Rockwell Hardness Test

The Rockwell hardness test method consists of indenting the test material with a diamond cone or hardened steel ball indenter. The indenter is forced into the test material under a preliminary minor load F0 (Fig. 1A) usually 10 kgf. When equilibrium has been reached, an indicating device, which follows the movements of the indenter and so responds to changes in depth of penetration of the indenter is set to a datum position. While the preliminary minor load is still applied an additional major load is applied with resulting increase in penetration (Fig. 1B). When equilibrium has again been reach, the additional major load is removed but the preliminary minor load is still maintained. Removal of the additional major load allows a partial recovery, so reducing the depth of penetration (Fig. 1C). The permanent increase in depth of penetration, resulting from the application and removal of the additional major load is used to calculate the Rockwell hardness number.

HR = E - e


F0 = preliminary minor load in kgf
F1 = additional major load in kgf
F = total load in kgf
e = permanent increase in depth of penetration due to major load F1 measured in units of 0.002 mm
E = a constant depending on form of indenter: 100 units for diamond indenter, 130 units for steel ball indenter
HR = Rockwell hardness number
D = diameter of steel ball
Rockwell hardness test principle
Larger View

Fig. 1.Rockwell Principle


Rockwell Hardness Scales
ScaleIndenterMinor Load
F0
kgf
Major Load
F1
kgf
Total Load
F
kgf
Value of
E
ADiamond cone105060100
B1/16" steel ball1090100130
CDiamond cone10140150100
DDiamond cone1090100100
E1/8" steel ball1090100130
F1/16" steel ball105060130
G1/16" steel ball10140150130
H1/8" steel ball105060130
K1/8" steel ball10140150130
L1/4" steel ball105060130
M1/4" steel ball1090100130
P1/4" steel ball10140150130
R1/2" steel ball105060130
S1/2" steel ball1090100130
V1/2" steel ball10140150130


Typical Application of Rockwell Hardness Scales

HRA . . . . Cemented carbides, thin steel and shallow case hardened steel
HRB . . . . Copper alloys, soft steels, aluminium alloys, malleable irons, etc.
HRC . . . . Steel, hard cast irons, case hardened steel and other materials harder than 100 HRB
HRD . . . . Thin steel and medium case hardened steel and pearlitic malleable iron
HRE . . . . Cast iron, aluminium and magnesium alloys, bearing metals
HRF . . . . Annealed copper alloys, thin soft sheet metals
HRG . . . . Phosphor bronze, beryllium copper, malleable irons HRH . . . . Aluminium, zinc, lead
HRK . . . . }
HRL . . . . }
HRM . . . .} . . . . Soft bearing metals, plastics and other very soft materials
HRP . . . . }
HRR . . . . }
HRS . . . . }
HRV . . . . }

Advantages of the Rockwell hardness method include the direct Rockwell hardness number readout and rapid testing time. Disadvantages include many arbitrary non-related scales and possible effects from the specimen support anvil (try putting a cigarette paper under a test block and take note of the effect on the hardness reading! Vickers and Brinell methods don't suffer from this effect).





Links To:

Hardness Testing

Rockwell Hardness Test

Rockwell Superficial Hardness Test

Brinell Hardness Test

Vickers Hardness Test

Microhardness Test

Mohs Hardness Test

Scleroscope and other hardness testing methods


Hardness Conversion Tables and Charts:

Hardness Conversion Table(colour version - may take time to load)

Hardness Conversion Table(non-colour version)

Hardness Conversion Chart (1)

Hardness Conversion Chart (2)

Chart of Brinell, Vickers and Ultimate Tensile Strength Equivalents (1)

Chart of Brinell, Vickers andUltimate Tensile Strength Equivalents (2)

Hardness Conversion Table related to Rockwell C Hardness Scale (hard materials) (colour)

Hardness Conversion Table related to Rockwell C Hardness Scale (hard materials) (non-colour)

Hardness Conversion Chart related to Rockwell C Hardness Scales (hard materials)

Estimated Hardness Equivalent Chart related to Rockwell C and Vickers (hard materials)

Hardness Conversion Table related to Rockwell B Hardness Scale (soft metals) (colour)

Hardness Conversion Table related to Rockwell B Hardness Scale (soft metals) (non-colour)

Hardness Conversion Chart related to Rockwell B Hardness Scale (soft metals)

Table of Minimum Test Piece Thickness for Rockwell Hardness Testing using Ball Indenters

Table of Minimum Test Piece Thickness for Rockwell Hardness Testing using Diamond Indenters

HV, MPa and GPa Conversion Calculator

Surface Engineering Forum







Gordon England Independent Thermal Spray Coating Consultant
Telephone: +44 (0)1252 405186

Email: tsc@gordonengland.co.uk

Site Links



Introducing

Nature of Thermal Spray Coatings

Surface Engineering in a Nutshell

Surface Engineering Forum

Thermal Spray Gun Repair Service

Plasma Consumable Parts

Thermal Spray Powder Supplies

Applications:

Thermal Spray Coatings on Carbon and Glass Fibre Reinforced Polymers

HVOF Coating of Paper Making Roll

Abradable Coatings

Photomicrographs

Thermal Spray Processes:

Combustion Wire Thermal Spray Process

Combustion Powder Thermal Spray Process

Arc Wire Thermal Spray Process

Plasma Thermal Spray Process

HVOF Thermal Spray Process

HVAF Thermal Spray Process

Detonation Thermal Spray Process

Plasma Flame Theory

Cold Spray Coating Process



Wear and Use of Thermal Spray Coatings

Corrosion and Use of Thermal Spray Coatings

Glossary of Thermal Spray and Surface Engineering Terms

Image Directory for Thermal Spray Coatings

Plasma Gas Flow Information

Plasma Gas Flow Correction Calculator

Contact Form

Links to other interesting sites related to thermal spray and surface engineering

Reciprocal Links

Periodic Table of the Elements

SI Units

Calculators for Conversion between Units of Measurement

Hardness Testing

Surface Engineering Message Board Archive

Surface Engineering Message Board Archive Index

Photography Gallery

Photography Gallery3


© Copyright Gordon England