This document discusses various mechanical properties of engineering materials including hardness, creep, elasticity, hardening, and plasticity. It defines each property and describes methods for measuring hardness, factors that influence creep, the hardening process, and how plastic deformation occurs at the atomic level resulting in a permanent change in shape even after removal of stress. Measurement techniques for hardness include Rockwell, Brinell, Vickers, Knoop, and shore hardness tests. Creep is influenced by load, temperature, composition, grain size, and heat treatment. Hardening increases hardness through metallurgical processes.

2. CONTENT
 Introduction
 Hardness
 Creep
 Elasticity
 Hardening
 Plasticity
 Reference

3. Introduction
 The substances which are useful in the field of engineering are
called Engineering materials. A particular material is selected is
on the basis of following considerations
 Properties of material
 Mechanical properties - strength, ductility, toughness, hardness,
strength to weight ratio etc.
 Physical properties - density, specific heat, thermal expansion,
conductivity , melting point etc.
 Chemical properties - oxidation , corrosion, flammability,
toxicity etc.
 Manufacturing properties - formed, casting, machined, welding

4. Hardness
 Hardness is the resistance of material to permanent
deformation of the surface.
 Hardness is not a fundamental property of a material,
but a combined effect of compressive, elastic and
plastic properties
 It can be measured by nondestructive testing.

5. Hardness Measurement
 Hardness measurement can be in Macro, Micro &
nano – scale.
 Measurement of the Macro-hardness of materials
is a quick and simple method of obtaining
mechanical property data.
 The Macro-hardness measurement will be highly
variable.
 Micro-hardness measurements are appropriate.

6. Hardness Measurement Methods
 Rockwell hardness test
 Brinell hardness
 Vickers
 Knoop hardness
 shore

7. Hardness Testers

8. Creep
 When materials under severe service conditions are
required to sustain steady loads for long periods of
time, they undergo a time dependent deformation.
 the slow and progressive deformation of a material
with time at constant stress.

9. Factors affecting creep
 Load
 Temperature
 Composition
 Grain size
 Heat treatment

10. Elasticity
 The property of a material to regain its original
configuration after removal of external forces.

11. Elasticity

12. Hardening
 The heat treatment process in which we can improve
the hardness of the material is called hardening.
 Hardening is a metallurgical and metalworking
process used to increase the hardness of a metal.

13. Hardening process

14. Plasticity
 Property of material to be deformed repeatedly
without rupture by the action of a force, and remain
deformed after the force is removed.
 Property of material due to material does to regain its
original configuration that property is termed as
Plasticity

15. Plastic Deformation (Metals)
15
1. Initial 2. Small load 3. Unload
Plastic means permanent.
F

linear
elastic
linear
elastic
plastic

16. Plastic Deformation (permanent)
 From an atomic perspective, plastic deformation
corresponds to the breaking of bonds with original
atom neighbors and then reforming bonds with new
neighbors.
 After removal of the stress, the large number of atoms
that have relocated, do not return to original position.
 Yield strength is a measure of resistance to plastic
deformation.

17. Reference
 O.P. KHANNA , DHANPAT RAI PUBLICATIONS,
2013

18. END