TMT Bar Manufacturer and Distributor in Kanpur | RHL Profiles limited

Posted by Rajendra Kumar Somani on June 20th, 2022

Savings & Other Benefits to Construction in Use of High Strength TMT Steel Bars 

Steel is an essential element of any civil or construction activity like Houses, Multi Storey, Townships, Malls, Airports, Ports, Dams, Bridges, etc. Steel not only provides strength to any construction but also provides durability and long life.

Each transformation of the steel industry was driven by the growing market need for steel bars with higher strength and elongation. The 21st century has witnessed a rapid increase in the cost of steel products and also brought greater focus on safety and quality norms of construction. This has spurred the demand for the development of TMT bars with properties of high strength and elongation to provide cost savings in the construction by reducing consumption.

Steel researchers across the world have been working hard to develop steel products to meet these specific market needs. This research has led to the development of TMT steel Bars with yield strengths of 500 N/mm 2, 550 N/mm2, and 600 N/mm2. These bars, because of their higher strength than traditional steel bars, are required in lesser quantities, thus, reducing the overall cost of the structure significantly.

The BIS code for IS 1786 (High Strength Deformed Steel Bars And Wires for concrete Reinforcement Specification), IS 13920 (Ductile Detailing of Reinforced concrete structures subjected to Seismic forces - Code of Practice), and IS 456 (Plain And Reinforced Concrete – Code of Practice) incorporated necessary changes to include these latest developments in the field of steel technology.

IS 1786 under its latest revision groups the Steel Bars under the following grades:

Fe 415, Fe 415D, Fe 415S

Fe 500, Fe 500D, Fe 500S

Fe 550, Fe 550D

Fe 600

Reinforcing steel is produced through one or a combination of processes like hot rolling after microalloying, hot rolling followed by cold working, or hot rolling followed by Thermo Mechanical Treatment (TMT process).

TMT Technology

TMT technology involves rapid cooling of hot-rolled bars rolled out of a finishing rolling mill from a temperature of 950-1050°C to 550-600°C using a high-pressure cool water spray system. The bars after quenching are cooled under controlled atmospheric conditions to impart properties based on the size and grade being rolled. The three major steps of the TMT process are as under :

1. QUENCHING: The hot rolled bar coming out of the finishing rolling mill stand is passed through a quenching box where it is rapidly quenched using a high-pressure cool water spray system. The surface of the bar gets hardened to the depth optimized for each section through the formation of a 'Martensitic' rim while the core remains hot and 'Austenitic'.

2. SELF TEMPERING: The bar coming out of the quenching box thus has a hot core compared to the cool outer surface thus allowing the heat to flow from the inner core to the outer surface causing tempering of the outer martensitic rim into "Tempered Martensitic" structure. The core remains "Austenitic" at this stage.

3. ATMOSPHERIC COOLING: The bar is then finished on an Automatic rake type controlled Cooling Bed where uniform atmospheric cooling of each bar takes place under controlled conditions resulting in the transformation of the hot "Austenitic" core of the bar into "Ferrite Pearlite" structure. The resultant final structure of the Bar thus produced consists of a hard and strong outer layer (Tempered Martensitic) with a soft and ductile inner core (Ferrite Pearlite) structure.

Importance of branded steel manufacturer - 

Steel Billet of appropriate chemical composition - Right raw material procurement and selection.

Accurate rolling within close tolerances - Robust and Accurate manufacturing equipment.

Quenching under appropriate water pressure, water temperature, and water volume depending on finishing mill speed, chemical parameters, size, and grade of finished steel - Trained manpower.

Uniform atmospheric cooling on Automatic rake type cooling bed - Right technology.

Testing for Mechanical, and Physical properties in the laboratory - Quality Assurance.

Bundling, tagging, and dispatch as per grade and size of finished TMT Steel - Complete customer service and satisfaction.

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Rajendra Kumar Somani

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Rajendra Kumar Somani
Joined: June 20th, 2022
Articles Posted: 2

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