The current construction of building structures is dominated by reinforced steel. Reinforced steel bars are preferred for their unmatched tensile strength which the concrete is weak to provide and ductility factor, that helps to withstand the load of the structure. There are different grades and different diameters (mm) of the reinforced bars in the current market namely Fe 415, Fe 500, Fe 550 and Fe 600.
Reinforced steel bars have played a major role in the rise of the construction sector by evolving with the demands of the construction sector to provide safer buildings. The use of steel bars as reinforcement started from the 19th century. The rising demands led to the innovation of technologies that refined steel reinforced bars, used for constructing structures.
The construction of a building is virtually incomplete without reinforcement. In construction, Steel is the primary alloy used for reinforcement. There is a reason for that because as we know that concrete is used for the construction of the building, even though it provides the compressive strength, it has weak tensile strength for withstanding induced forces. Therefore by combining reinforced bars, it provides the tensile strength for concrete to withstand induced forces. Also, The properties of thermal expansion for both steel and concrete are approximately the same which is why steel is used as reinforcement.
Part-I of this blog explained the current reinforcement steel trend in India, the TMT steel reinforced bar, the different grades and which grades are preferred. It also explained the most important factor of TMT steel bar which is Ductility. How is it compromised for higher strength. In this blog, the shift towards value-added reinforced steel is explained
Reinforced steel bars or rebars has become the preferred standard for construction of building structures, bridges and many other commercial structures. The most popular among them is the Thermo Mechanically Treated ( TMT) reinforced bars. About 35% of the total steel production in the country was accounted by the reinforced steel industry. Usage of high strength TMT steel rebars has ensured rapid growth within the construction sector.
The previous blog described the alternative environment-friendly route to the conventional blast furnace known as the Corex process. It is a type of smelting reduction process which produces it by using non-coking coal instead of metallurgical coke, which is used by the Blast Furnace. The corex process consists of two parts namely Reduction stage and Melter-gasifier.
This is two of the most used TMT bars when it comes to building homes in India and the average homeowners have a tough time getting their heads around to knowing their difference. So let’s begin with basics itself. Fe stands for Iron, the numbers 500 and 415 is their tensile strength and the ”D” stands for ductility. Here the word signifies the extra ductility which is generally not found in Fe 500. So why would steel companies go to the trouble of making a new grade of TMT bars instead of just promoting Fe 415? In this blog, we will try to find an answer for this conundrum.
First things first, these TMT bars are completely different due to the differences in their manufacturing process. It is where they are used is where the confusion arises. Fe 415 is a fan favourite among the average homeowner and Fe 500 is the choice for home contractors, this is mainly due to their combination of strength and ductility. Fe 500D seems to solve the problem of choosing between either strength or ductility. Fe 500 is perfect medium and small-sized commercial buildings as well as homes, and the Fe 500D can be used to construct both them, the versatility gives the Fe 500D an advantage of over Fe 500 but not over Fe 415.
Fe 415 is naturally more ductile than Fe 500D, while Fe 500D may seem like a combination of strength and ductility, it actually compromises between them. With Fe 415 homeowners get more ductility which can withstand earthquakes and other natural disasters. Fe 415 with its superior ductility can be made into shapes such as columns, slabs and other shapes. Fe 415 can be easily bent without needing the use for any bar bending and bar cutting machines as well. This significantly reduces the cost associated with building a home.
The TMT in TMT Bars stand for Thermo-Mechanically Treated, it is a process of rapidly cooling down bars in the molten state. This cooling down process is either done spraying water at regular intervals. This regular interval will further define the characteristics of the bars. This interval of quenching of bars will give rise to different grades of TMT bars in fact. The goal here is to have a solid and hard outer surface with a pliable inner core. This outer shell is coated with a protective film, making them resistant to corrosion and rust, making them apt for constructing sensitive structures such as high rise residential buildings and bridges in humid areas. TMT bars and different Steel Grades.
Where It’s Used
When building a home, a common man looks for a home which will last a long time, wants to have his/her influence on the designs and doesn’t have a lot of money to throw around. To accommodate these needs, the common looks to Fe 415 and Fe 500. These TMT bars have the ability to tick all the boxes of expectations and demands of the common man such as design influence, cost dependability, and maximum usage of the available space. The reason why these bars have to say even space is a concern is this, even though the number of TMT bars needed may reduce but these bars are purpose made for small structures.
TMT bars of the same grade usually have more than one type, while it is uncommon to hear about Fe 415D or Fe 415S. One must surely be heard of Fe 500 and Fe 500D, here Fe stands for iron, 500 stands for the tensile strength and D stands for ductility. Other than the names they also have a different chemical composition as well. When talking about carbon content Fe 415 has a maximum per cent 0.30 carbon while Fe 415 D and Fe415 S has a maximum carbon per cent of 0.25.