The Manufacturing Process Of Premium TMT Bars: From Raw Material To Finished Product

The robustness, soundness and stability of any building or structure depend significantly on the quality of the materials used. Thermo-mechanically treated (TMT) bars are a very important and essential component in the construction industry. The bars provide the strength and flexibility required to build robust structures. They are the backbone of reinforced concrete structures, playing a crucial role in ensuring structural integrity. 

There are several stages in the manufacturing process of premium TMT bars, beginning from the selection of raw materials to the finished product. This extensive and all-round process guarantees that the produced bars are of exceptional quality and suitable for a diverse range of construction projects. Now, let’s check out the meticulous manufacturing process of premium TMT bars and have a careful analysis of how these bars are crafted to meet the highest industry standards.

TMT Manufacturing Flow - A Multi-Stage Process 

The production of TMT bars is actually a simple and clear-cut flow, ensuring consistency and quality at each stage. The process commences with the selection of raw materials, prior to their heating, rolling, quenching, self-tempering, and cooling. Every step is crucial in ascertaining the physical and mechanical properties of the finished product, which has to conform to demanding benchmarks to be graded as premium.

Process Compliance - Stage Wise

Raw Material Selection

The journey begins with the selection of top-grade raw materials. The raw materials used for TMT bars are iron ore, coke, or fluxes (limestone and dolomite). Iron ore is the primary source of iron while coke acts as a fuel. The standard of these raw materials directly affects the final product, so stringent tests take place before they enter the manufacturing process. Our state-of-the-art facilities make use of cutting-edge technologies to identify and find out the best batches, guaranteeing a consistent and strong beginning.

Blast Furnace Operation 

To turn iron ore into iron, once the raw materials are selected, they are fed into the top part of a blast furnace while hot air is blown from its bottom for combustion. Here, iron ore is converted into molten iron. The combustion of iron ore produces pig iron, free from many of the impurities of iron ore.         Limestone also helps to remove impurities from the iron ore forming slag. The molten iron generated is then transferred to a basic oxygen furnace for more refinement.

Basic Oxygen Furnace (BOF) And Electric Arc Furnace (EAF)

In the BOF the molten iron undergoes further purification to remove impurities such as Sulfur, Phosphorus, Nitrogen, Hydrogen and excess Carbon. The limestone, which is a part of the mix, also helps in purification as many impurities like oxides, silicates, and phosphates react to form slag or escape in the form of fumes. The metal is then heated again to 1250 degrees Celsius in an EAF for further cleansing.

Continuous Casting Process

The refined molten steel from the EAF is moved to a ladle and then transferred to the continuous casting machine (CCM) to be cast into billets.   This involves pouring the steel into a water-cooled mould, where solidification starts. Continuous Billets coming out from the CCM are sized in accordance with the desired lengths. The process ensures uniformity and consistency in the billets, the intermediate product before being rolled into TMT bars. 

Thermo Mechanical Treatment

Quenching- From the finished mill, the hot-rolled bars are introduced into a water spray system called “Thermex System”. This technology is used in the premium TMT bars manufacturing process to rapidly cool the outer core. This fast cooling creates a hard external surface called a martensitic rim, whereas the hot and Austenitic core remains relatively softer and ductile known as a ferrite-pearlite structure. This special combination of a tough exterior and a ductile core gives TMT bars their high strength and flexibility.  

Self-tempering- The bars leave the Thermex Quenching box with the temperature of the core being higher compared to the surface. So, the heat flows from the core to the surface, causing tempering of the external Martensite layer resulting in a structure called ‘Tempered Martensite’. This is called self-tempering.

Atmospheric Cooling-  After self-tempering is complete, TMT bars are put on a cooling bed, to be cooled at the normal atmospheric temperature. At this point, the austenitic core of the bar attains a ferrite-pearlite structure. This treatment enhances the bar’s tensile strength so that it becomes more ductile and weldable.

MSP Premium TMT Bars are precisely manufactured under a controlled and supervised process, ensuring undeviating compliance with the defined sectional weight range in line with IS 1786 standards. These bars are well known for their extraordinary shine and finish, achieved through the controlled treatment of ultra-clean water with a balanced pH during the course of manufacture. This method improves the bars' physical lusture, while colour-coated end cuts and poly wrap at the bends add a protective layer to safeguard their outstanding shine and finish. Additionally, the consistent and standard rib area (mm²/mm) metrics of the MSP Premium TMT Bars, called the Equispace rib pattern, ensure a strong interlocking bond with the concrete, thereby providing superior stability and strength to any structure.

Adherence To Quality Standards

At MSP Steel, ensuring a superlative standard of TMT bars is of considerable significance. At our Integrated Steel Plant in Raigarh, we deploy state-of-the-art computer-aided testing facilities in our NABL-accredited laboratory to perform all obligatory quality checks. This makes sure that every product batch complies with the BIS 550D Grade specified quality criteria. It’s a three-stage procedure: 1) Raw material inspection, 2) In-process quality checks and 3) Batch testing of finished products.

Our dedication and adherence to the highest standards of quality is backed by a rigid Quality Management System that conforms to ISO 9001:2015 stipulations. This helps us to uphold a benchmark in production standards. At the same time, we are also concerned about the environment and observe Environment Management Norms (14001:2015). Simultaneously, we prioritize the health and safety of our company personnel by obeying Health & Safety Management System (45001:2018) regulations. This facilitates a safe, healthy and conducive working environment for everyone.