First, the concept of hardness is the ability of materials to resist elastic deformation, plastic deformation or destructive force. For the hardness test conducted by the press-in method, the hardness is the ability of the substance to resist the pressing of another relatively rigid object having a certain shape and size into its surface.
Second, the principle of Rockwell hardness test Rockwell hardness measurement method is to use the specified pressure head, under the application of two test forces (primary test force Fo and total test force F), press into the surface of the sample, in total After the test force is maintained for a certain period of time, the main test force F1 is removed, the initial test force is retained, and the indentation depth h1 is measured, and the difference Δh between the indentation depth h1 and the indentation depth ho under the initial test force indicates Rockwell. The hardness is determined by the axial displacement of the indenter of 0.002 mm as a Rockwell hardness unit, which is generally read directly from the indicator dial. The principle of action is shown in the following figure. The Rockwell hardness value is HR=K- in the following formula: C is usually equal to 0.002 mm K - the constant is 100 when using the diamond cone indenter, and 130 is the Rockwell hardness test principle when using the steel ball indenter. Figure
Third, Rockwell hardness test characteristics The Rockwell hardness test adopts the method of measuring the penetration depth. The hardness value is directly read by the indication, so the operation is simple and convenient, easy to master, and the work efficiency is high, and it is suitable for the inspection of batch parts; Rockwell hardness The test method can be used with diamond indenter and rigid ball indenter. It can measure hard and soft samples and has a wide range of applications. Therefore, the Rockwell hardness test is widely used in production, which is to verify the quality of the product and determine the reasonableness. The main means of testing of the processing technology. Rockwell hardness tester is the most commonly used test instrument for hardness testing and teaching and research work in production enterprises, universities and colleges.