This part deals with the meaning of hardnbess. The importance of hardness and how to measure comparative values. Aportable apparatus can be used connected with a lap top or with any feasible means of recording the results can be appled. The mechanical properties, i.e., yield strength of the material can be obtainedusing this NDT test without destructing the component by simply multiplying the reco9rded hardness reading by a constant depending on the carbon equivalent of the material.

1. PART II
HARDNESS

2. Objectives
• To measure the hardness of the materials by Rockwell, Brinell and
Vickers hardness test.
• To become familiar with Combined Digital Hardness Tester.
2
HARDNESS

3. Introduction
• Hardness is the resistance of metal to plastic
deformation, usually by indentation.
• The term may also refer to stiffness or temper, or to
resistance to scratching, abrasion, or cutting.
• It is the property of a metal, which gives it the ability
to resist being permanently, deformed (bent,
broken, or have its shape changed), when a load is
applied.
• The greater the hardness of the metal, the greater
resistance it has to deformation.
3

4. Hardness Test Advantages
• They are simple and inexpensive—ordinarily no special
specimen need be prepared, and the testing apparatus is
relatively inexpensive.
• The test is nondestructive—the specimen is neither
fractured nor excessively deformed; a small indentation
is the only deformation.
• Other mechanical properties often may be estimated
from hardness data, such as tensile strength
4

5. Hardness Measurement Methods
• Brinell hardness test.
• Rockwell hardness test.
• Vickers hardness test.
• The three methods determine the metal's resistance to the
penetration of a non-deformable ball , cone and pyramid.
• The tests determine the depth which such a ball or cone will
sink into the metal, under a given load, within a specific
period of time.
5

6. Hardness: Measurement
6

7. Rockwell Hardness Test
• The indenter may either be a steel ball of some specified diameter or
a spherical diamond-tipped cone of 120° angle.
• A minor load of 10 kg is first applied, which causes an initial
penetration and holds the indenter in place.
• Then, the major load is applied (60,100,150) for HRA, HRB and
HRC respectively .
• Upon removal of the major load, the depth reading is taken while
the minor load is still on. The minor load of 10 kg is NOT taken into
account in the computation.
• Then, the hardness number can be read directly from the scale.
7

8. ROCKWELL STANDARDS TESTS
Hardness Scale Rockwell A Rockwell B Rockwell C
Total load in Kg
(pre-load 10Kgf)
60 100 150
Actual weight
Applied marked as
1 60kg
1 60kg
2 40kg
1 60kg
2 40kg
3 50kg
Indenter Diamond cone 120 0 Steel Ball
1/16 dia
Diamond cone 120 0
Material
Measurement
8

9. Brinell Hardness Test
• Brinell hardness is determined by forcing a hard steel or carbide
sphere of a specified diameter (2.5mm) under a specified load into
the surface of a material and measuring the diameter of the
indentation left after the test.
• The Brinell number, is obtained by dividing the load used, in
kilograms, by the actual surface area of the indentation, in square
millimeters.
• After the impression is made, a measurement of the diameter of the
resulting round impression is taken.
• The hardness is calculated by dividing the load by the area of the
curved surface of the indention, (the area of a hemispherical surface
is arrived at by multiplying the square of the diameter by 3.14159
and then dividing by 2).
9

10. Brinell Hardness Test Cont.
Where:
BHN = Brinell Hardness Number
F = the imposed load in kg
D = the diameter of the spherical indenter in mm
Di = diameter of the resulting indenter impression in mm
10

11. Vickers Hardness Test
• It is the standard method for measuring the hardness of metals, particularly
those with extremely hard surfaces: the surface is subjected to a standard
pressure for a standard length of time by means of a pyramid-shaped
diamond.
• Vickers hardness is a measure of the hardness of a material, calculated from
the size of an impression produced under load by a pyramid-shaped
diamond indenter.
• The indenter employed in the Vickers test is a square-based pyramid whose
opposite sides meet at the apex at an angle of 136º.
• The Vickers number (HV) is calculated using the following formula:
HV = 1.854(F/D^2)
F : the applied load (measured in kilograms-force)
D : arithmetic mean of the length of the two diagonals of the indentation, in
mm
11

12. Brinell and Vickers Standards
VICKERS 30
HV30
Rockwell b
BRINELL
HB 2.5/187.5
Total Load in kg
30
(pre-load 3kgf)
100 kg
(pre-load 10kgf)
187.5
(pre-load 10kgf)
Actual weight
Applied marked as
30kg
1 60kg
2 40kg
1 60kg
2 40kg
3 50kg
4 37.5kg
Indentor
Diamond Pyramid
1360
Steel ball 1/16 in Steel Ball
2.5 mm dia
Material
Measurement
12

13. Results
• RHN(A,C) =100-500t
• RHN(B) = 130-500t
Where t is the depth of the indentation in mm.
You are responsible for calculating the depth as was shown in the
lectures.
• For Vickers and brinell hardness tests check previous slides
13

14. Why Check Hardness?
Hardness Testing
Presented by Willrich Precision
Ph 866-945-5742 / sales@Willrich.com
Created by Walter Wardzala, Major Instrument Sales Specialist

15. Why Check Hardness?
Hardness Testing
Presented by Willrich Precision
Materials Testing
Tensile
Charpy Impact
Fatigue
Ductility
Corrosion Testing
Structure
Hardness

16. •Stiffness — resists deformation
•Toughness — resists failure, even after deforming
•Strength — resists both deformation and failure
•Ductility — deforms before it breaks
•Brittleness — breaks before it deforms
•Hardness — resists dents, scratches, and other permanent
changes under compressive force
•(Malleability-Elasticity-Plasticity…)
6 Properties of Materials

17. Indentation Hardness Testing
Resistance to penetration
Brinell
Vickers
Rockwell (Superficial-Microficial)
Scratch Test
Durometers
Leeb (Impact)
Birkovich

18. NOT a fundamental property of material
i.e like Tensile Strength or Density
Rockwell is a unit less value (like percentage)
Vickers Load over Area / Pascals/ mPA-Gpa
Resistance to Penetration

21. Brinell
The First Widely Accepted Hardness
Test
1897
10mm Ball
500-3000 kgf
Low Power Scope

22. Brinell- The First Widely Accepted Hardness Test

23. Macro Vickers
Rockwell-like construction
1 kgf. and over
Common Euro and Japanese test
Best surface not required

24. Micro Vickers
Less than 1 kgf.
20-100 micron d typical

25. Case / Gradient Hardness
Most common type application

26. Vickers/ Knoop
All testers come with Vickers indenters
A Knoop indenter may replace it or HM200
machines can add a second indenter assembly

27. HM210 Micro Vickers
New HM210
Closed loop force control
Motorized turret
Up to 4 lenses (Retrofitable)
Up to 2 Indenters
10-1000 gf. Adjustable
LED Illumination
Note: No vise/fixturing is included.

28. HM/HV Automation

29. HM 210/220 Type A Tester
Uses a digital filar eyepiece where the operator manually
determines the end points of the indentation.
A CCTV can be added for easier viewing.

30. AVPak-10 Software (Type B-C-D Testers)

31. Why Rockwell?
World Wide Standards
ASTM E18
Very Common Test
Fast cycle time
The Scale defines all!
Minimum Thickness Charts
√ The Prints!

32. Yellow indicates scales that can be performed with included indenters
ASTM E18 Key Points
Timing! Test on one side of block only!
Spacing of 3 diameters between indents, 1 HR value is 80 millionths travel

33. Yellow indicates scales that can be performed with included indenters

34. • 1 Load
• 2 Displacement
• 3 Indenter
• 4 TIMING!
3 Components of
Rockwell Testing

35. Anvils and Accessories

36. Data Collection/SPC Options

37. USB Input Tool Direct
Data Collection from a hardness tester direct to Excel
06ADV380E Fits most hardness testers

38. Rockwell Pocket Guide

39. Rockwell Pocket Guide

40. Some 21st Century catastrophies

41. ASTM
• The American Society for Testing and Materials formed
in 1898 (2001) by a chemist for the Pennsylvania
Railroad
• Voluntary Consensus Society

42. Portable Hardness Testers
• Proprietary Scales
• Different Forces
• Different Indenters
• Material Dependent
• Operator Dependent

43. RELATIO9NSHIP BETWEEN HARDNESS NUMBER AND TENSILE
MECHANICAL PROPERTY OF METALS
The yield strength in tension is about 1/3 of the hardness.
.
For example: HV 300 corresponds to a Sigma-y of approximately 1000 MPa. An
approximate relationship between the hardness and the tensile strength (of steel) is,

44. END OF PART II
TO BE FOLLOWED
BY PART III