Steel Material

Question 1

What are some pros of steel as a building material? (4)

Answer 1

• Homogeneous properties
• Light in proportion to its strength
• Well-suited for rapid construction
• Plentiful and relatively inexpensive

Question 2

What are some cons of steel as a building material? (2)

Answer 2

• prone to corrosion

- loss of strength in fires

Question 3

What is steel?

Answer 3

steel is basically an alloy of iron and carbon, but several other elements are used in various proportions and combinations to give steel different properties

Question 4

What two groups do ferrous alloys come in?

Answer 4

• steel

- cast iron

Question 5

What are the three main types of steel?

Answer 5

• low carbon steel
• medium carbon steel
• high carbon steel

Question 6

What are the characteristics of low carbon, or mild steel? (3)

Answer 6

• soft, good ductility and weldability
• employed in cold-rolled or hot-rolled condition
• used for pressed work and where welding is required

Question 7

What are the characteristics of medium carbon steel? (3)

Answer 7

• high strength
• ductility or toughness may be obtained by heat treatment
• used mostly in machinery components

Question 8

What are the characteristics of high carbon steel? (3)

Answer 8

• very high strength and hardness
• used in heat-treated conditions
• used mainly for tools and dies

Question 9

How does carbon content affect iron alloys?

Answer 9

greater proportions of carbon generally increase the hardness and decrease the ductility of the iron alloy

Question 10

Describe the microstructure of A36 steel grade. (2)

Answer 10

• ferrite grains

- pearlite grains

Question 11

Describe the microstructure of a pearlite grain. (2)

Answer 11

• ferrite layer (light gray)

- iron carbide layer (dark gray)

Question 12

How is iron found in its natural state?

Answer 12

not as a pure metallic material, but as a mineral in the form of iron oxides

Question 13

How much iron does the mined material contain?

Answer 13

between 20% and 60%

Question 14

What is ore containing more than 60% iron called, and why?

Answer 14

reduced ore, since it does not require additional refining

Question 15

What are the three basic raw materials needed in the production of iron?

Answer 15

• iron ore
• coal
• limestone

Question 16

How is coal used in iron production?

Answer 16

coal is converted into coke and used as burning fuel for the blast furnace

Question 17

How is limestone used in iron production?

Answer 17

limestone is used as a flux material in the blast furnace

Question 18

What do coal, limestone, and iron ore work together to produce?

Answer 18

pig iron, the basic material used in the production of all ferrous metals and alloys

Question 19

What is pig iron?

Answer 19

a metallic iron material containing a small percentage of carbon and traces of silica, manganese and phosphorus

Question 20

How is carbon content reduced in a basic-oxygen furnace?

Answer 20

by blowing oxygen through molten carbon-rich pig iron, producing an alloy with desired chemistry for low-carbon steel

Question 21

What may be added to a basic-oxygen furnace?

Answer 21

a carefully controlled amount of scrap steel

Question 22

How does an electric arc furnace work?

Answer 22

scrap metal and/or direct reduced ore, pig ore, molten blast furnace steel are heated by means of an electrical arc current to desired melting point

Question 23

What are the advantages of an electric arc furnace? (3)

Answer 23

• may use scrap metal only
• reduced energy requirement in comparison to other furnaces
• may be stopped and restarted easily, giving flexibility of production for various grades of material

Question 24

What is the disadvantage of an electric arc furnace?

Answer 24

must be near abundant electrical grid

Question 25

What is the next step in iron production after blasting?

Answer 25

molten steel is then transported to be poured into molds or cast into slabs, blooms, or billets

Question 26

What is the next step in iron production after molding/casting?

Answer 26

these are then transported to be cooled slowly till room temperature is achieved prior to rolling in desired shape and size

Question 27

How is hot-rolled steel made?

Answer 27

billets or blooms are heated above recrystallization point and then rolled into desired shape and length

Question 28

How is hot-rolled steel cooled?

Answer 28

after, they are slowly cooled to room temperature

Question 29

What are wide-flanged shaped (W-shapes) used for?

Answer 29

the most commonly used shape for beams and columns

Question 30

What are channels, angles and tees used for?

Answer 30

trusses, lighter-weight framing, and other miscellaneous uses

Question 31

What size are angle shapes?

Answer 31

4"x3" nominal legs with 3/8" thickness

Question 32

What are WT shapes?

Answer 32

T-shape cut from a W-shape

Question 33

What shapes do hollow structural sections (HSS) come in?

Answer 33

hollow square, rectangular, round, and elliptical shapes

Question 34

How are HSS made?

Answer 34

made by cold or hot-forming steel strip and welding longitudinally

Question 35

What are HSS resistant to?

Answer 35

especially suitable for structural members subject to twisting or buckling stresses

Question 36

What are HSS used for?

Answer 36

trusses, structurally efficient column sections, and where the simple external profile is desirable

Question 37

What does strengthening steel improve?

Answer 37

strength, ductility and durability

Question 38

What are the three methods used to alter steel's microstructure?

Answer 38

- heat treatment: formation of additional grain boundaries - strain or work-hardening: generation of dislocations - alloying: introduction of interstitial and/or substitutional atoms

Question 39

How is steel weathering prevented?

Answer 39

surface oxidation adheres to base metal, limiting further rusting

Question 40

Where is weathering steel used?

Answer 40

highway and bridge structures, eliminating the need for a protective coating

Question 41

How is stainless steel made?

Answer 41

added nickel and chromium

Question 42

What is the purpose of stainless steel?

Answer 42

forms self-protecting oxide layer that provides long-lasting protection against corrosion

Question 43

What is a downside of stainless steel?

Answer 43

much more expensive

Question 44

What products are made from cold-formed steel? (3)

Answer 44

- corrugated steel decking - light-gauge metal studs and joists - high-strength wire for concrete prestressing strands

Question 45

What is cold-working?

Answer 45

working or shaping at near-ambient temperatures

Question 46

How is cold-working unique?

Answer 46

plastic flow of the material increases the number of dislocations which pile/tangle up on intersecting slip planes

Question 47

What is the advantage of cold-working?

Answer 47

the increase in deformation during the fabrication processes results in an increased resistance to further deformation while in service

Question 48

What is the disadvantage of cold-working?

Answer 48

increases strength, but decreases toughness