Hardness Testing Flashcards
What is hardness?
A measurement of resistance to surface indentation
Why is hardness testing used?
1) Grading similar material
2) Quality control
3) Determining mechanical properties like tensile strength
4) Selection of materials for specific applications
Steels with carbon contents of up to 2% are typically
________ and _________.
harder, stronger
What has the biggest impact on material hardness?
1) Carbon
2) Heat treatment
3) Cold working
What is the definition of Brinell Hardness?
The load in kg divided over the surface area of indentation in mm^2
What does “W” in HBW denote?
HBW tells the user that the Hardness test used was Brinell. The “W” Denotes that a tungsten carbide ball was used.
What are the 3 load selections used in Brinell hardness testing and what are their applications?
1) 3000 kg, used for hard materials with sufficient thickness
2) 1500 kg, used for materials with intermediate hardness
3) 500 kg, used for soft materials
How long is the load applied for in Brinell hardness testing?
15-30 seconds
What are Rockwell hardness numbers related to?
Depth of the penetration between major and minor load
What are the major and minor loads of the HRB scale?
Minor load = 10 kg
Major load = 100 kg
Used for mild steels, Cu-Alloys, Al-Alloys
What are the major and minor loads of the HRB scale?
Minor load = 10 kg
Major load = 100 kg
Used for Steels, Hard cast alloys, and Ti-Alloys
What are the advantages of the Brinell Hardness test?
1) Less surface preparation
2) Available in a portable version
3) Fewer tests are required due to the large surface area giving a bulk reading
4) Uses a single scale
What are the limitations of the Brinell Hardness test?
1) Not recommended for brittle materials
2) Leaves a large indent
3) Human error involved in reading indent diameter
4) Not recommended for thinner samples
What are the advantages of the Rockwell Hardness test?
1) Less human error as optical reading is not required
2) Fast and simple
3) Higher versatility due to a number of scales available
What are the limitations of the Rockwell Hardness test?
1) Requires 3 test points to get an average due to a small indent size
2) Requires more surface preparation
3) Proper load and indenters have to be used
