Chapter 4 material testing

CHAPTER 4 : MATERIAL TESTING

INTRODUCTION

•Many parts are formed into various shape by applying external forces to the workpiece.

•Material Testing is a test done to determine the properties of a substance in comparison with a standard or specification.

PURPOSE

•To determine quality of material•To determine mechanical properties such

as strength, hardness, ductility, toughness, etc.

•To trace defects/ flaws in the materials.•To evaluate materials potential in certain

use.

MECHANICAL PROPERTIES

STRENGTH HARDNESS ELASTICITY

PLASTICITY DUCTILITY TOUGHNESS

BRITTLENESS

Ductility

Plasticity

Toughness

Brittleness

Hardness

Strength

Elasticity

The strength of the material and of its resistance to scratching and to wear.

The ability of a material to have plastic deformation after applying a tensile

load before fracture.Tendency of a material to fracture or

fail upon the application of force, impact, or shock.

The ability of a material to return to its original shape after load is removed.

The ability of a material to withstand tensile force without fractured.

The ability of a material to withstand impact force without fractured.

The ability of a material to deformed permanently and will not return to its

original shape after the load is removed.

DEFINITION

DESTRUCTIVE TEST

DEFINITION

•Tests are carried out to the specimen's failure, in order to understand a specimen's structural performance or material behaviour under different loads.

TYPES OF DESTRUCTIVE TEST

Destructive Test

Hardness Test Toughness Test

Izod TestCharpy

TestBrinell Test

Vickers Test

Brinell Test

Shore Test

BRINELL TEST

•Test procedure : Giving a force to a steel ball against a test surface.

•Principe to measure hardness by Brinell test;i) Thickness of the specimen should be at least 7 times the depth of penetration of the indenter.ii) The location of penetration of the indenter should be at least 3 diameters of the indenter from the edge of the specimen.iii) The test should not exceed 500HB due to the indenter can undergoes elastic deformation.

D = steel ball diameter (mm)d = indent diameter (mm)P/F = force (kg)

VICKERS TEST

•Test procedure : Indenting the test surface with a pyramid diamond indenter.

d1

d2

HV = 1.8544 F

d2

d = d1 + d2 2

ROCKWELL TEST

•Test procedure : Press indenter onto the material surface, first with a minor load and then with major load. i) A minor load is applied and a zero reference position is established ii) The major load is applied for a specified time period.iii) The major load is released leaving the minor load applied.

E = a constant depending on form of indentere = increase in depth of penetration (mm)

HR = ( E – e )

SHORE TEST

•Test procedure : Drop a diamond tipped hammer onto the specimen from a certain height.

•The hardness is related to the rebound of the indenter ( the higher the rebound, the harder the material).