Types and applications of materials

Question 1

Metal alloys are grouped into two classes, which are … and …

Answer 1

Ferrous alloys, and non ferrous alloys

Question 2

Alloys in which iron is the principle consituent (steels and cast irons).

Answer 2

Ferrous alloys

Question 3

… are produced in larger quantities than any other metal alloy.

Answer 3

Ferrous alloys

Question 4

What are the advantages of ferrous alloys?

Answer 4

• Offer a wide range of mechanical and physical properties.
• Economical production techniques.
• Abundant quantities within the earth’s crust.

Question 5

… are metal alloys that are not iron based.

Answer 5

Non-ferrous alloys

Question 6

… are iron–carbon alloys that may contain appreciable concentrations of other alloying elements.

Answer 6

Steels

Question 7

The mechanical properties of steel are sensitive to the content of carbon, which is normally less than …

Answer 7

1.0 wt%.

Question 8

Some of the more common steels are classified

according to carbon concentration into … , … , …

Answer 8

low-carbon medium-carbon, and

high-carbon types

Question 9

Subclasses exist within each group of steels according to the …

Answer 9

concentration of other alloying elements.

Question 10

What type of steel is produced in the greatest quantities?

Answer 10

low-carbon

Question 11

How much carbon do low-carbon steels have?

Answer 11

less than about 0.25 wt% C

Question 12

… are relatively soft and weak but have outstanding ductility and toughness; in addition, they are machinable, weldable, and, of all steels, are
the least expensive to produce.

Answer 12

low-carbon steels

Question 13

What are typical applications of low carbon steels?

Answer 13

automobile body components, structural shapes, and sheets that are used in pipelines,buildings, bridges, and tin cans.

Question 14

For low-carbon steels what is the yield strength? tensile strengths? and ductility ?

Answer 14

Yield strength: 275 MPa
Tensile strengths: between 415 and 550 MPa
Ductility: 25% EL

Question 15

Another group of low-carbon alloys are the high-strength, low-alloy (HSLA) steels. What other alloying elements do they contain and in what concentrations? Compare their strength in relation to plain low-carbon steels.

Answer 15

copper, vanadium,nickel, and molybdenum in combined concentrations as high as 10 wt%, and
they possess higher strengths than the plain low-carbon steels.

Question 16

high-strength, low-alloy (HSLA) steels may be strengthened by …

Answer 16

heat treatment,

Question 17

What are other properties of high-strength, low-alloy steels?

Answer 17

ductile, formable, and machinable.

Question 18

HSLA steels are more resistant to … than

the plain carbon steels,

Answer 18

corrosion

Question 19

Medium-carbon steels have carbon concentrations between about… .
These alloys may be … to improve their mechanical properties.

Answer 19

0.25 and 0.60 wt%,

heat-treated

Question 20

Heat-treated medium-carbon steels are stronger than the low-carbon steels, but at a sacrifice of …

Answer 20

ductility and toughness

Question 21

Additions of … improve the capacity of medium-carbon alloys to be heat-treated, giving rise to a variety of strength–ductility combinations.

Answer 21

chromium, nickel, and molybdenum

Question 22

Applications of which type of carbon steel include railway wheels and tracks, gears, crankshafts, and other machine parts and high-strength structural components calling for a combination of high strength, wear resistance, and toughness.

Answer 22

Medium-carbon

Question 23

The high-carbon steels, normally having carbon contents between …, are the … , … , and yet least … of the carbon steels.

Answer 23

0.60 and 1.4 wt%

hardest, strongest, ductile

Question 24

What type of carbon steel is wear resistant and capable of holding a sharp cutting edge.

Answer 24

high-carbon

Question 25

high-carbon alloys contain alloying elements ... | which when combine with carbon form very hard and wear-resistant carbide compounds.

Answer 25

chromium, vanadium, tungsten, and molybdenum.

Question 26

... steels are used as cutting tools and dies for forming and shaping materials, as well as in knives, razors, hacksaw blades, springs, and high strength wire.

Answer 26

High-carbon

Question 27

... are highly resistant to corrosion especially the ambient atmosphere.

Answer 27

The stainless steels

Question 28

The predominant alloying element for stainless steel is ...; a concentration of at least ... is required. Corrosion resistance may also be enhanced by ... and ... additions.

Answer 28

chromium, 11 wt% Cr nickel, molybdenum

Question 29

... are frequently used at elevated temperatures and in severe environments because they resist oxidation and maintain their mechanical integrity under such conditions; the upper temperature limit in oxidizing atmospheres is about 1000°C.

Answer 29

stainless steels

Question 30

Applications of ... include gas turbines, high-temperature steam boilers, heat-treating furnaces, aircraft, missiles, and nuclear power-generating units.

Answer 30

stainless steels

Question 31

Cast irons are ferrous alloys with more than ... wt% C | more commonly ...wt% C

Answer 31

2.1, | 3 - 4.5

Question 32

What are properties of cast irons?

Answer 32

Low melting temperature, relatively easy to cast. Generally brittle, thus casting is the most convenient fabrication method.

Question 33

... iron is a type of cast iron, it is - graphite flakes - weak & brittle in tension - stronger in compression - excellent vibrational dampening - wear resistant

Answer 33

Gray iron

Question 34

``` What is this type of cast iron? -add Mg and/or Ce (cerium) - graphite as nodules not flakes - matrix often pearlite - stronger but less ductile ```

Answer 34

Ductile iron

Question 35

what type of cast iron? - Low silicon - < 1 wt% Si - very hard and brittle

Answer 35

White iron

Question 36

what type of cast iron? - heat treat white iron at 800-900ºC - graphite in rosettes - reasonably strong and ductile

Answer 36

Malleable iron

Question 37

What type of cast iron? - relatively high thermal conductivity - good resistance to thermal shock - lower oxidation at elevated temperatures

Answer 37

Compacted graphite iron

Question 38

What are limitations of ferrous alloys?

Answer 38

high densities, low electrical conductivity, poor corrosion resistance.

Question 39

... are characterized by a relatively low density (2.7 g/cm3 as compared to 7.9 g/cm3 for steel), high electrical and thermal conductivities, and a resistance to corrosion in some common environments, including the ambient atmosphere.

Answer 39

Aluminium and alloys

Question 40

Aluminum has an FCC crystal structure, its ... is retained even at very low temperatures.

Answer 40

ductility

Question 41

What is a limitation of Aluminium?

Answer 41

low melting temperature (660°C)

Question 42

The mechanical ... of aluminum may be enhanced by cold work and by alloying; however, both processes tend to decrease resistance to corrosion.

Answer 42

strength

Question 43

Principal alloying elements with Aluminium include ...

Answer 43

copper, magnesium, silicon, manganese, and | zinc.

Question 44

Applications of ceramics include ...

Answer 44

die blanks, cutting tools, sensors

Question 45

What are refractories?

Answer 45

Materials to be used at high temperatures