The key difference between HRC and HRB is that the HRC hardness scale uses a spheroconical diamond as its indenter, whereas the HRB hardness scale uses a 1/16-inch ball as the indenter.
HRC and HRB are hardness scales that are derived from the Rockwell hardness scale depending on the indenter that is used for the measurement.
CONTENTS
1. Overview and Key Difference
2. What is Rockwell Hardness Scale
3. What is HRC
4. What is HRB
5. Similarities – HRC and HRB
6. HRC vs HRB in Tabular Form
7. Summary – HRC vs HRB
What is Rockwell Hardness Scale?
Rockwell hardness scale is a scale we can use to determine hardness depending on the indentation hardness of a substance. Rockwell test measures the depth of penetration of an indenter in the presence of a large load in comparison to the penetration by a preload. Moreover, there are different scales using different loads or indenters that we can denote by a single letter. These scales are typically known as HRA, HRB, HRC, etc. The last letter of each of these terms refers to the respective Rockwell scale. The “HR” in these terms refers to “Rockwell Hardness.” The most common scales among them are the HRC and HRB scales.
Figure 01: A Rockwell Hardness Tester
We can give the Rockwell hardness in an equation as follows:
HR = N – hd
Where HR refers to the Rockwell hardness, N and h are scale factors that depend on the scale of the test we are using (e.g. HRC or HRB), and d is the depth in millimetres. The depth is calculated from the zero load point.
What is HRC?
HRC is a hardness scale derived from the Rockwell hardness scale, and its indenter is a “spheroconical diamond.” The major load regarding this hardness scale is 150 kgf. This scale is useful in measuring the hardness of materials such as steel, hard cast iron, pearlitic malleable iron, titanium, deep case-hardened steel, and other materials that are harder than 100 HRB. The N and h factors for this hardness scale are 100 and 500, respectively. HRB scale gives a dimensionless number as the value.
What is HRB?
HRB is a hardness scale derived from the Rockwell hardness scale, and its indenter is a 1/16 inch ball. The major load regarding this hardness scale is 100 kgf. This scale is useful in measuring the hardness of materials such as copper alloys, soft steels, aluminum alloys, and malleable iron. Moreover, the N and h factors for this hardness scale are 130 and 500, respectively. This scale gives a dimensionless number as the value.
What are the Similarities Between HRC and HRB?
- HRC and HRB are hardness scales derived from the Rockwell hardness scale.
- They use indenters for measurement.
- Both have the same h scale factor of 500.
- They give dimensionless numbers as the value.
What is the Difference Between HRC and HRB?
HRC and HRB are hardness scales that are derived from the Rockwell hardness scale depending on the indenter that is used for the measurement. The key difference between HRC and HRB is that the HRC hardness scale uses a spheroconical diamond as its indenter, whereas the HRB hardness scale uses a 1/16 inch ball as the indenter. Moreover, the major load of HRC is 150 kgf, while the major load of HRB is 100 kgf.
Furthermore, HRC is used for measuring the hardness of materials such as steel, hard cast iron, pearlitic malleable iron, titanium, deep case-hardened steel, and other materials that are harder than 100 HRB. HRB, on the other hand, is used for measuring the hardness of materials such as copper alloys, soft steels, aluminum alloys, and malleable iron.
The below infographic presents the differences between HRC and HRB in tabular form for side by side comparison.
Summary – HRC vs HRB
HRC and HRB are hardness scales derived from the Rockwell hardness scale. The key difference between HRC and HRB is that the HRC hardness scale uses a spheroconical diamond as its indenter, whereas the HRB hardness scale uses a 1/16 inch ball as the indenter.
Reference:
1. “Rockwell Scale.” Wikipedia, Wikimedia Foundation, 4 Oct. 2021.
Image Courtesy:
1. “Rockwell hardness tester 001” By Three-quarter-ten – Own work (CC BY-SA 3.0) via Commons Wikimedia