When the tested sample is too small or the Brinell hardness (HB) is greater than 450, Rockwell hardness (HR) testing is used instead
Degree measurement. The test method is to use a diamond cone with a vertex angle of 120 degrees or a steel ball with a diameter of 1.59mm/3.18mm, and press it into the surface of the tested material under a certain load. The hardness of the material is determined by the indentation depth.
According to the different hardness of experimental materials, they can be divided into three different scales to represent:
HRA uses a hardness of 60kg load and diamond cone pressing into the surface of the material, suitable for materials with extremely high hardness. For example: hard alloy.
HRB is the hardness obtained using a 100kg load and a 1.58mm diameter quenched steel ball, used for materials with lower hardness For example: annealed steel, cast iron, etc
HRC uses a 150kg load and a diamond cone to press the hardness onto the surface of the material, and is used for materials with high hardness. For example: quenched steel, etc
There are three different standards for Rockwell hardness: HRA, HRB, and A, B, and C in HRC. It is called ruler A, ruler B, ruler C. The Rockwell hardness test is one of several commonly used indentation hardness tests today. The initial pressure of the three scales is 98.07N (10Kgf), and the hardness value is calculated based on the indentation depth. The ruler A uses a ball cone diamond shaped indenter and then applies pressure to 588.4N (60Kgf); Scale B uses a steel ball with a diameter of 1.588mm (1/16 inch) as the indenter, and then applies pressure to 1471N (150Kgf), making it suitable for detecting softer materials. Scale C is suitable for detecting harder materials.
Application of Rockwell Hardness
The HRA ruler is mainly used to measure the Rockwell hardness of very hard materials, such as hard alloys, very thin and hard steels, and hardened materials with very thin surface hardening layers;
The HRC scale is the most widely used Rockwell hardness scale. Mainly used for measuring materials such as general steel, castings with high hardness, pearlite malleable iron, and quenched and tempered alloy steel.
The HRB ruler is also widely used. Commonly used for measuring low hardness materials such as low-carbon steel, soft metals, copper alloys, aluminum alloys, and malleable iron.
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Material : Steel
DIY Supplies : Metalworking