Grades of TMT Steel Bars : Definition, Mechanical Properties, Chemical Composition and Uses

What are in this post?

In this post you will find about different grades of TMT bars, their characteristics like yield strength, ductility, composition, etc. and the most important thing their uses in different projects.

When you go to buy TMT bars, you not only get a choice of different companies in the market, but you also get a choice of different grades of bars. When you are searching for the right TMT bars for your project, a good understanding of these different grades of TMT steel bars is very important.

Different types of projects require different types of TMT bars, depending on the composition, yield strength, dimensions and features they offer. For example, an Fe 415 TMT bar has different characteristics from an Fe 500 not only in yield strength and compositions, but also in utilization and on-site application.

The Bureau of Indian Standards grades TMT steel bars according to their chemical composition and mechanical properties. Indian manufacturers of TMT steel bars adhere to the referenced standards providing additional information regarding the ductility, weldability, corrosion resistance, etc. of the bars.

Table of Contents  (toc)

In market, TMT bars are available in multiple grades, different grades are used by different types of projects like residential, commercial and industrial. Purchasing the right grade of TMT enables you to take advantage of standardization, strength and durability within the project.

The 4 Groups of Standard Grades of TMT Bars

The Bureau of Indian Standards grades TMT steel bars into four groups (IS 1786: 2008).

a) Fe 415, Fe 415D, Fe 415S

b) Fe 500, Fe 500D, Fe 500S

c) Fe 550, Fe 550D

d) Fe 600

A higher grade automatically means lesser utilization of iron & discerning of the rebar quality.

Now read in detail about these TMT bars grades and their compositions, mechanical properties and uses. 

Fe 415 Grade TMT Bar

In TMT bar grade Fe 415, Fe denotes iron (ferrum), numerical figure 415 stand for their minimum required yield strength in N/mm². It's alternatives are available in the form of Fe 415S and Fe 415D.

Uses of Fe 415 Grade TMT Bar

Fe 415 grade TMT bars are commonly used for small-scale construction projects like houses and residential buildings. They have uniform elongation which make them earthquake resistance. Hence they are perfect to build small-load constructions in earthquake-prone areas.

Construction firms may also opt for Fe 415S if they require additional seismic stability or Fe 415D for more ductility requirement.

Mechanical Properties of Fe 415 Grade TMT Bar

Properties	Permissible Value
Yield Strength (N/mm²)	Minimum 415
Tensile Strength (N/mm²)	Minimum 485
Elongation (%)	Minimum 14.5
Ratio (TS/YS)	≥1.10

Chemical Composition of Fe 415 Grade TMT Bar

Constituents	Max. Permissible Percentage
Carbon	0.30
Sulphur	0.060
Phosphorous	0.060
Sulphur + Phosphorous	0.110

Fe 415D Grade TMT Bar

In TMT bar grade Fe 415D, Fe denotes iron (ferrum), numerical figure 415 stand for their minimum required yield strength in N/mm² and D denotes ductility of TMT steel bar. i.e. it is more ductile than Fe 415.

Uses of Fe 415D Grade TMT Bar

As Fe 415, Fe 415D grade TMT bars are commonly used for small-scale construction projects like houses and residential buildings. They have uniform elongation and high level of ductility which make them earthquake resistance. They are highly cost-effective. Hence they are perfect to build small-load constructions in earthquake-prone areas.

Mechanical Properties of Fe 415D Grade TMT Bar

Properties	Permissible Value
Yield Strength (N/mm²)	Minimum 415
Tensile Strength (N/mm²)	Minimum 500
Elongation (%)	Minimum 18.0
Ratio (TS/YS)	≥1.12

Chemical Composition of Fe 415D Grade TMT Bar

Constituents	Max. Permissible Percentage
Carbon	0.25
Sulphur	0.045
Phosphorous	0.045
Sulphur + Phosphorous	0.085

Fe 415S Grade TMT Bar

In TMT bar grade Fe 415S, Fe denotes iron (ferrum), numerical figure 415 stands for their minimum required yield strength in N/mm² and S denotes seismic stability of TMT steel bar.

Uses of Fe 415S Grade TMT Bar

As Fe 415, Fe 415S grade TMT bars are commonly used for small-scale construction projects like houses and residential buildings. They have uniform elongation and high level of seismic stability which make them earthquake resistance. They are highly cost-effective. Hence they are perfect to build small-load constructions in earthquake-prone areas.

Mechanical Properties of Fe 415S Grade TMT Bar

Properties	Permissible Value
Yield Strength (N/mm²)	Minimum 415
Tensile Strength (N/mm²)	–
Elongation (%)	Minimum 20.0
Ratio (TS/YS)	1.25

Chemical Composition of Fe 415S Grade TMT Bar

Constituents	Max. Permissible Percentage
Carbon	0.25
Sulphur	0.045
Phosphorous	0.045
Sulphur + Phosphorous	0.085

Fe 500 Grade TMT Bar

In TMT bar grade Fe 500, Fe denotes iron (ferrum), numerical figure 500 stand for their minimum required yield strength in N/mm².

Uses of Fe 500 Grade TMT Bar

Fe 500 TMT bars offer greater tensile strength than Fe 415 and it is resistant to corrosion. These TMT bars are best suitable for construction of  residential, commercial and multi-store projects and also high-rise projects. The Fe 500 grade TMT bar is generally regarded as a market-standard across many construction projects. 

Its alternatives, Fe 500D and Fe 500S are also popular choices that offer greater ductility and seismic stability respectively.

Mechanical Properties of Fe 500 Grade TMT Bar

Properties	Permissible Value
Yield Strength (N/mm²)	Minimum 500
Tensile Strength (N/mm²)	Minimum 545
Elongation (%)	Minimum 12.0
Ratio (TS/YS)	≥1.08

Chemical Composition of Fe 500 Grade TMT Bar

Constituents	Max. Permissible Percentage
Carbon	0.30
Sulphur	0.055
Phosphorous	0.055
Sulphur + Phosphorous	0.105

TMT Bar Grade Fe 500D

In TMT bar grade Fe 500D, Fe denotes iron (ferrum), numerical figure 500 stand for their minimum required yield strength in N/mm² and D denotes ductility of TMT steel bar. i.e. it is more ductile than Fe 500.

Uses of Fe 500D Grade TMT Bar

As Fe 500, Fe 500D TMT bars offer greater tensile strength and it is resistant to corrosion. So these TMT bars are best suitable for construction of  residential, commercial and multi-store projects and also high-rise projects. Additionally, Fe 500D bars offer greater ductility and they have a superior minimum percentage elongation of 16%, compared to that of Fe 500 at a standard 12%. Hence they are perfect for construction in high seismic activity areas (zone 3, 4 and 5).

Mechanical Properties of Fe 500D Grade TMT Bar

Properties	Permissible Value
Yield Strength (N/mm²)	Minimum 500
Tensile Strength (N/mm²)	Minimum 565
Elongation (%)	Minimum 16.0
Ratio (TS/YS)	≥1.10

Chemical Composition of Fe 500D Grade TMT Bar

Constituents	Max. Permissible Percentage
Carbon	0.25
Sulphur	0.040
Phosphorous	0.040
Sulphur + Phosphorous	0.075

TMT Bar Grade Fe 500S

In TMT bar grade Fe 500S, Fe denotes iron (ferrum), numerical figure 500 stand for their minimum required yield strength in N/mm² and S denotes seismic stability of TMT steel bar.

Uses of Fe 500S Grade TMT Bar

As Fe 500, Fe 500S TMT bars offer greater seismic stability and it is resistant to corrosion. So these TMT bars are suitable for construction of  residential, commercial and multi-store projects and also high-rise projects. Additionally, Fe 500S bars have a superior minimum percentage elongation of 18%, compared to that of Fe 500 at a standard 12%. Hence they are perfect for construction in high seismic activity areas (zone 3, 4 and 5).

Mechanical Properties of Fe 500S Grade TMT Bar

Properties	Permissible Value
Yield Strength (N/mm²)	Minimum 500
Tensile Strength (N/mm²)	–
Elongation (%)	Minimum 18.0
Ratio (TS/YS)	1.25

Chemical Composition of Fe 500S Grade TMT Bar

Constituents	Max. Permissible Percentage
Carbon	0.25
Sulphur	0.040
Phosphorous	0.040
Sulphur + Phosphorous	0.075

TMT Bar Grade Fe 550

In TMT bar grade Fe 550, Fe denotes iron (ferrum), numerical figure 550 stand for their minimum required yield strength in N/mm².

Uses of Fe 550 Grade TMT Bar

Fe 550 grade TMT bars have greater tensile strength. So they are best suitable for large-scale projects like bridges, industrial projects and structures requiring high load-bearing capacities. Fe 550 grade TMT bars are especially impactful in coastal, marine and underground environments as well.

Mechanical Properties of Fe 550 Grade TMT Bar

Properties	Permissible Value
Yield Strength (N/mm²)	Minimum 550
Tensile Strength (N/mm²)	Minimum 585
Elongation (%)	Minimum 10.0
Ratio (TS/YS)	≥1.06

Chemical Composition of Fe 550 Grade TMT Bar

Constituents	Max. Permissible Percentage
Carbon	0.30
Sulphur	0.055
Phosphorous	0.050
Sulphur + Phosphorous	0.100

TMT Bar Grade Fe 550D

In TMT bar grade Fe 550D, Fe denotes iron (ferrum), numerical figure 550 stand for their minimum required yield strength in N/mm² and D denotes ductility of TMT steel bar. i.e. it is more ductile than Fe 550.

Uses of Fe 550D Grade TMT Bar

As Fe 550, Fe 550D TMT bars offer greater tensile strength and it is resistant to corrosion. o they are best suitable for large-scale projects like bridges, industrial projects and structures and heavy underground structures requiring high load-bearing capacities. Additionally, Fe 550D bars offer greater ductility and they have a superior minimum percentage elongation of 14.5%, compared to that of Fe 550 at a standard 10%. Hence they are perfect for construction in high seismic activity areas (zone 3, 4 and 5).

Mechanical Properties of Fe 550D Grade TMT Bar

Properties	Permissible Value
Yield Strength (N/mm²)	Minimum 550
Tensile Strength (N/mm²)	Minimum 600
Elongation (%)	Minimum 14.5
Ratio (TS/YS)	≥1.08

Chemical Composition of Fe 550D Grade TMT Bar

Constituents	Max. Permissible Percentage
Carbon	0.25
Sulphur	0.040
Phosphorous	0.040
Sulphur + Phosphorous	0.075

TMT Bar Grade Fe 600

In TMT bar grade Fe 600, Fe denotes iron (ferrum), numerical figure 600 stand for their minimum required yield strength in N/mm².

Uses of Fe 600 Grade TMT Bar

Fe 600 grade TMT bar is the strongest TMT bar  available in market that is widely used in developing heavy-duty infrastructure projects, expressways, metro projects, plants, towers, commercial properties, bridges, marine facilities, etc. They offer greater tensile strength, high durability and corrosion-resistance. They reduce overall consumption and ensure lesser steel congestion within the reinforcement.

Mechanical Properties of Fe 600 Grade TMT Bar

Properties	Permissible Value
Yield Strength (N/mm²)	Minimum 600
Tensile Strength (N/mm²)	Minimum 660
Elongation (%)	Minimum 10.0
Ratio (TS/YS)	≥1.06

Chemical Composition of Fe 600 Grade TMT Bar

Constituents	Max  Permissible Percentage
Carbon	0.30
Sulphur	0.040
Phosphorous	0.040
Sulphur + Phosphorous	0.075

All these TMT bars are available in market in different sizes like 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 16mm, 20mm, 25mm, 28mm and 32mm and their higher sizes are also customise according to requirement and order.

FAQs

How many grades of steel bars?

There are mainly 4 grades of steel bars available in market.

a) Fe 415, Fe 415D, Fe 415S

b) Fe 500, Fe 500D, Fe 500S

c) Fe 550, Fe 550D

d) Fe 600

How many grades of TMT bars?

There are mainly 4 grades of TMT bars available in market.

a) Fe 415, Fe 415D, Fe 415S

b) Fe 500, Fe 500D, Fe 500S

c) Fe 550, Fe 550D

d) Fe 600

Which grade of TMT bar has the most strength?

Fe 600 grade TMT bar has the most yield strength 600 N/mm² and ultimate tensile strength 600 N/mm².

What is the IS code for grading of steel bars?

IS 1786: 2008 is the IS code for grading of steel bars.

What is the IS code for grading of steel bars?

IS 1786: 2008 is the IS code for grading of TMT bars.

Which grade of TMT bars is best suitable for earthquake prone areas?

Fe 500D and Fe 550D (sometimes manufacturers write it SD) are best suitable for construction in earthquake prone areas.

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