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Steel: Properties, Recycling, and High Strength Steel Bars, Exams of Civil Engineering

An overview of steel, its composition, the importance of steel in various industries, and the benefits of steel scrap recycling. It also discusses the differences between tmt and hysd bars, two types of high strength steel bars. Steel is a hard and strong alloy primarily made of iron and carbon, with other elements. It is widely used in construction, infrastructure, automobiles, and machinery due to its high tensile strength and low cost. The document also covers the chemical composition of mild steel and the conditions applicable to steel scrap. Approximately 40% of global steel production comes from steel scrap, which saves resources, reduces co2 emissions, and uses less energy and water compared to producing steel from raw materials.

What you will learn

  • What are the advantages of using high strength steel bars (TMT & HYSD bars)?
  • What is the chemical composition of mild steel?
  • Why is steel an important material in various industries?

Typology: Exams

2017/2018

Uploaded on 10/17/2018

RRS837
RRS837 🇮🇳

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STEEL
Steel is defined as a hard-strong alloy consisting principally of iron and
containing carbon and sometimes other metals.
Steel is an alloy of iron and carbon and other elements. Because of its
high tensile strength and low cost, it is a major component used in
buildings, infrastructure, tools, ships, automobiles, machines, appliances,
and weapons.
Carbon steel is one alloy that is prized in the construction industry for its
hardness and strength. It is typically used to make beams for structural
framework, plates for highway construction, and rectangular tubing for
welded frames trailer beds, and bridges.
Several types of steel are used in construction, depending on the
application. For steel structures, mostly mild steel is used, though there
has been some increase in the use of high tensile steel, and corrosion
resistant steel.
When iron is smelted from its ore, it contains more carbon than is
desirable. To become steel, it must be reprocessed to reduce the carbon to
the correct amount, at which point other elements can be added.To make
steel, iron ore is first mined from the ground. It is then smelted in blast
furnaces where the impurities are removed and carbon is added. In fact, a
very simple definition of steel is "iron alloyed with carbon, in required
proportion."
Chemical Composition of Mild Steel:
CARBON 0.16 to 0.18 % (maximum 0.25% is allowable)
MANGANESE 0.70 to 0.90 %
SILICON maximum 0.40%
SULPHUR maximum 0.04%
PHOSPHOROUS maximum 0.04%
STEEL SCRAP
Steel is, in fact, the most recycled material in the world with scrap accounting
for 40 per cent of the global steel production.
As the metal recycling industry continues to grow, I'm sure there will be even
more uses found for scrap metal in the future. Recycling is just the smart thing
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STEEL

  • Steel is defined as a hard-strong alloy consisting principally of iron and containing carbon and sometimes other metals.
  • Steel is an alloy of iron and carbon and other elements. Because of its high tensile strength and low cost, it is a major component used in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons.
  • Carbon steel is one alloy that is prized in the construction industry for its hardness and strength. It is typically used to make beams for structural framework, plates for highway construction, and rectangular tubing for welded frames trailer beds, and bridges.
  • Several types of steel are used in construction, depending on the application. For steel structures, mostly mild steel is used, though there has been some increase in the use of high tensile steel, and corrosion resistant steel.
  • When iron is smelted from its ore, it contains more carbon than is desirable. To become steel, it must be reprocessed to reduce the carbon to the correct amount, at which point other elements can be added.To make steel, iron ore is first mined from the ground. It is then smelted in blast furnaces where the impurities are removed and carbon is added. In fact, a very simple definition of steel is "iron alloyed with carbon, in required proportion."

Chemical Composition of Mild Steel:

  • CARBON 0.16 to 0.18 % (maximum 0.25% is allowable)
  • MANGANESE 0.70 to 0.90 %
  • SILICON maximum 0.40%
  • SULPHUR maximum 0.04%
  • PHOSPHOROUS maximum 0.04%

STEEL SCRAP

Steel is, in fact, the most recycled material in the world with scrap accounting for 40 per cent of the global steel production. As the metal recycling industry continues to grow, I'm sure there will be even more uses found for scrap metal in the future. Recycling is just the smart thing

to do.The only problem is that since the industry is labour-dependent and unorganised, safety norms are often ignored.

Facts Regarding Recycling Of Steel Scrap

The following are the facts associated with steel scrap and its recycling:

  • Almost 40 % of the global steel production is made from steel scrap. Around 500 million tons of steel scrap is being used annually for the production of steel.
  • Recycling of one ton of steel saves 1.4 tons of iron ore, 0.40 tons of coal, and 0.055 tons of limestone.
  • CO 2 emissions are reduced by 58 % through the use of steel scrap.
  • Recycling one ton of steel scrap saves 2.3 Cu m of landfill space.
  • Recycling of steel scrap uses 75 % less energy compared to creating steel from raw materials.
  • Steel scrap recycling uses 90 % less virgin materials and 40 % less water. It also produces 76 % fewer water pollutants, 86 % fewer air pollutants and 97 % less mining waste.

General Conditions Applicable To Steel Scrap

The following are the general conditions which are applicable to steel scrap:

  • All the grades of steel scrap shall not contain more than 1 % by weight of iron.
  • Steel scrap is to be free from excessive rust, corrosion, dirt, oil, or grease.
  • Steel scrap is to be free of hazardous materials, such as, but not limited to oil filled devices, explosives, radioactive materials, military scrap including fire arms, and ammunition casting etc.
  • Steel scrap shall not include pressurized, closed or insufficiently open containers of all origin since this can cause explosion.
  • Steel scrap shall not have material which are having radioactivity in excess of the ambient level of radioactivity.
  • Steel scrap shall be free of non-metallic materials, insulation material, excessive iron oxide in any form, except nominal amounts of surface rust arising due to outside storage of the prepared scrap under normal atmospheric conditions.
  • Steel scrap is to be free of all but negligible amounts of non-ferrous metals and such as aluminium, zinc, tin in any form, and lead and lead containing materials. It shall be free of visible metallic copper and free of all material which is having high dissolved copper content.
  • (^) Steel scrap shall be free of the alloyed steels as well as stainless steels

most importantly Bendability. In a physically perfect world, HYSD would be the better choice but due to reasons listed below, we can see how TMT bars are a better choice.

TMT Bars Are Better Because:

  • (^) TMT bars do not surface flaws when compared with HYSD bars as unlike HYSD bars, as the manufacturing process in the TMT bars does not involve twisting or torsional stress.
  • When compared with TMT bars, HYSD bars increase the consumption of steel by 8% to 11% when used in the same construction.
  • (^) TMT bars come with a stronger external layer, something which is missing in HYSD due to ductile nature of the core and hard crystalline surface of TMT steel.
  • When compared with TMT bars, HYSD bars cannot provide flexibility and ductility, thus limiting their use in different types of construction works.
  • TMT bars have less residual stress due to the better manufacturing process and have better tensile strength when compared with HYSD bars.
  • TMT bars are effective in earthquake-prone zone and cope better with sudden load surges and absorption when compared with HYSD bars.
  • (^) TMT bars are more corrosion resistant when compared with HYSD bars, this is mainly due to rapid quenching and tempering used in TMT bar manufacturing process.