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Reinforcement Bar Grades

IS 1786:2008 · Table 3 — Mechanical properties of TMT bars

High-strength deformed (HYSD/TMT) bar grades manufactured in India. Higher grade = less steel weight for the same strength, but smaller minimum elongation. Use Fe500 for general RCC, Fe550D for seismic work, Fe415 only where ductility is critical (still allowed by IS 13920 for hoops/links).

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14 items shown

Standard Grades (IS 1786:2008)

Grade	fy	fu	fu/fy	Elong %	Bend Dia	Use
Fe 415	415	485 (min)	1.10 / 1.15 (S/D)	14.5	3d (≤22) / 4d (>22)	Hoops, stirrups, where high ductility needed
Fe 415D	415	500 (min)	1.12 / 1.20	18.0	3d / 4d	Earthquake zones, ductile detailing
Fe 500	500	545 (min)	1.08 / 1.10	12.0	4d / 5d	General RCC — most common in India today
Fe 500D	500	565 (min)	1.10 / 1.12	16.0	4d / 5d	Seismic zones III, IV, V; high-rise buildings
Fe 550	550	585 (min)	1.06 / 1.08	10.0	5d / 6d	High-strength RCC, deep beams, transfer girders
Fe 550D	550	600 (min)	1.08 / 1.10	14.5	5d / 6d	High-strength + ductility (preferred for seismic)
Fe 600	600	660 (min)	1.06	10.0	5d / 6d	Pre-tension precast, special structures

Standard Bar Diameters (mm)

Grade	fy	fu	fu/fy	Elong %	Bend Dia	Use
Available diameters	—	—	—	—	—	6, 8, 10, 12, 16, 20, 25, 28, 32, 36, 40 mm
Standard length	—	—	—	—	—	12 m (most common); 11 m / 13.5 m on order

Quality Tests at Site

Grade	fy	fu	fu/fy	Elong %	Bend Dia	Use
Bend test	Cold	—	—	180°	Per Col. 6	Bar bent over mandrel — no cracks allowed on outer face
Re-bend test	100°C	—	—	45°+23°	5d / 7d	Bend, age, then bend back — no cracks
Tensile test (per heat)	Min 1 sample	—	—	—	—	Verify Fy, Fu, elongation per IS 1608
Mass per metre	± 7% (≤10mm)	± 5% (12–16)	± 4% (>16)	—	—	Tolerance on individual sample
Chemical (C, S, P)	C ≤ 0.30%	S ≤ 0.055%	P ≤ 0.055%	C+Mn/6 ≤ 0.42	—	Restricts brittleness; lower for D-grades

Notes

• Yield strength (fy) is the design value used in IS 456 limit state design

• fu/fy ratio is critical for ductility — D-grade bars have higher fu/fy and elongation

• IS 13920 (ductile detailing) recommends Fe500D or Fe550D for seismic zones III, IV, V

• Never weld TMT bars unless explicitly approved — heat damages the tempered outer skin

• Mass per metre (kg/m) = D² / 162.2, where D is the diameter in mm

• BIS hallmark, manufacturer name, and grade must be rolled onto each bar — verify at delivery

• Stack bars on dunnage off the ground; rust pitting >0.5 mm deep makes bar unfit for use

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