What is the Manufacturing Process of TMT Bars

What is the Manufacturing Process of TMT Bars?

Thermo-Mechanically Treated Bars or TMT Bars are steel bars manufactured using the thermo mechanical process which results in them having a hard outer core and soft core while retaining their bendability. They bond well with concrete and give it robustness. Therefore, they are used commonly for making reinforced concrete structures that are strong, long-lasting and reasonably earthquake-resistant.

The process of manufacturing TMT bars entails several steps, which are as follows -

1.Turning iron ore to iron - In this process, the primary materials, that are iron ore, coking coal and limestone are put in the top part of a blast furnace while hot air is blown at the bottom of the surface for combustion. The combustion of iron ore creates pig iron, which is free from several of the impurities of iron ore. The limestone helps in separating the iron from impurities and bringing them on the surface in the form of slag.

2.Turning iron into steel - Now, using a ladle, the molten pig iron is poured into a basic oxygen furnace. About 20% of this vessel is also filled with steel. A lance is lowered into the vessel and oxygen is blown through the lance at high pressure. This causes the oxygen to react chemically with the carbon and burn impurities in the iron. The limestone, which is a part of the mix, helps in cleaning the iron further as many impurities such as oxides, silicates, phosphates react with and form slag, or turn into fumes and escape through the top of the furnace. When the slag is separated from molten steel, it is ready to be mixed with other materials and turned into different alloys and casted into any shape. Madhav KRG Group uses the famous Ladle Refining Furnace (LRF) technology which ensures that the steel is free of harmful impurities including phosphorus, sulphur, oxygen, nitrogen and hydrogen. The use of this technology helps in creating 100% ISI tested billets that are ideal for turning into high quality TMT bars.

3.Rolling - After this, the steel is transferred to a Continuous Casting Machine (CCM) in which billets are made.

4.Quenching - Now begins the thermo mechanical treatment whose first step is quenching. Hot-rolled steel bars from the mill undergo quick cooling with a water spray which results in the creation of a hard outer martensitic rim. The core of the bar remains hot and austenitic. These two layers of the TMT bar offer it both strength and ductility.

5. Self-tempering - The steel bars are then allowed to “self-temper”. In this step, the core of the bar, which could not get cooled in quenching, is allowed to transfer its heat to the outer martensitic layer, thereby “tempering” it and enhancing its strength.

6.Atmospheric cooling - Finally, the steel bars are laid on a cooling bed and allowed to rest at normal temperature. This allows the transformation of the soft, inner austenitic core into a ferrite-pearlite structure. Thus, the final product has a hard order layer which is tough and a ductile core.

All the steps of this process have to be performed with precision for best quality TMT bars.

The Madhav KRG Group is one of the top producers of steel and steel-based products in India, and one of their chief products is TMT bars of different grades and sizes. The Madhav KRG uses a superior Ladle Refining Furnace to raise the temperature and ensure that the steel is of the highest quality. This steel has the precise quantity of phosphorus and sulphur, is free from harmful gases such as oxygen, nitrogen and hydrogen, and is free from any defects specified by the BIS. Their TMT bars are used extensively in construction all over India. Each of the TMT bars is checked thoroughly for quality before being delivered to customers. Check this link for finding out more about our TMT bars - https://www.madhavkrggroup.com/tmt-bars.php