Regarding the hardness of the material

This post was last edited by jyszyx on 2009-6-1 at 12:21. Brinell hardness is a standard for indicating the hardness of materials, first proposed by the Swede Brinell. This method involves applying pressure using a hardened steel ball (HBS) or a cemented carbide ball (HBW), which is pressed into the surface of the material under test to create a dent. The hardness is determined by the pressure per unit area of this spherical dent; HB = F/S, where MPa is the unit (F is in Newtons and S is in square millimeters). It is used to determine the hardness of plastics, rubbers, metal materials, etc. In Rockwell hardness, the A, B, and C in HRA, HRB, HRC, etc., represent three different standards, known as Scale A, Scale B, and Scale C. The Rockwell hardness test is one of the several common indentation hardness tests in use today; the initial pressure for all three scales is 98.07 N (equivalent to 10 kgf), and the hardness value is then calculated based on the depth of the indentation. Scale A uses a spherical-cone rhombus indenter, and the pressure is applied to 588.4 N (equivalent to 60 kgf) ； Scale B uses a steel ball with a diameter of 1.588 mm (1/16 inch) as the indenter, and a pressure of 980.7 N (equivalent to 100 kgf) is applied ； Scale C uses the same ball-cone rhombus as scale A as the indenter, but the force applied is 1471 N (equivalent to 150 kgf). Therefore, scale B is suitable for relatively soft materials, while scale C is suitable for harder materials. HR = K – h/0.002 (where h is the residual depth of the indentation, and K is a constant). Both Vickers hardness and Brinell hardness are calculated based on the load per unit area; the difference is that Vickers hardness uses a diamond indenter in the form of a regular tetrahedron with an angle of 136 degrees between its faces. Shore hardness is used to determine the relative hardness of soft materials such as plastics or rubbers. It measures the penetration depth of a specified indenter under defined pressure and time conditions. The hardness value is used to identify or specify plastics with particular hardness levels, and it can also be employed for quality control of multiple batches of material. Test method: Place the specimen on a hard, flat surface. Press the indenter of the hardness tester into the specimen, ensuring that it remains parallel to the surface. Read the values every second (or as determined by the tester). Specimen specifications: Typically, the thickness of the specimen is 6.4 mm (0.25 inches). Several specimens can be stacked to achieve this thickness, but it is preferable to use a single specimen. Test data: The hardness value is read from the hardness tester. Common types of hardness testers are Type A and Type D; Type A is used for softer materials ； Type D is used for harder materials.

For the conversion of hardness values for rigid materials, refer to GB1172 or the first volume of the Mechanical Design Handbook. :)