Methods for investigating and testing materials

Question 1

Why is material testing used?

Answer 1

To help select the most suitable material for a product/application

Question 2

How do we make material tests fair?

Answer 2

• use same size material for each test
• make sure environmental conditions are the same
• use same technique and testing equipment
• use ome person to take all measurements

Question 3

What are simple workshop tests?

Answer 3

They use basic tools and equipment

Question 4

How can we tell is a material has more sensible strength?

Answer 4

Less deflection under load means more tensile strength

Question 5

What is a toughness test?

Answer 5

Tough materials absorb impact, brittle materials bend or shatter

Question 6

What is a hardness test?

Answer 6

Material is tested using a dot punch and the force from a Hammer

Question 7

How can we tell the hardness of a material?

Answer 7

The smaller the indent from the dot punch, the harder the material

Question 8

What is a malleability and ductility test?

Answer 8

When the test piece is bent to 90 degrees

Question 9

What indicates a lack of ductility?

Answer 9

Cracks on the outside indicate a lack of ductility

Question 10

What indicates a lack of malleability?

Answer 10

Cracks on the inside indicate a lack of malleability

Question 11

What is Corrosion testing?

Answer 11

Place equally sized materials outside in an area exposed to effects of weather and leave for a period of time. Materials can be visually inspected for surface corrosion

Question 12

What is an electrical conductivity test?

Answer 12

Collect samples of same dimensions and mark a set distance to place multimeter probes. Measure resistance on multimeter. The higher the resistance, the lower the conductivity

Question 13

What is the thermal conductivity test?

Answer 13

• collect material samples of the same dimension
• measure a set distance from one end of material and place a thermometer there
• light a bunsen burner under the other end of the material
• record time it takes for the temperature to reach set point on material
• the shorter the time it takes, the higher the thermal conductivity of the material

Question 14

What are industrial test?

Answer 14

They are usually carried out in a lab with specific testing machinery, using standardised test pieces of material

Question 15

What is the machine used to measure tensile strength?

Answer 15

A tensometer machine tests for tensile strength

Question 16

How do you perform a tensile strength test in industry?

Answer 16

• the standard test piece is held in a clamp at each end
• one clamp is fixed and other moves on a worm drive gear mechanism,putting the material under tension
• test piece is stretched, load and distance is plotted

Question 17

What does the load and distance travelled give us information on? (Tensile strength)

Answer 17

• elastic limit
• yield point
• maximum load
• final breaking point after ‘necking’

Question 18

What I’d the test for toughness in industry?

Answer 18

The izod impact test is used to test toughness

Question 19

How do you perform a test for toughness in industry?

Answer 19

• a notched test piece is held virtually in the vice of the machine
• a pendulum is released from a set position and swings to strike the test piece
• the energy absorbed by the test piece is calculated from the height the pendulum swings to after it hits the test piece
• the material that absorbs the most impact is the toughest
• brittle materials absorb less energy less energy and the pendulum swings further

Question 20

What is the test for hardness?

Answer 20

The rockwell, brunelleschi and vickers pyramid tests

Question 21

What is the rockwell test?

Answer 21

Preload applied to material sample using a diamond indented which breaks through the surface of the material
- diamond will not deform under load
- preloaded is the datum or zero reference point
- an addition load is then applied to test material and held for a predetermined length of time
- load is released and distance between preloaded and applied load is measured

Question 22

What is the brinell test?

Answer 22

• a hardened standard size steel ball is forced into the material’s surface using a pre-set load
• the diameter of the indent in the surface is measured

Question 23

What is the vickers pyramid test?

Answer 23

• used for very hard materials
• uses a diamond square-based pyramid to indent the surface of the material
• a microscope is used to measure the size of the indent

Question 24

What is NDT?

Answer 24

Non-destructive testing

Question 25

What is NDT carried out on?

Answer 25

Carried out on products rather than materials

Question 26

What is NDT used for?

Answer 26

Used to find defects in the material without breaking it

Question 27

What are the two NDT method?

Answer 27

• ultrasonic
• x-ray

Question 28

How to NDT test with ultrasonic?

Answer 28

Sound waves are pulsed into the material, different sounds indicate faults

Question 29

How to NDT test with x-rays?

Answer 29

X-ray beam is passed through a material and image is projected onto a display which allows you to observe tiny details

Question 30

How to test for malleability and ductility industrially?

Answer 30

Tested using a bend test

Question 32

How do you carry out a bend test?

Answer 32

• test piece is placed into a bending machine and held
• a mandrel or plunger loss test piece and bends it to a predetermined angle untol piece fractures
• crack on outer bend indicate level of ductility
• cracks on inside of the bend indicate level of malleability

Question 33

What is Corrosion testing in industry?

Answer 33

Similar to how it is testing for in a workshop except environmental effects are simulated in a lab.

Question 34

What does a bend test test for?

Answer 34

Tests how well a material withstands cracking during one continuous bend

Question 35

What is the test for electrical conductivity in industry?

Answer 35

It is the same as the test in a workshop except carried out on a larger scale

Question 36

What is the test for thermal conductivity?

Answer 36

It is the same as in a workshop except everything is controlled using sensors and machinery