Composition of Metals

1. GROUP 4
Erika Jean Z. Chavez
Renelyn Joyce Guevarra
Jhon Albie Nepomuceno

2. TOPICS TO BE DISCUSSED
Mechanical
Properties of
Metals
Application &
Processing
Alloys
01 02

3. MECHANICAL
PROPERTIES OF
METALS

4. TYPES OF MECHANICAL PROPERTIES
 Defined as those properties which completely
define its behavior under action of external load or
forces.
 Those properties which associated with :
- Its ability to resist failure
- Its behavior under action of external forces
 Knowledge of mechanical properties :
- Essential for engineers in selecting suitable
materials for various applications.

5. MECHANICAL PROPERTIES
 STRENGTH - Ability to withstand or support
external forces or load without rupture.
 HARDNESS - Ability to resist deformation by
abrasion, indentation or penetration and
scratching by harder bodies.
 DUCTILITY - Ability to undergo appreciable
plastic deformation before rupture.
 BRITTLENESS - Ability to fracture when
deformed . Opposite to ductility

6.  TOUGHNESS - Ability to absorb maximum
energy up to fracture. Must be strong & ductile to
be tough. Shows ability to withstand impact.
Value increase when temperature increases.
 ELASTICITY - Ability to retain its original shape
& size after removal of load.
 PLASTICITY - Ability to experience permanent
deformation without fracture when subjected to
external forces.

7.  RESILIENCE - Ability to absorb energy when it
is elastically deformed.
 MALLEABILITY - Ability to be deformed into
thin sheets by rolling or hammering without
fracture
 MACHINABILITY - Ability to be cut or removed
by cutting tools in various ,machining operations.

8.  WELDABILITY - Ability of 2 similar or
dissimilar metals to be joined by fusion& with or
without filler.
 CASTABILITY - Ability to be formed into
different shapes & sizes from its liquid state.

9. MECHANICAL TEST OF METALS
 All mechanical properties of metal- established by
conducting tests on various testing machines.
 Types of mechanical test :
- Tensile test - Creep test
- Hardness test
- Impact test
- Compressive test
- Fatigue test

10. TENSILE TEST
 Tensile test understand mechanical
behavior by stress-strain test.
 3 ways of load application –tension,
shear, compression
 Most common mechanical stress-
strain performed in tension

11.  Performed to determined ;
- Elastic limit
- Yield point
- Ultimate tensile strength
- % of elongation & reduction
of area

12. STANDARD TENSILE
SPECIMEN
 Circular cross section
 Reduced section diameter = 12.8
mm
 Reduce section length = 60mm
 Gauge length = 50mm

13. STANDARD TENSILE SPECIMEN
 Procedure :
 Specimen held in holding grips of
apparatus
 Load applied gradually at a constant
rate
 Specimen will be elongated until
fracture

14. DATA RECORDED – LOAD vs.
ELONGATION :
 Normalized to engineering stress &
engineering strain.
ENGINEERING STRESS :

15. ENGINEERING STRAIN :
PLOT A GRAPH – STRESS vs. STRAIN :
 OA is a straight line
 Stress & strain proportional (Hooke’s Law)
 where E = modulus of elasticity
 Slope corresponds to E

16. ENGINEERING STRESS vs. STRAIN :
Engineering stress is the applied
load divided by the original cross-
sectional area of a material. Also
known as nominal stress.
Engineering strain is the amount
that a material deforms per unit
length in a tensile test.

17. PLOT A GRAPH – STRESS vs. STRAIN :
 Called elastic deformation
 When applied load is released, specimen returns
to its original shape.
AB IS A SMALL CURVE :
 A is a point where elastic deformation end and
plastic deformation begin.
- Phenomenon of yielding occurs.
- Called proportional limit.
- Initial departure from linearity

18. AB IS A SMALL CURVE :
 To determine yielding point precisely.
- Construct straight line parallel to elastic portion
of σ-∊ curve at a specified strain offset (0.002)
- B is the intersection of parallel line with curve
- The stress defined as a yield strength, σy
σ-∊ behavior for some steels :
 Elastic-plastic transition
- well defined
- occurs abruptly

19.  Yield point phenomenon
- Upper yield point – plastic deformation
initiated. σ decrease.
- Lower yield point – deformation fluctuated at
constant σ
- Yield strength σy , average σ of lower yield
point
BC IS AN UPWARD CURVE
 Stress increase to maximum limit (point C)
 Called tensile strength , TS

20.  Corresponds to maximum σ that can be
sustained by a structure in tension .
 Necking begin to form- decrease of cross-
sectional area
CD IS A DOWNWARD CURVE
 Specimen continues to elongate
 Requires lesser load to continue
deformation. σ decrease.
 D is a point of fracture or rupture

21. TRUE STRESS :
TRUE STRAIN :

22. TRUE STRESS vs. STRAIN :
True stress is determined by
dividing the tensile load by the
instantaneous area.
True strain is the natural
logarithm of the ratio of the
instantaneous gauge length to the
original gauge length.

23. DUCTILITY
 Measure degree of plastic
deformation that has been
sustained at fracture
 Can be expressed as :
- % elongation
- % area reduction

24. % elongation (% E)
% area reduction (%AR)

25. BRITTLE MATERIAL
 Has little or no plastic
deformation upon fracture
 Has less than 5% elongation

26. HARDNESS TEST
 Hardness test
 Measure hardness by forcing an
indenter into materials surface.
 Indenter – made of harder material
– usually in form of ball.
pyramid or cone

27. HARDNESS TEST
 Early Hardness Test
- Done by comparing with 10
standard mineral
- Increasing hardness on Moh’s scale
1. talc 6. orthoclase
2. Gypsum 7. quartz

28. 3. Calcite 8. topaz
4. Fluorite 9. corundum
5. Apatite 10. diamond
IMPORTANT TEST
 Brinell Hardness Test
 Rockwell Hardness Test
 Viekers Hardness Test
 Knoop Hardness Test

29. BRINELL HARDNESS TEST
 By Dr Johan August Brinell in
1900
 Performed by pressing steel ball
into surface of test pieces using
appropriate force.

30.  Formula :
- Brinell Hardness Number ,
HB (or BHN)

31. ROCKWELL HARDNESS TEST
 Devised in the USA
 The most common method:
 Simple to perform
 Require no special skills
 Quick & direct reading

32.  Performed when hardness is beyond
range of Brinell’s
 load is smaller than Brinell’s
VIEKERS HARDNESS TEST
 The most accurate test
- Has continuous scale of hardness (10
to 1000)
 Indenter

33. - Diamond square based pyramid
with 136ᵒ angle between opposite faces.
 Load
- Smaller than Rockwell & Brinell
- Between 1 and 1000 g
 Suitable for:
- Small, thin selected specimen
region

35. KNOOP HARDNESS TEST
 Very much similar to Vickers
 Indenter :
- Diamond pyramid with short depth and
diagonal in ratio in ratio of 7:1
 Measure diagonal length under
microscope.
 Knoop hardness number designated by HK

37.  Hardness scale for Knoop & Vickers
- Approximately equivalent
 Both are referred as micro hardness testing
- Basis of reload & indenter size
 Suitable for testing
- Brittle materials (ceramics)
- Extremely thin metal
- Exceptionally hard, very shallow
carburized or nitride surface

38. IMPACT TEST
 Many machine parts are subjected to
sudden applied loads – impact loads
 Important engineering wise to have :
- Material that can withstand impact
load without fracturing

39.  A hard, strong may not be suitable
when subjected to sharp sudden load.
 Capacity of metals to withstands impact
without fracture
- Impact resistance or impact strength
- Indication of toughness

40.  Method of measuring toughness
- Impact- testing apparatus
 Types of impact-testing apparatus
- Charpy
- Izod

41. IMPACT TEST

42. TEST

43. APPLICATION &
PROCESSING
ALLOYS

46. Example : Damascus Steel
 Produced from high carbon
(hypereutectic) steel -1.5% C bloom, or
cake (wootz – produced in India exported
to Damascus)
 Characteristic surface pattern
(damascene) produced by microstructure
bands of Fe3C

47. – Band formations favored by some
carbide forming elements, e.g, V, Mn, Cr,
Nb, Mo
– Vanadium and other carbide-
forming impurities
existed in iron ores from South India

63. THANK
YOU!