Material Testing and Properties

Question 1

compressive strength

Answer 1

ability to withstand crushing forces

Question 2

tensile strength

Answer 2

ability to withstand stretching forces

Question 3

bending strength

Answer 3

ability to withstand bending forces

Question 4

shear strength

Answer 4

ability to withstand sliding forces on a parallel plane to the material

Question 5

torsional strength

Answer 5

ability to withstand twisting forces from applied torque or torsion

Question 6

hardness

Answer 6

ability to withstand abrasion, indentation and cutting

Question 7

toughness

Answer 7

ability to absorb sudden shocks without fracturing

Question 8

plasticity

Answer 8

ability to be permanently deformed and retain the new shape

Question 9

ductility

Answer 9

ability to be drawn into a wire under a tension

Question 10

malleability

Answer 10

ability to withstand deformation and compression without cracking

Question 11

elasticty

Answer 11

ability to be deformed and then return to the original shape when the force is removed

Question 12

density

Answer 12

the mass per unit volume

Question 13

fusibility

Answer 13

how well a material can be converted to a liquid state

Question 14

magnestism

Answer 14

a materials ability to interact with or create a magnetic field

Question 15

corrosion/degradation resistance

Answer 15

ability to withstand an attach from the environment or decay

Question 16

electrical conductivity

Answer 16

how well a current can travel through a material (its resistance)

Question 17

thermal conductivity

Answer 17

how well heat is transferred through a material

Question 18

thermal expansion

Answer 18

how a materials volume increases as it is heated

Question 19

Opaque

Answer 19

a material which blocks all light travelling through it

Question 20

translucent

Answer 20

a material which blocks some of the light travelling through it

Question 21

transparent

Answer 21

a material that allows all light to pass through it

Question 22

workshop test for toughness

Answer 22

lock a test piece in a vice and strike it with a hammer compare if it fractures or deforms. a tougher material will deform and absorb the blow

Question 23

workshop test for hardness

Answer 23

use a hammer and dot punch to indent the material
the harder the material the smaller the diameter of the indentationn

Question 24

workshop test for malleability and ductility

Answer 24

lock a test piece in a vice
bend it through 90 degrees or until it fractures
cracking on the inside of the bend is a lack of malleability
cracking on the outside is a lack of ductility

Question 25

workshop test for corrosion

Answer 25

place test piece in an exposed area or in a corrosive chemical and leave for an extended period
compare the relative break down of each material

Question 26

workshop test for conductivity

Answer 26

use a multimeter and set the probes to either end of the material
test the resistance of the material and compare it to other samples
higher resistance is a lower conductivity

Question 27

workshop test for thermal conductivity

Answer 27

use a bunsen burner to heat one end of a material
set up a thermometer on the other end
time how long it takes for the thermometer to increase in temperature

Question 28

Industrial test for tensile strength

Answer 28

use a tensometer machine
the test piece is gripped at both ends
on clamp is attached to a worm drive which pulls it backwards
the load, extension and breaking point are recorded and plotted on a stress/strain graph

Question 29

industrial test for toughness

Answer 29

Izod impact test
a notched test piece is held vertically in a vice
a pendulum is released from a fixed height and strikes the test piece
the rebound height is recorded
tougher materials will absorb the blow and the rebound height is small
brittle materials do not absorb the blow and the rebound height is larger

Question 30

Industrial test for malleability/ductility

Answer 30

use a bend test
bending machine uses a mandrel or plunger to bend a test piece through a set angle the cracks are observed and compared
cracks on the outside of the bend indicate a lack of ductility
cracks on the inside of the bend indicate a lack of malleability

Question 31

Industrial test for corrosion

Answer 31

very similar to workshop testing but done in a lab environment with far greater control of the conditions of corrosion

Question 32

Industrial test for thermal conductivity

Answer 32

heat flow meter
material is placed between two temperature controlled plates
temperature is increased at a constant rate
thermal sensors on the surface of the material measure the temperature across the material

Question 33

NDT(non-destructive testing )

Answer 33

testing materials without damaging or destroying them
it is used to find defects in materials

Question 34

X-ray NDT

Answer 34

X-ray beam passes through a material and is absorbed different in defects than in the nominal material allowing an imagine to be generated of the tiny imperfections of the material

Question 35

ultrasonic NDT

Answer 35

sound waves are pushed through a material
where they interact with a defect they distort allowing defects to be identified

Question 36

industrial test for hardness (vickers pyramid)

Answer 36

for very hard materials
a diamond pyramid is loaded and indents into a material
a microscope measures the indentation and the extent of indentation determines the hardness of the material
the diamond is used as it will not deform

Question 37

Industrial test for hardness (Rockwell)

Answer 37

a diamond indenter is preloaded to break through the surface of a material
additional load is applied over a dwell time
the distance between the indentation of the preload and the applied load is measured

Question 38

Industrial test for hardness (Brinell)

Answer 38

a hardened steel ball is forced into a material the diameter of the indent is recorded and compared
a wider indent is a less hard material