Architecture technology: Steel
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Politecnico di Torino Torino – School of Architecture Fundamentals of Architectural Technology Prof. Roberto Pagani Arch. Giulia Bonomi Arch. Zang Yu
STEEL Acciaio
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General definitions definiti ons METALS metalli Of all known elements, metals make up the majority. majority. Within periodic table there are five separate families of metals >Alkali metals very reactive metals, none of these used in architecture >Alkaline earth metals magnesium and beryllium are used as alloyins constitutents otherwise not used for architectural applications >First transition metals known for hardness and strength, especially when tungsten, chromium and vanadium are used as alloying agents >Second transition metals iron is major architectural element of this group Nickel is alloyed with copper to produce moneland, with iron and steel to produce the stainless steels >Third transition metals all of these play an architectural role Zinc and copper are sought for their superior stability in atmospheric conditions
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General definitions definiti ons Metals are characterized by a crystalline, compact and homogeneous chemical structure which make them similar to isotropic materials, as they have same physical characteristics in any direction. According to their composition they can be divided into: CAST IRON ghisa
FERROUS or IRONWORKS
STEEL acciaio SOFT IRON ferro dolce crystalline structure
COPPER rame ALLUMINIUM alluminio
NOT FERROUS ZINC zinco amorphous structure
LEAD piombo
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Ferrous metals FERROUS METALS metalli ferrosi They are obtained casting in blast furnaces iron stones at 1900°C, which are further processed. Ferrous metals include alloys of iron and coal, to which other elements are added, in order to convey specific characteristics characteristics to the material. According to the composition of the alloy, alloy, ferrous metals can be divided into: > CAST IRON ghisa high percentage of carbon --> between 2,06% and 4% obtained directly casting iron stones > SOFT IRON ferro dolce obtained with a total decarburetion of cast iron in order to reach very low percentage of iron --> less than 0,1% > STEEL acciaio gained with a partial decarburetion of cast iron in order to reach medium percentage of carbon --> from 2,06% to 0,1% it can also contain less than 1% manganese and small amounts of silicon, phosphorus, sulphur and oxygen
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Ferrous metals Steel can be divided into three more categories: > Carbon steels They contain only carbon and iron and small quantities of impurities. Among these can be included carpentry steels which are normally used in construction and which are classified according to their resistance to tensile strength: Fe 360 --> ultimate strenght ≥ 360 N/mm2 Fe 430 --> ultimate strenght ≥ 430 N/mm2 Fe 510 --> ultimate strenght ≥ 510 N/mm2 Carbon steels are used also to produce metallic bars for concrete steel.
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Ferrous metals > Low-alloy steels addition to carbon steels of small amounts of alloy elements such as chromium, columbium, copper, manganese, molybdenum, nickel, phosphorous, vanadium, zirconium improves some of the mechanical properties. The two main examples of low-alloy steels are ex-ten steel and corten steel which both have: good resistance to tensile stress very high resistance to corrosion good possibility to be welt
> High-strength steels They contain a quantity of alloy elements above 5%. Additional strength is obtained through a fine-grai fine-grained ned crystalline microstructure as opposed to the course graining of simple carbon steel. Among these can be included stainless steel which are very used in construction.
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Ferrous metals The quantity of carbon in the alloy can affect mechanical properties: the highest the percentage is the hardest and resistant the metal is, despite the loos of ductility ductility,, malleability and the possibility to be welt
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Properties PHYSICAL AND MECHANICAL PROPER PROPERTIES TIES Proprietà fisiche e meccaniche dei metalli >
ISOTROPY isotropia
>
CONDUCTIVITY conducibilità
>
FIREPROOF incombustibilità
>
High resistance to tensile strenght good resistance to compression strenght
>
DUCTILITY duttilità
>
RESILIENCE resilienza
>
MALLEABILITY malleabilità
>
HARDNESS durezza
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Properties > DUCTILITY
duttilità
more commonly defined as the ability of a material to deform easily upon the application of a tensile force, or as the ability of a material to withstand plastic deformation without rupture Ductile materials show large deformation before fracture
STEEL Young modulus 2.100.000 daN/cm2 0
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Properties The lack of ductility is often termed BRITTLENESS fragilità Usually, if two materials have the same strength and hardness, the one that has the higher ductility is more desirable The ductility of many metals can change if conditions are altered: an increase in temperature will increase ductility while a decrease in temperature will cause a decrease in ductility and a change from ductile to brittle behavior.
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Properties Cold-working also tends to make metals less ductile. Cold-working is performed in a temperature region and over a time interval to obtain plastic deformation, but not relieving the strain hardening. Minor additions of impurities to metals, either deliberate deli berate or unintentional, can have a marked effect on the change from ductile to brittle behavior. The heating of a cold-worked metal to or above the temperature at which metal atoms return to their equilibrium positions will increase the ductility of that metal. > RESILIENCE
resilienza
attitude of a material to absorb energy (in the form of elastic or plastic deformation) in a short time.
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Properties >MALLEABILITY
malleabilità
property of metals to be shaped or formed into thin sheets, by hammering or pressure, without breaking gold, iron, copper and lead are malleable metals >HARDNESS
durezza
Resistance of metal to plastic deformation, usually by Resistance indentation. However, the term may also refer to stiffness or temper, or to resistance to scratching, abrasion, or cutting. It is the property of a metal, which gives it the ability to resist being permanently, permanently, deformed (bent, broken, or have its shape changed), when a load is applied. The greater the hardness of the metal, the greater resistance it has to deformation. 0
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Properties
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Properties
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Properties PHYSICAL AND MECHANICAL WEAKNESSES Debolezze fisiche e meccaniche dei metalli >
SHRINKABILITY deformabilità
>
Bad behaviour in case of fire
>
Low resistance to CORROSION
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Processings > ROLLING laminazione The process of shaping metal by passing it between rolls revolving at the same peripheral speed and in opposite directions. In steel there are a number of different types of rolling mill for processing the ingot to its finished shape. These are variously known as Cogging mills, Slabbing mills, Billet mills, Bar mills and Strip mills, which produce plate, sections, bars, sheet and strip. hot rolling is the most commonly used process, durgin which metal is heaten at 1100 1300 °C in order to improve its malleability and workability
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Processings cold rolling cold rolling of previously hot rolled strip causes the hardening of the material due to the breaking of the crystalline structure. Higher precision can be reached and better mechanical properties > WIRE DRAWING trafilatura is a metalworking process used to reduce the cross-section of a wire by pulling the wire through a single, or series of, drawing die(s) Drawing is usually performed at room temperature, thus classified a cold working process, but it may be performed at elevated temperatures for large wires to reduce forces
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Processings > EXRTUSION estrusione is a metalworking process similar to wide drawing consisting in pushing the metals through a die of the desired cross-section, after heating the bars at 1100 °C. The cross-sections that can be produced vary from solid round, rectangular, to L shapes, T shapes.
> FORMING stampaggio > BENDING piegatura > FORGING fucinatura
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STEEL Acciaio
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General definitions definiti ons METALS metalli Of all known elements, metals make up the majority. majority. Within periodic table there are five separate families of metals >Alkali metals very reactive metals, none of these used in architecture >Alkaline earth metals magnesium and beryllium are used as alloyins constitutents otherwise not used for architectural applications >First transition metals known for hardness and strength, especially when tungsten, chromium and vanadium are used as alloying agents >Second transition metals iron is major architectural element of this group Nickel is alloyed with copper to produce moneland, with iron and steel to produce the stainless steels >Third transition metals all of these play an architectural role Zinc and copper are sought for their superior stability in atmospheric conditions
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1
2
3
4
0
General definitions definiti ons Metals are characterized by a crystalline, compact and homogeneous chemical structure which make them similar to isotropic materials, as they have same physical characteristics in any direction. According to their composition they can be divided into: CAST IRON ghisa
FERROUS or IRONWORKS
STEEL acciaio SOFT IRON ferro dolce crystalline structure
COPPER rame ALLUMINIUM alluminio
NOT FERROUS ZINC zinco amorphous structure
LEAD piombo
0
1
2
3
4
1
Ferrous metals FERROUS METALS metalli ferrosi They are obtained casting in blast furnaces iron stones at 1900°C, which are further processed. Ferrous metals include alloys of iron and coal, to which other elements are added, in order to convey specific characteristics characteristics to the material. According to the composition of the alloy, alloy, ferrous metals can be divided into: > CAST IRON ghisa high percentage of carbon --> between 2,06% and 4% obtained directly casting iron stones > SOFT IRON ferro dolce obtained with a total decarburetion of cast iron in order to reach very low percentage of iron --> less than 0,1% > STEEL acciaio gained with a partial decarburetion of cast iron in order to reach medium percentage of carbon --> from 2,06% to 0,1% it can also contain less than 1% manganese and small amounts of silicon, phosphorus, sulphur and oxygen
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3
4
1
Ferrous metals Steel can be divided into three more categories: > Carbon steels They contain only carbon and iron and small quantities of impurities. Among these can be included carpentry steels which are normally used in construction and which are classified according to their resistance to tensile strength: Fe 360 --> ultimate strenght ≥ 360 N/mm2 Fe 430 --> ultimate strenght ≥ 430 N/mm2 Fe 510 --> ultimate strenght ≥ 510 N/mm2 Carbon steels are used also to produce metallic bars for concrete steel.
0
1
2
3
4
1
Ferrous metals > Low-alloy steels addition to carbon steels of small amounts of alloy elements such as chromium, columbium, copper, manganese, molybdenum, nickel, phosphorous, vanadium, zirconium improves some of the mechanical properties. The two main examples of low-alloy steels are ex-ten steel and corten steel which both have: good resistance to tensile stress very high resistance to corrosion good possibility to be welt
> High-strength steels They contain a quantity of alloy elements above 5%. Additional strength is obtained through a fine-grai fine-grained ned crystalline microstructure as opposed to the course graining of simple carbon steel. Among these can be included stainless steel which are very used in construction.
0
1
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3
4
1
Ferrous metals The quantity of carbon in the alloy can affect mechanical properties: the highest the percentage is the hardest and resistant the metal is, despite the loos of ductility ductility,, malleability and the possibility to be welt
0
1
2
3
4
2
Properties PHYSICAL AND MECHANICAL PROPER PROPERTIES TIES Proprietà fisiche e meccaniche dei metalli >
ISOTROPY isotropia
>
CONDUCTIVITY conducibilità
>
FIREPROOF incombustibilità
>
High resistance to tensile strenght good resistance to compression strenght
>
DUCTILITY duttilità
>
RESILIENCE resilienza
>
MALLEABILITY malleabilità
>
HARDNESS durezza
0
1
2
3
4
2
Properties > DUCTILITY
duttilità
more commonly defined as the ability of a material to deform easily upon the application of a tensile force, or as the ability of a material to withstand plastic deformation without rupture Ductile materials show large deformation before fracture
STEEL Young modulus 2.100.000 daN/cm2 0
1
2
3
4
2
Properties The lack of ductility is often termed BRITTLENESS fragilità Usually, if two materials have the same strength and hardness, the one that has the higher ductility is more desirable The ductility of many metals can change if conditions are altered: an increase in temperature will increase ductility while a decrease in temperature will cause a decrease in ductility and a change from ductile to brittle behavior.
0
1
2
3
4
2
Properties Cold-working also tends to make metals less ductile. Cold-working is performed in a temperature region and over a time interval to obtain plastic deformation, but not relieving the strain hardening. Minor additions of impurities to metals, either deliberate deli berate or unintentional, can have a marked effect on the change from ductile to brittle behavior. The heating of a cold-worked metal to or above the temperature at which metal atoms return to their equilibrium positions will increase the ductility of that metal. > RESILIENCE
resilienza
attitude of a material to absorb energy (in the form of elastic or plastic deformation) in a short time.
0
1
2
3
4
2
Properties >MALLEABILITY
malleabilità
property of metals to be shaped or formed into thin sheets, by hammering or pressure, without breaking gold, iron, copper and lead are malleable metals >HARDNESS
durezza
Resistance of metal to plastic deformation, usually by Resistance indentation. However, the term may also refer to stiffness or temper, or to resistance to scratching, abrasion, or cutting. It is the property of a metal, which gives it the ability to resist being permanently, permanently, deformed (bent, broken, or have its shape changed), when a load is applied. The greater the hardness of the metal, the greater resistance it has to deformation. 0
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Properties
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Properties
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Properties PHYSICAL AND MECHANICAL WEAKNESSES Debolezze fisiche e meccaniche dei metalli >
SHRINKABILITY deformabilità
>
Bad behaviour in case of fire
>
Low resistance to CORROSION
0
1
2
3
4
3
Processings > ROLLING laminazione The process of shaping metal by passing it between rolls revolving at the same peripheral speed and in opposite directions. In steel there are a number of different types of rolling mill for processing the ingot to its finished shape. These are variously known as Cogging mills, Slabbing mills, Billet mills, Bar mills and Strip mills, which produce plate, sections, bars, sheet and strip. hot rolling is the most commonly used process, durgin which metal is heaten at 1100 1300 °C in order to improve its malleability and workability
0
1
2
3
4
3
Processings cold rolling cold rolling of previously hot rolled strip causes the hardening of the material due to the breaking of the crystalline structure. Higher precision can be reached and better mechanical properties > WIRE DRAWING trafilatura is a metalworking process used to reduce the cross-section of a wire by pulling the wire through a single, or series of, drawing die(s) Drawing is usually performed at room temperature, thus classified a cold working process, but it may be performed at elevated temperatures for large wires to reduce forces
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Processings > EXRTUSION estrusione is a metalworking process similar to wide drawing consisting in pushing the metals through a die of the desired cross-section, after heating the bars at 1100 °C. The cross-sections that can be produced vary from solid round, rectangular, to L shapes, T shapes.
> FORMING stampaggio > BENDING piegatura > FORGING fucinatura
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