Introduction to metal hardness and Vickers hardness measurement

There are many hardness systems for metal hardness, commonly used brinell HB, Rockwell HR, Vickers HV, these three hardness methods are static measurement methods, which are applied to different materials and applications. The desktop hardness tester designed and manufactured according to the definition of hardness has the advantages of accurate measurement and independent of the elastic modulus of materials. But there are also large volume, heavy weight, long test time, can not be measured on site, can not measure the problem of large workpiece. The indentation of Brinell hardness tester and Rockwell hardness tester is larger, and the damage to the workpiece is larger. The use of optical vickers hardness measurement, high requirements for operators.

To solve these problems of static hardness system, there are two kinds of portable dynamic hardness system commonly used. They are Lee's and Shaw's hardness tester. Dynamic method of the two hardness tester has the advantages of small volume, light weight, easy to carry. However, with the advantage of portability, the measured value is related to the elastic modulus of the material to be measured, so it is necessary to use a conversion table to convert the hardness to the commonly used Brinell hardness. Both the elastic modulus and the conversion table will bring errors.

Vickers hardness "refers to the use of a relative Angle of 136 degrees between diamond is pyramid head, within the prescribed load F down into the surface of tested samples, keep on time after the loading, unloading d measuring indentation diagonal length, and then calculate the indentation surface area S, and finally the average pressure of indentation on the surface area, is the metal vickers hardness value of HV said with symbol. HV = 0.102 * F/S. In the actual measurement, there is no need to calculate, but according to the measured D value, directly look up the table to get the measured hardness value.

The diagonal length D is generally measured using a microscope, so it has high requirements for operators. Long measurement time. Table vickers hardness tester is large in volume and heavy in weight. Not suitable for field measurement and large workpiece measurement.