1. METALS Composition and Microstructure Ferrous Metals and Alloys
Non-Ferrous Metals and Alloys
Specifications and Proof Testing
Corrosion

2. Composition and Microstructure
Metal: element that readily loses electrons to form positive ions, characterized by high electrical conductivity and malleable
Alloy: combinations of metals in a crystalline structure

3. Structure of Metals
Microstructural properties determine all of the material properties of metals and alloys.
Different from Covalent and Ionic Bonds

4. Alloying Structure 3-D lattice in metalic bonds provides
opportunity for other element to occupy some of the positions.
or for small element to enter the lattice

5. Interstitial Alloy Between atomic lattice location
< 60% of the size of the lattice atoms
only a small % can fit interstitially
For Transition metals only a few fit
H, B, C, N

6. Substitutional Alloy Replacing elements in the lattice
+ 15% radius of lattice atoms
large percentage is possible
Alloys may contain both interstitial and substitutional elements

7. Forming a Crystalline Structure
Liquid: large degree of disorder
Freezing Point: order begins to form
Grain Initiation: initiation energy
Solidification: ordered lattice structures form
Grain Boundary: separate lattices collide
FCC:BCC or FCC:FCC with different angle

8. Forming a Crystalline Structure
Grain Structure: each grain has its own lattice structure (FCC, BCC, HCP).

9. Introduction to Steel Production Commercial Forms Applications
Microstructure
Strengthening Mechanisms
Corrosion

10. Metal Processing Crushing and Calcining, or Separation Extraction
Smelting
Ore is melted and separated in solution
Electrolytic processing
electric furnace or process is used to separate metal
Leaching (liquid processing)
metal is recovered from leachate

11. Ferrous Metals
principle element is iron, cast iron, steel, wrought iron.
Metals come from ore, "minerals" ore consists of metal and gangue (valueless extra)
Mining
open pit
underground

12. Refining the Metal Refining the Metal oxidizing impurities
distillation
chemical agents
electrolysis

13. Iron Production Blast Furnace Molten Iron Slag
Reduces iron ore to metal
Separates metal from impurities
Molten Iron
Slag

14. Processing of Virgin Steel
1) first step in reducing iron ore,
2) separates impurities
3) absorbs carbon (leaves % carbon)
End product is cast in bars, "pigs".

15. Ferrous Metals Pig Iron
Iron ore is combined with coke, and limestone (fluxing agent). Blasts of hot air are forced through the material to ignite the coke and melt the iron ore. The impurities in the iron are absorbed by the limestone and forms blast furnace slag.

16. Forms of Ferrous Alloys
Cast Iron
cast iron is pig iron is any other shape. Remelted and cast into desired shape.
Malleable Cast Iron
annealed (heating then slow cooling to encourage refined grains and soften mechanical properties, removes internal stresses, removes gases) cast iron that has been made more ductile and formable.

17. Forms of Ferrous Alloys
Wrought Iron
a form of iron that contains slag, and virtually no carbon. making it workable when it is hot but hardens very rapidly when cooled rapidly.
Ingot Iron
low carbon steel or iron cast from a molten state.

18. Forms of Ferrous Alloys
Steel
Iron - Carbon alloy which is cast from a molten mass in a form which is malleable. Carbon steel is steel with less than 1.5% carbon. Alloy steel is steel which has properties controlled by elements other than carbon.
Steel has the best structural properties of these materials

19. Carbon Steels
Carbon steels have between .008 and 1.7 percent C (most are between 0.1 and 0.8%)
Carbon may be substitutional or interstitial depending upon the amount present
Alloys with greater than 1.7 percent carbon become very brittle and hard, i.e. cast iron properties.

20. Phase Diagrams Phase Diagrams relate the Inverse Lever Law
composition & temperature
to the
crystalline structure (“phase”)
Inverse Lever Law
determines the percentage of each crystalline phase

21. Melting Temperature of B
Two Component (Binary) Phase Diagram for completely soluble elements or compounds
Melting
Temperature of A
Liquid
Temperature, °C
Liquid +
Solid a
Look at the melting temperature for each element
Alloying element A with element B drops the melting temperature
Solid a
Components
Melting Temperature of B
Percent A by weight 10 20 30 40 50 60 70 80 90
100
Percent B by weight
100 90 80 70 60 50 40 30 20 10

22. Two Component (Binary) Phase Diagram: Ni - Cu
1700
1000
1100
1200
Nickel - Copper Alloy
1600
Liquid
Liquidus Line
1500
1455°C
1400
Temperature, °C
1300
Liquid +
Solid a
Cu and Ni are completely soluble because the electronegativities, radii, crystal structure (FCC), etc. are the similar.
Solidus Line
Solid a
1084°C
Percent Ni by weight 10 20 30 40 50 60 70 80 90
100
Percent Cu by weight
100 90 80 70 60 50 40 30 20 10

23. Binary Phase Diagram for insoluble elements or compounds
Liquid A + B
Temperature. °C
Liquid + A
Liquid + B
Solid A + B
Composition of A
Composition of B
Actual atomic form will depend
on the composition of formation
(will discuss later for steel)

24. Definitions Eutectic Reaction – Eutectic Point – Eutectic Solid –
Eutectics are often lamellar

25. Water - NaCl Phase Diagram15 10 5
Liquid – Brine (Water + Dissolved NaCl) -5
Temperature. °C
Eutectic Point
-10
Salt +
-15
Ice + Brine
Brine
Recall that pure water freezes at 0 C or 32 F. By using salt, the freezing point is depressed. Sodium chloride depresses the freezing point. In addition, when NaCl goes into solution, it is an exothermic reaction, which means that it liberates heat.
Calcium Chloride and Magnesium chloride in about 32 percent solution both have much lower freezing points (-60 F), but are much more expensive and unnecessary for most conditions.
Brine can promote corrosion of unprotected reinforcing steel in concrete
-20
-25
Ice + Salt
-30 5 10 15 20 25 30
-21 oC (-5.8°F)
Weight Percent NaCl
23.3%

26. Binary Phase Diagram for partially soluble elements or compounds
Temperature. °C
Liquid
Solid a + b
Eutectic Point
Composition of A
Composition of B b a
a + Liquid
b + Liquid

27. Lead-Tin Phase Diagram
61.9%
19.2%
97.5%
183°C
327°C
232°C
Liquid
Liquid + a a
Liquid +b
a + b b

28. Definitions
Eutectoid Reaction –
Eutectoid Point –
Eutectoid –

29. Steps to Analyzing a Phase Diagram
Determine the phase/phases present at the point (composition vs. temperature)
The mass percentage composition of each phase at the point can be determined by the drawing a horizontal through the point for the length of the entire region.
The intersection of the horizontal line and a line on the phase diagram defines the composition of the solution.

30. A Point with 2 Phases
If the point is located in a region with more 2 phases, the mass percentage of each phase within the region can be determined by the inverse lever law.

31. Inverse Lever Law
Inverse Lever Law (Derivation on pgs of text)
The mass percentage of a phase present in a two phase region is the length along the “tie line” portion from the state point to the other phase region divided by the total “tie line” length. Compositions are used as a measure of length.
State Point x y
Mass percentage of Phase I
in the two-phase region:
y/(x+y)
Mass percentage of Phase II
In the two-phase region:
x/(x+y)
Phase I Region
(e.g. Solid)
Phase II Region
(e.g. Liquid)
Phase I + Phase II Region
(e.g. Solid + Liquid)

32. Example: Ni-Cu
For a 1000 kg block of Ni-Cu metal at a defined state point of 53% Nickel and 47% Copper at 1300 oC, determine the following:
Compositions (%) of both the liquid and solid phases
Mass percentages of the liquid and solid phases
The mass of Nickel in the Liquid Phase

33. Example: Ni - Cu Nickel - Copper Alloy Liquid Liquid + Solid a
1700
1000
1100
1200
Nickel - Copper Alloy
1600
Liquid
Liquid +
Solid a
1500
State Point 53% Ni, 47 % Cu
1400
Temperature, °C
1300
Solid a
Percent Ni by weight 10 20 30 40 50 60 70 80 90
100
Percent Cu by weight
100 90 80 70 60 50 40 30 20 10

34. Phase diagram for Fe-C Cementite: Ferrite: above 4.35 to 6.67
very hard and brittle alloy forms
6.67% Carbon % Iron "iron carbide"
Ferrite:
iron which contains very little carbon. this is soft ductile material

35. Phase diagram for Fe-C Pearlite: Austinite:
combination of ferrite and cementite structures
intermediate property structure
Austinite:
solid state gamma phase iron-carbon combination.

36. Phase Diagram for C-Fe

37. Microstructure Phases of Steel Grain Size Ferrite (BCC)
Austenite (FCC)
Cementite (Orthorhombic)
Delta Iron (BCC)
Grain Size

39. Time-Temperature-Transition Curves
Critical Temp.
Coarse Pearlite
Fine Pearlite
Bainite
Martinsite

40. Heat Treatments Annealing Quenching
heated above critical temperature and
cooled slowly
softens structure
Quenching
cooled rapidly in water or oil
improves hardness and strength

41. Heat Treatments Tempering heated below critical temperature, held and
quenched
improves ductility and toughness
while retaining hardness

44. Mild Steel Grades A992 “Low Alloy” Carbon Steel
Common Structural Sections
Replaced A36 steel
A 572 “High-Strength Low-Alloy Columbium-Vanadium Steel”
Grades 42, 50, 60, 65
Structural sections and bolts.....

45. Mild Steel Grades A 615 Billet Reinforcing Steel A588 Weathering Steel
low alloy, high ductility steel
reinforcing bars
A588 Weathering Steel
should not be used in Cl water environments
Free from moisture 40% of the time; avoid extreme humid environments

46. Corrosion Oxidation of metal requires oxygen, water,
two different metals connected electrically
electrolyte

47. Corrosion Major problem with steel Control Methods Protective Coatings
Galvanic Protection
Cathodic Protection
Corrosion-resistant Steels

48. S-N Curve

49. Strengthening Mechanisms
Alloying
Heat Treating
Cold Working

50. Alloying Forming Solid Solution with Iron Formation of Carbide
Carbon, Chromium, Manganese, Nickel, Copper, and Silicon
Formation of Carbide
Titanium, Vanadium, and Molybdenum
Formation of an Undissolved, second phase
Lead, Sulfur, and Phosphorus

51. Heat Treatments
Full Annealing
Process Annealing
Normalizing
Quenching

52. Cold Working Plastic deformation
Done below recrystallization temperature

53. Other Properties of Steel
Impact
resistance to dynamic loadings (toughness)
Creep
time dependent deformation due to sustained loads
Ductility
mild steels may yield at  = and
fracture at  > 0.200

54. Forms of Steel Structural Shapes Reinforcing Steel
Wide flange sections,
Channels,
Tubing,
Plate
Reinforcing Steel
Cold Rolled forms, pans, sheet
Pipe

55. Structural Grades ASTM AISI - SAE A36 & A 572 (being phased out)
A992 Structural Shapes
A325 Bolts
AISI - SAE
10XX
XX defines Carbon content
13XX
13 defines a manganese alloy steel

56. Applications Structural Members Bolts, Connectors Reinforcement Tools
Machines

57. Steel Grades