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Hardness
The document provides an overview of material hardness, including its definition, importance, and various testing methods. It details historical techniques for measuring hardness, such as the Mohs, Brinell, Rockwell, Vickers, and Knoop hardness tests, along with typical hardness values for various materials. Additionally, it includes instructions for a lab exercise on conducting a Brinell hardness test.
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Hardness
- 1. Properties of Materials- Hardness By Akhtar Husain 22 Aug 2017
- 2. • Introduction • Definitionand Importance • Why and How to Determine Hardness • History of Hardness Tests • Mhos Scale • Brinell Hardness Test • Rockwell Hardness Test • Vickers Hardness Test • Knoop Hardness Test • Comparison of Different Hardness Scales • Some Typical Hardness Values • Lab Exercise-Brinell Hardness Test Properties of Materials – Hardness Sequence
- 3. Engineering The application ofscience and mathematics by which the properties of matter and the sources of energy in nature are made useful to people. Merriam-Webster Properties of Materials – Hardness Introduction
- 4. Engineering The application ofscience and mathematics by which the properties of matter and the sources of energy in nature are made useful to people. Merriam-Webster Properties of Materials – Hardness Introduction
- 5. Forces on Rigid Bodies External Effects Acceleration, Velocity Impulse, Momentum Internal Effects Stresses Propertiesof Materials – Hardness Introduction
- 6. Forces on Rigid Bodies External Effects Acceleration, Velocity Impulse, Momentum Internal Effects Stresses Propertiesof Materials – Hardness Introduction
- 7. Properties of Materials– Hardness Introduction Stresses Deformations Temporary Permanent
- 8. • Introduction Properties ofMaterials - Hardness Properties Strength Hardness Ductility Toughness Other
- 9. • Introduction Properties ofMaterials - Hardness Properties Strength Hardness Ductility Toughness Many More
- 10. • Definition – Resistanceto plastic deformation, usually by indentation. However, the term may also refer to resistance to scratching, abrasion, or cutting. • Importance – We need to ascertain the hardness for two main reasons:- • To confirm material characteristics • To ensure part functionality Properties of Materials - Hardness
- 11. • Hardness canbe used to estimate tensile strength of most steels. • Hardness value is good indication of effectiveness of heat treatment. • Being a non-destructive test, it can be accomplished on finished parts. • It is relatively simple. Properties of Materials – Hardness Why Check Hardness
- 12. Scientist and engineerswere aware of the importance of hardness for centuries; different techniques were employed to determine hardness. The main techniques have been:- • Performing scratch test • Size of impression produced on the surface by pressing an indenter against it by a known force • Depth of indentation produced on the surface by pressing an indenter against it by a known force Properties of Materials – Hardness How to Determine Hardness
- 13. • 1822: FriedrichMohs (Ger) - A ten-point scratch hardness Mohs scale. • 1900: J. A. Brinell (Swe) - A ball indentation / dent dia size Brinell Hardness. • 1920: S. R. Rockwell (US) – Minor, major load / dent depth Rockwell Hardness. • 1925: R. Smith and G. Sandland (Eng) – Diamond pyramid indenter / dent diagonal size , allows microhardness tests to be carried out, Vickers (Micro) Hardness. • 1939: F. Knoop, C. G. Peters and W. B. E. Emerson (US) - Elongated diamond indenter, allow hardness tests on glass and ceramics also, Knoop Hardness. Properties of Materials – Hardness History of Hardness Tests
- 14. Properties of Materials– Hardness Mhos Scale Principle : By Scratching
- 15. Properties of Materials– Hardness Brinell Hardness Test Where F= Applied Force in kgf D= Indenter Dia in mm Di=Indentation Dia in mm
- 16. Properties of Materials– Hardness Rockwell Test Principle Principle : HR= N- t/s N & s are scale factors t
- 17. Properties of Materials– Hardness Rockwell Test Principle
- 18. Properties of Materials– Hardness Rockwell B Hardness Test • Major Load 100 kg • Minor Load 10 kg
- 19. Properties of Materials– Hardness Rockwell C Hardness Test • Major Load 150 kg • Minor Load 10 kg
- 20. Properties of Materials– Hardness Vickers Hardness Test HV = 1.854(F/D2)
- 21. Properties of Materials– Hardness Knoop Hardness Test HV = 1.854(F/l2)
- 22. Properties of Materials– Hardness Hardness Test Machine
- 23. Properties of Materials– Hardness Comparison of Different Hardness Scales
- 24. Properties of Materials– Hardness Comparison of Different Hardness Scales
- 25. Properties of Materials– Hardness Comparison of Different Hardness Scales Sut = (3.5 BHN) MPa
- 26. Properties of Materials– Hardness Typical Hardness Values Material Hardness Soft wood (e.g. pine) 1.6 HBS 10/100 Hard wood 2.6 to 7.0 HBS 1.6 10/100 Aluminium 15 HB Copper 35 HB Mild steel 120 HB 18-8 (304) stainless steel 250 HB Cold Drawn Steel Glass 325 HB 550 HB Hardened tool steel 650 - 700 HB
- 27. Properties of Materials– Hardness Lab Exercise-Brinell Hardness Test We will measure the hardness of an aluminum plate. The diameter of the spherical indenter in will be 2.5 mm, the imposed load will be 30 kgf, the time of loading will be 30 s. We will measure the indent size with the aid of optical microscope, its division is 1/10 mm.
- 28. Properties of Materials– Hardness Lab Exercise-Brinell Hardness Test Caution : The Hardness test machines can only be operated under the supervision of Lab Engineer 1. Select a location for the test Remove oil or dirt, but the surface does not need to be polished 2. Make sure the part can be held securely. 3. Raise the spherical indenter according to the red mark on the scale. 4. Apply the 30 kgf load and wait 30 seconds 5. Remove the load 6. Measure the indent size with the aid of the optical microscope. 7. Calculate the Brinell hardness with the equation:- 8. Write a short report on the Brinell Hardness Test.
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