Hardness Testing

Question 1

What is hardness testing used for?

Answer 1

Hardness testing is used to calculate the hardness levels of materials and products.

Question 2

What are some properties of hard materials? (name 2)

Answer 2

Hardness is important in many applications.

Hard materials are resistant to deformation, wear and scratching of the surface.

Question 3

Explain the principle of operation for hardness testing (2 points of info)

Answer 3

Principle of operation:

1. An indent is made in the surface of the material with a specifically shaped indenter.
2. The hardness is calculated based on the size of the indentation and the force used.

Question 4

Name four applications of hardness testing

Answer 4

Applications:

1. Test the wear-resistance of products.
2. Test the hardness of cutting tools.
3. Check the results of heat treatment.
4. Quality control in manufacturing plants.

Question 5

Name the three types of hardness testing.

Answer 5

Brinell, Vickers, Rockwell

Question 6

What type of indenter does the Brinell hardness test use and what material is it made of?

Answer 6

It uses a ball indenter made of tungsten (carbide) or hardened steel.

Question 7

What type of indenter does the Vickers test use? What angle must it be?

Answer 7

It uses a square pyramid indenter with a point angle of 136 degrees.

Question 8

What measurements and calculations are made during the Brinell hardness test?

Answer 8

Method of Measurements:

Using the diameter of the indent and the force used, a hardness value is calculated

Question 9

What measurements and calculations are made during the Vickers hardness test?

Answer 9

Method of Measurements:
Using the diagonal distance for vickers (or the diameter for rockwell cone) and the force used, a hardness value is calculated

Question 10

Explain the application suitability of the Brinell Hardness Test.

Answer 10

Not suitable for very hard or very soft materials.
Cannot be used for thin materials.
Ball may deform on very hard materials.

Question 11

Explain the application suitability of the Vickers Hardness Test.

Answer 11

Suitable for very hard materials (e.g. hardened steel, titanium).
Leaves small indent

Question 12

Describe the vickers hardness test and the steps taken to test a material using this method. (7)

Answer 12

1. Shown above is the Vickers hardness test.
2. A diamond, 136°square based pyramid indenter is used.
3. It is pressed down slowly into the test material with a measured force.
4. The deeper the indent, the softer the material.
5. The diagonals of the indent are used in the calculation to find its hardness value.
6. The diagonals are measured using a microscope.
7. Vickers advantage is it can be used on very hard materials

Question 13

What is the basis for results for both the Brinell and Vickers Hardness Tests?

Answer 13

Basis for results –
The indenter is pushed slowly with a known force into the test piece.
The diameter or diagonal measurement of the indent is read with a microscope with a built-in measuring device.
This is used to find the materials hardness value.