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In accordance to the latest revision of IS 1786(2008) Fe 500D is a new introduction of deformed steel bar that has same specified minimum 0.2 percent proof stress/yield stress but with enhanced specified minimum percentage elongation.
Both Fe 500 and Fe 500D are types of TMT steel bars as per the IS: 1786. Fe 500 and Fe 500D have the same 0.2 percent proof stress/yield stress(Min) whereas the tensile strength is increased by 2 percent. Tensile strength(Min) for Fe 500 is 545 MPa and for Fe 500D it is 565 MPa. Fe 500D has enhanced specified minimum percentage elongation i.e 16% whereas Fe 500 has a value of 12%.
Fe – Chemical name of iron
500 – Min yield strength
D – High ductility
Both are TMT bars. (It is a process)
TMT – Thermo Mech Treatment
| Fe500 | Fe500D |
| Min yield strength – 500 N/mm2 or MPa | Same as Fe500 |
| Ultimate tensile strength – 545 N/mm2 | Ultimate tensile strength – 565 N/mm2 |
| Elongation – 12% | Elongation – 16% |
| Carbon – 0.30% | Carbon – 0.25% |
Notation itselfs shows difference between Fe500 & Fe500D bars.
Fe500 describes – TMT bars with 500N/m^2 yield strength.
Fe500D decribes – TMT bars with 500N/m^2 yield strength with ductility property.
Ductility makes bars suitable for earthquake-prone area where it resists sudden shocks and save structure.
Ductility is a property of a material that allows it to elongates after tensile loads; sudden shocks are applied.
The main difference between Fe500 and Fe500D is of ductility.
Both are grades of steel and are High yield strength deformed bars.
Here, 500 is the characteristic tensile strength of steel.
Which is the same in both cases?
Now term D is ductility which is available in Fe500D and not available in Fe500.
So, Fe500D is important in a structure where there are chances of sudden or dynamic+ cyclic or reversible cyclic loading like an earthquake, so in this case, if our structure is durable+ ductile then it will not fail suddenly but will give warning.
This ductility means having more capacity to elongate before failure or rupture.
Ductility is achieved by decreasing carbon content in the steel.
Here fe 500:- ” fe “means that it is made from TMT bars, and the 500 denotes the yield strength of the bars.
whereas
fe 500D:- here “fe” and “500” means the same, but here “D” means for ductility means that these bars are made for more elongation than the normal “fe500” bars.
Fe 500D has minimum percentage elongation i.e 16% whereas Fe 500 has a value of 12% elongation and also the chemical composition point, Fe 500D has 0.25% Carbon (max) as compared to 0.30% (max) in Fe 500. Also, the maximum percentage of Sulphur and Phosphorous are lower in Fe 500D.
Fe 500D with lower quantities of carbon, sulfur and phosphorous, helps in preserving the steel and resisting earthquake shocks in future.
Both Fe 500 and Fe 500D have the same yield strength. But, Fe 500D is more ductile than Fe 500. The ‘D’ in Fe 500D denotes Ductility.
Ductility
This ductile feature comes in as an advantage when the structure is subjected to sudden loads or vibration and makes them ideal for areas prone to earthquakes, cyclones, etc.
