Metals

Question 1

Why alloy a metal

Answer 1

Improve strength, corrosion resistance, wear resistance but also lead to reduction n ductility and toughness and ability to wield metal.

Question 2

Alloy

Answer 2

Mixture of metal with one or more other metallic element or non metal

Question 3

Component

Answer 3

An element included in an alloy

Question 4

Phase

Answer 4

A regional of material having uniform physical and chemical characteristics

Question 5

Composition

Answer 5

The mass of each component present in an alloy or phase

Question 6

What’s a complete solid solution

Answer 6

Single phase region in which solute atoms have mixed with solvent atoms to form a homogeneous composition. Solite atoms are completely soluble in solvent atoms for any composition of solute and solvent.

Question 7

Cooling curve for a composition

Question 8

Label an equilibrium phase diagram for limited solid solubility.

Question 9

What is the structure at the just alpha or beta point in equilibrium diagram

Answer 9

Solid rich in one element, where the other is the solute component in an FCC structure.

Question 10

Why does liquidus line a decreasing slope

Answer 10

Additional of one element decreased melting point

Question 11

What is the invariant point

Answer 11

Point E on equilibrium diagram. Where liquidus lines meet

Question 12

Lever rule

Answer 12

1. The tie line is constructed across the two-phase region at the temperature of the alloy
2. The overall alloy composition is located on the tie line
3. The fraction of one phase is computed by taking the length of tie line from the overall alloy
   composition to the phase boundary for the other phase, and dividing by the total tie line
   length
4. The fraction of the other phase is determined in the same manner
5. If phase percentages are desired, each phase fraction is multiplied by 100. When the
   composition axis is scaled in weight percent, the phase fractions computed using the lever
   rule are mass fractions—the mass (or weight) of a specific phase divided by the total alloy
   mass (or weight). The mass of each phase is computed from the product of each phase
   fraction and the total alloy mass

Question 14

Ferrous alloys

Answer 14

Iron containing

Question 15

Carbon content in steel

Answer 15

0.04-1.7%

Question 16

Carbon content in cast iron

Answer 16

More than 1.7%

Question 17

Low alloy steel

Answer 17

When carbon is the only significant alloy

Question 18

Alloy steel

Answer 18

When other alloying elements significantly present

Question 19

Low carbon steel

Answer 19

0.04-0.3% carbon

Question 20

Medium carbon steel

Answer 20

0.3-0.7%

Question 21

High carbon

Answer 21

0.7-1.7%

Question 22

Why is greater than 4% carbon steel not used for engineering

Answer 22

Too brittle

Question 23

What other alloys are in stainless steel

Answer 23

Cr and Ni

Question 24

Other alloys in grey cast iron

Answer 24

Silicone, magnesium and cerium

Question 26

What are the different forms of pure iron

Answer 26

Ferrite- BCC crystal structure. Magnetic. Exists at temps bellow 910 degrees. Soft and ductile compared to cementite Austenite- FCC crystal structure. Non magnetic. Temp range 910 to 1391 δ-Fe - BCC crystal structure. Temp range 1391 to 1536

Question 27

Cementile

Answer 27

6.7 % carbon fixed conetent. Hard and brittle. Fe3C

Question 28

Eutectic point

Answer 28

A liquid is in equilibrium with two solid phases (mixture of two or more substances melt)

Question 29

Eutectoid point

Answer 29

A solid is in equilibrium with two other solid phases

Question 30

Pearlite

Answer 30

Eutectoid structure. An equilibrium structure of alternating ferrite and cementite layers or lamellar. Formed when cooled an alloy of Eutectoid composition from γ phase under equilibrium conditions. Pearlite form by the simultaneous precipitation of α and Fe3C at the eutectoid temperature. It is not a single phase.

Question 31

Hyper Eutectoid

Answer 31

Alloy containing less than the Eutectoid composition of carbon

Question 32

Hyper-Eutectoid

Answer 32

Alloy with carbon composition more than Eutectoid composition

Question 33

When does transformation of γ to pearlite take place

Answer 33

Always at Eutectoid temperature

Question 34

What is the difference of cooling a hypo-Eutectoid to an hyper-Eutectoid alloy

Answer 34

Hypo forms a microstructure of Pearlite and ferrite. Hyper forms microstructure of cementite and Pearlite.

Question 35

Proeutictoid ferrite

Answer 35

Ferrite formed prior to Eutectoid reaction when hypo Eutectoid γ passes through the two phase field (α+γ)

Question 36

Pro Eutectoid cementite

Answer 36

Cementite formed prior to Eutectoid reaction when hyper-eutectoid γ passes through the two phase field (γ+Fe3C)

Question 37

How to enchante stainless steel corrosion resistance

Answer 37

Nickel or molybdenum additions