{"id":2816,"date":"2022-12-14T13:57:20","date_gmt":"2022-12-14T08:27:20","guid":{"rendered":"https:\/\/rhlprofiles.com\/blog\/?p=2816"},"modified":"2022-12-14T13:57:20","modified_gmt":"2022-12-14T08:27:20","slug":"savings-other-benefits-to-construction-in-use-of-high-strength-tmt-steel-bars","status":"publish","type":"post","link":"https:\/\/rhlprofiles.com\/blog\/savings-other-benefits-to-construction-in-use-of-high-strength-tmt-steel-bars\/","title":{"rendered":"SAVINGS & OTHER BENEFITS TO CONSTRUCTION IN USE OF HIGH STRENGTH TMT STEEL BARS"},"content":{"rendered":"

STEEL BARS<\/u><\/strong><\/h1>\n

Steel is an essential element<\/strong> of any civil or construction activity like Houses, Multi Storeys, Townships, Malls, Airports, Ports, Dams, Bridges etc.\u00a0 Steel not only provides strength to any construction but also provides durability and long life.<\/p>\n

Transformation in Steel Industry<\/u><\/strong><\/h1>\n

\"\"<\/p>\n

Each transformation of steel industry was driven by the growing market need for steel bars with higher strength and elongation.\u00a0 The 21st<\/sup> century has witnessed a rapid\u00a0 increase in the cost of steel products and also brought greater focus on safety and quality norms of construction.\u00a0 This has spurred the demand for development for TMT bars with properties of high strength and elongation to provide cost savings in the construction by reducing consumption.<\/p>\n

 <\/p>\n

Steel researchers across the world have been working hard to develop steel products to meet these specific market needs.\u00a0 This research has led to development of TMT steel Bars with yield strength<\/a><\/strong> of 500 N\/mm\u00b2, 550 N\/mm\u00b2 and 600 N\/mm\u00b2.\u00a0 These bars, because of higher strength than traditional steel bars, are required in lesser quantity, thus, reducing the overall cost of structure significantly<\/u><\/strong>.<\/p>\n

 <\/p>\n

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 \u2013 Code of Practice) and IS 456 (Plain And Reinforced Concrete \u2013 Code of Practice) incorporated necessary changes to include these latest developments in the field of steel technology.<\/p>\n

 <\/p>\n

IS 1786 under its latest revision groups the Steel Bars under the following grades :<\/p>\n

    \n
  1. Fe 415, Fe 415D, Fe 415S<\/li>\n
  2. Fe 500, Fe 500D, Fe 500S<\/li>\n
  3. Fe 550, Fe 550D<\/li>\n
  4. Fe 600<\/li>\n<\/ol>\n

     <\/p>\n

    Reinforcing steel is produced through one or combination of processes like hot rolling after micro alloying, hot rolling followed by cold working or hot rolling followed by Thermo Mechanical Treatment (TMT process).<\/p>\n

    TMT Technology<\/u><\/strong><\/h2>\n

    TMT technology<\/a><\/strong> involves rapid cooling of hot rolled bars rolled out of a finishing rolling mill from a temperature of 950-1050\u00b0C to 550-600\u00b0C using high pressure cool water spray system.\u00a0 The bars after quenching are cooled under controlled atmospheric conditions to impart properties based on size and grade being rolled.\u00a0 The three major steps of TMT process are as under :<\/p>\n

     <\/p>\n

      \n
    1. QUENCHING :<\/u><\/strong> The hot rolled bar coming out of the finishing rolling mill stand is passed through a quenching box where it is rapidly quenched using high pressure cool water spray system.\u00a0 The surface of the bar gets hardened to the depth optimized for each section through formation of \u2018Martensitic<\/em><\/strong>\u2019 rim while the core remains hot and \u2018Austenitic<\/em><\/strong>\u2019.<\/li>\n<\/ol>\n

       <\/p>\n

        \n
      1. SELF TEMPERING<\/u><\/strong> : 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 \u201cTempered Martensitic<\/strong>\u201d structure. The core still remains \u201cAustenitic<\/em><\/strong>\u201d at this stage.<\/li>\n<\/ol>\n

         <\/p>\n

          \n
        1. ATMOSPHERIC COOLING<\/u><\/strong> : The bar is then finished on a 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 \u201cAustenitic<\/em><\/strong>\u201d core of the bar into \u201cFerrite Pearlite\u201d structure.\u00a0 The resultant final structure of the Bar thus produced consists of a hard and strong outer layer (Tempered Martensitic)<\/strong> with a soft and ductile inner core (Ferrite Pearlite)<\/strong><\/li>\n<\/ol>\n

           <\/p>\n

          Importance of branded steel manufacturer<\/u><\/strong><\/h2>\n
            \n
          1. Steel Billet of appropriate chemical composition \u2013 Right raw material procurement and selection<\/u><\/strong>.<\/li>\n
          2. Accurate rolling within close tolerances \u2013 Robust and Accurate manufacturing equipment<\/u><\/strong>.<\/li>\n
          3. Quenching under appropriate water pressure, water temperature and water volume depending on finishing mill speed, chemical parameters, size and grade of finished steel \u2013 Trained manpower<\/u><\/strong>.<\/li>\n
          4. Uniform atmospheric cooling on Automatic rake type cooling bed \u2013 Right technology<\/u><\/strong>.<\/li>\n
          5. Testing for Mechanical, Physical properties in laboratory \u2013 Quality Assurance<\/u><\/strong>.<\/li>\n
          6. Bundling, tagging and dispatch as per grade and size of finished TMT Steel _ Complete customer service and satisfaction<\/u>.<\/strong><\/li>\n<\/ol>\n

             <\/p>\n

            Properties of different grades of TMT Bars<\/a><\/u><\/strong><\/p>\n

            Chemical Properties<\/u><\/strong><\/p>\n

            The analysis for various grades of steel is done as per relevant part of IS : 228 quality standards and maximum permissible %age of constituents are as below :-<\/p>\n

             <\/p>\n\n\n\n\n\n\n\n\n
            Constituent<\/u><\/td>\nUnit<\/u><\/td>\nFe 500<\/u><\/td>\nFe 500 D<\/u><\/td>\nFe 500 S<\/u><\/td>\n<\/tr>\n
            Carbon (C)<\/td>\n% Max<\/td>\n0.30<\/td>\n0.25<\/td>\n0.25<\/td>\n<\/tr>\n
            Carbon equivalent (CE)<\/td>\n% Max<\/td>\n0.42<\/td>\n0.42<\/td>\n0.42<\/td>\n<\/tr>\n
            Sulphur (S)<\/td>\n% Max<\/td>\n0.055<\/td>\n0.040<\/td>\n0.040<\/td>\n<\/tr>\n
            Phosphorus (P)<\/td>\n% Max<\/td>\n0.055<\/td>\n0.040<\/td>\n0.040<\/td>\n<\/tr>\n
            S + P<\/td>\n% Max<\/td>\n0.105<\/td>\n0.075<\/td>\n0.075<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n