Difference Between TMT and TOR Steel [A Complete Guide]

This blog post explores the difference between TMT and TOR steel. After reading this, you will be clear that why TMT bar is preferred over TOR steel, what are the advantages of TMT bar over TOR steel and how TMT bars captured the market of reinforcing steel bars.

There are different types of steel bars used in the construction industry for various purposes. The type of steel bar used varies depending on geographical and environmental factors. TMT bars and TOR steel bars are the two big names among them.

TMT steel bar and TOR steel bar, both have unique features and are used for reinforcement purpose in RCC structures like building foundation, beam, column, slab, roof, wall paneling, concrete bridge deck etc. Both are come in various sizes of 6mm to 50mm in different grades.

Till the 1990s, TOR steel were widely used for reinforcement purpose. But in these days TMT steel bars are mostly used for reinforcement purpose in RCC construction and proudly preferred over TOR steel.

Difference Between TMT and TOR Steel

TMT bars and TOR steel both are the types of steel bars used in construction for reinforcement purpose. But there are some advantages of TMT bars over TOR steel. The features given below show the difference between TMT and TOR steel and also explain why TMT is preferred over TOR steel.

A. Manufacturing Process

The process through which both TMT bars and TOR steel are manufactured are different. TMT bars are manufactured by renowned Thermo Mechanically Treatment process. It has tough outer core with soft inner core and rib pattern on the surface. While TOR steel is manufactured by cold twisting and deformation after undergoing the mandatory heat treatment. It has deformed surface.

B. Tensile Strength & Yield Strength

TMT bars have significantly more tensile strength and yield-strength as compared to TOR steel. So TMT bars can withstand the external force and stress better than TOR steel.
Using TMT bar for the same construction work would require 20% less steel quantity as compared to using TOR steel. For example, if the total steel consumption in a construction project using TMT bars is 500 tonnes, the total steel consumption for the same project using TOR steel would be 600 tonnes.

C. Elongation

Elongation is the ability of a material to elongate before failure occurs. This is the important factor to decide the ductility of material. Higher the elongation, the higher will be ductility of material. TMT bars feature hard outer layer and soft inner-core.
Hence TMT bars have higher elongation as well as ductility which makes building structures strong and flexible and protects them from natural calamities like earthquakes. While TOR steel bars do not have that much elongation as compared to TMT bars.

D. Ductility

Ductility is the ability of a material to deform, without collapsing even after reaching the failure load. TMT bars have superior ductility as compared to TOR Steel which protect building structures from structural collapse.

E. Bendability

Though both TMT bars and TOR steel have a good level of bendability. TOR steel is susceptible to re-bend breakage and can break when re-bending. On the other hand, TMT steel bars possess a hard outer core and soft inner core which allows greater elasticity to steel and effectively eliminates the possibility of breakage during the re-bend process.
Hence, TMT bars have higher bendability and re-bendability which allows them to be further bent to obtain various shapes thus making them easier to work with.

F. Weldability

Weldability of steel is decided by the amount of carbon content in it. Lower the carbon higher the weldability of steel. TMT bars have lower carbon content than TOR steel. Thus, TMT bars are highly weldable as compared to TOR steel.

G. Bonding

TMT bars have uniform ribbed pattern on the entire surface and TOR steel has deformed surface. The uniform ribbed pattern of TMT bars allows for superior bonding strength with concrete but the deformed surface of TOR steel does not. Hence TMT bars provide greater strength to concrete structures and also increase their longevity.

H. Corrosion Resistance

Chloride ions are present in high concentration in TOR steel which makes it prone to corrosion and rust. Whereas the absence of chloride ion in TMT bars makes it very highly rust and corrosion-resistant and thus ideally suitable for construction purposes in humid and coastal areas. During any construction work, TMT bars can be exposed to water for a long time without getting affected.

I. Earthquake Resistance

TMT Bars are intrinsically hard and strong than TOR steel. Although TOR steels are strong, they gradually soften over time which makes them vulnerable to earthquake shocks. On the other hand, TMT bars with their soft inner core and hard outer core have the ability to absorb higher amount of energy released during natural calamity which ensures the safety of building structures against earthquake like natural disasters. In short, TMT bars have higher earthquake resistance than TOR steel.

J. Fire Resistance

TOR steel has low thermal stability and therefore cannot resist high thermal temperatures. On the other hand, TMT bars have high thermal stability and hence are highly thermal/fire resistant. TMT bars can absorb heat from 400 °C to 600 °C. This helps the building structures to stay safe and secure during fire disasters.

K. Durability

The manufacturing process of TMT bars ensures it's highly resistancy to corrosion. During any construction works, the TMT bars can easily stay exposed to water for a longer period without getting affected. On the other hand, traditional steel bars like TOR steel bars do not have anti-corrosive properties like TMT bars and hence remain vulnerable to rusting.

L. Cost

Also, TMT bars are more affordable when compared to TOR steel. Because TMT bars do not go through additional hardening processes and deformation process like TOR steel. So it reduces cost of manufacturing process. In addition, construction projects consume 20% less TMT steel bars than TOR steels.

Let's take a revision on the difference between TMT bars and TOR steel in short.

TMT Bars vs TOR Steel Bars

Thermo Mechanically Treated or TMT bars have tough outer core and soft inner core with uniform ribbed pattern on the entire surface. It has higher strength, ductility, bendability, weldability, corrosion resistance, fire resistance, earthquake resistance and greater durability as compared to TOR steel bar, a type of HYSD (High Yield Strength Deformed) bars.

Supremacy of TMT bars over TOR Steel

TMT (Thermo-Mechanically Treated) Steel Bars offer the perfect optimum balance between tensile strength, yield strength and elongation which is not met by TOR steel bars.

Also, TMT bars are superior to TOR steel bars in terms of ductility, bendability weldability, earthquake resistance, fire resistance, corrosion resistance and durability.

TMT bars are suitable for building earthquake-resistant structures. Not only do they help reduce the cost of construction, but they also reduce damages during any natural calamity and make the structure highly durable. It can't be achieve by using TOR steel bars.

Why TMT Bars are Preferred Over TOR Steel

Though both TOR and TMT bars possess high strength. But TMT bars shows higher elongation, greater resistance to corrosion, fire and earthquake, higher ductility and weldability and better bonding with concrete. That's why TMT bars are more suitable for any concrete construction structures and are preferred over TOR steel bars.

How TMT Bars Captured the Entire Market of Reinforcing Steel Bars

TOR steel came into existence after the brand name ‘Toristeg Steel Corporation’ of Luxembourg. During the time period of 90s, TOR steel was primarily used for reinforcement purposes of construction on a large scale.

By then, TMT bar was introduced in 1979 along with grade Fe 415 and was widely used for construction purposes. Due to its grade's versatility, superior flexibility, high strength and other unique features, TMT bar soon became popular among builders, contractors and house holders. Within a few years, TMT bars captured the entire market of reinforcing steel bars.

FAQs on Difference Between TMT and TOR Steel

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