TMT price and where it comes from
| Diameter | Per kg | Per 12 m rod |
|---|---|---|
| 8 mm | ₹58.85 per kg | ₹279 per 12 m rod |
| 10 mm | ₹57.85 per kg | ₹429 per 12 m rod |
| 12 mm | ₹56.85 per kg | ₹607 per 12 m rod |
| 16 mm | ₹56.85 per kg | ₹1,078 per 12 m rod |
GST on steel bars is 18%, shown on the invoice.
Our TMT bars come direct from factories in Gummidipoondi SIPCOT and other plants, and are stocked at our yards in Madhavaram, Uthukottai, Vengal Koot Road, Sathyavedu, Kavaraipettai Main Road and Manellore SIPCOT. Delivery is from the nearest yard holding your sizes.
Send the grade, the diameters and the tonnes or rod counts from your bar-bending schedule. The quote shows both rods and weight.