STEEL

STEELAS A BUILDING MATERIAL

INTRODUCTIONSteelis analloyofironand a small amount ofcarbon.On the basis of carbon content, steel forms an intermediate stage between cast iron and wrought iron.In steel, carbon content varies from anything below 0.25% to 1.5% maximum. It is due to the fact that carbon if in access of 1.5%, does not combine with iron and it is present as free graphite.The steel becomes harder and tougher as its carbon content goes on increasing.Steel is suitable for all construction purposes in general as it can take both compressive and tensile stresses.MANUFACTURING PROCESSInmetalworking,rollingis ametal formingprocess in which metal stock is passed through one or more pairs of rolls to reduce the thickness and to make the thickness uniform. Rolling is classified according to the temperature of the metal rolled.HOT ROLLING : If the temperature of the metal is above it recrystallizationtemperature, then the process is termed as hot rolling.Hot rolled mild steel seems to have a wider tolerance for amount of included carbon than cold rolled, making it a bit more problematic to use. Hot rolling is used mainly to producesheet metalor simple cross sections, such asrail tracks.COLD ROLLING:If the temperature of the metal is below its recrystallization temperature, the process is termed ascold rolling (mild steel).

Roll formingA rolling schematic Cold rolled and hot rolled steel

Roll bendingPRESSED STEELSheet steel made into curved sections by press forming. It is often used in the construction of the frame and forks.Thin steel plates shaped by mechanical means such as brake pressing.

PROPERTIES OF STEEL AS A STRUCTURAL DESIGN MATERIAL1. High strength/weight ratio. Steel has a high strength/weight ratio. Thus, the dead weight of steel structures is relatively small. This property makes steel a very attractive structural material fora. High-rise buildingsb. Long-span bridgesc. Structures located on soft groundd. Structures located in highly seismic areas where forces acting on the structure due to an earthquake are in general proportional to the weight of the structure.PROPERTIES OF STEEL AS A STRUCTURAL DESIGN MATERIAL2. Ductility: Steel can undergo large plastic deformation before failure, thus providing a large reserve strength. Properly designed steel structures can have high ductility, which is an important characteristic for resisting shock loading such as blasts or earthquakes. A ductile structure has energy-absorbing capacity and will not incur sudden failure. It usually shows large visible deflections before failure or collapse.3. Predictable material properties: Steel in fact shows elastic behavior up to a relatively high and usually well-defined stress level. Also, in contrast to reinforced concrete, steel properties do not change considerably with time.

PROPERTIES OF STEEL AS A STRUCTURAL DESIGN MATERIAL4. Speed of erection. Steel structures can be erected quite rapidly. This normally results in quicker economic payoff.5. Quality of construction. Steel structures can be built with high-quality workmanship and narrow tolerances.6. Adaptation of prefabrication. Steel is highly suitable for prefabrication and mass production.7. Repetitive use. Steel can be reused after a structure is disassembled.8. Expanding existing structures. Steel buildings can be easily expanded by adding new bays or wings. Steel bridges may be widened.ITS DISADVANTAGES1. General cost. Steel structures may be more costly than other types of structures.2. Fireproofing. The strength of steel is reduced substantially when heated at temperatures commonly observed in building fires. Also, steel conducts and transmits heat from a burning portion of the building quite fast. Consequently, steel frames in buildings must have adequate fireproofing.3. Maintenance. Steel structures exposed to air and water, such as bridges, are susceptible to corrosion and should be painted regularly. Application of weathering and corrosion-resistant steels may eliminate this problem.4. Susceptibility to buckling. Due to high strength/weight ratio, steel compression members are in general more slender and consequently more susceptible to buckling than, say, reinforced concrete compression members. As a result, considerable materials may have to be used just to improve the buckling resistance of slender steel compression members.

USES OF STEELNAME OF STEELCARBON CONTENTUSESMild steelUpto 0.1%Motor body, sheet metal, tin plateMedum carbon steelUpto 0.25%Boiler plates, structural steel, etc.Upto 0.45%Rails, tyres, etc.Upto 0.6%Hammers, large stamping and pressing dies.High carbon steel or hard steelUpto 0.75%Sledge hammers, springs stamping dies, etc.Upto 0.9%Miners drills, smiths tools, stone masons tools, etc.Upto 1%Chisels, hammers, saws, wood working tools, etc.Upto 1.1%Axes, cutlery, drills, knives, picks, punches, etc.ReferencesEngineering materials- Rangwalahttp://hcgl.eng.ohio-state.edu/~ceg532/chap1/chap1_2.htmhttp://en.wikipedia.org/wiki/Rolling_(metalworking)http://www.steelconstruction.info/Steel_material_propertiesGROUP 4Disha Chatrath(060)Adrish Naskar(062)Surai Soren(064)Atul Kumar(066)Abhinav Bhatnagar(068)Himani Thakur(070)Nipun Prabhakar(072)Smriti Gupta(074)Priyank Soni(076)