How to Correctly Apply the Leeb Hardness Test Technology?

The Leeb hardness testing technology is a new technology developed in the world following the cloth, Rock, Vi, and Shore hardness. The Leeb hardness tester manufactured according to the Leeb hardness theory has changed the traditional hardness testing method.

Because the hardness sensor is as small as a pen, it can directly test the hardness of the workpiece in various directions on the production site by holding the sensor, so it is difficult for other desktop hardness testers.

Since the birth of the Leeb hardness tester, it has become more and more popular internationally. In China, the Leeb hardness testing technology has been initially developed. In order to promote this advanced technology, with reference to international standards, the Ministry of Machinery Industry has promulgated "Technical Conditions for Leeb Hardness Tester ZBN7l010-90", and the State Bureau of Quality and Technical Supervision has promulgated " Metal Leeb hardness test method GB/T17394-1998".

Ⅰ. The characteristics of the Leeb hardness tester

1. Both Shore and Leeb hardness are dynamic load test methods, but Shore examines the vertical height of the rebound of the impact body, so it is determined that the shore digital hardness testers should be used vertically downwards, which is bound to cause great limitations in practical use.

The Leeb hardness is different. The Leeb hardness tester examines the speed of rebound and impact of the impact body. Through the speed correction, it can be used in any direction, which greatly facilitates the user.

2. The commonly used cloth, Rock and Vickers hardness testers are inconvenient to use on site due to their large size, especially when testing large and heavy workpieces.

Since the durometer table cannot accommodate it, it cannot be detected at all. The Leeb hardness tester does not need a workbench, and its hardness sensor is as small as a pen, which can be directly operated by hand. It can easily detect whether it is a large, medium-sized workpiece or a workpiece with complex geometric dimensions.

Ⅱ. Factors related to the Leeb hardness test

Since the digital hardness tester machine method is a dynamic load test method, the Leeb hardness value must be related to the elastic modulus E of the metal material, and the elastic modulus corresponding to different materials is also different. Therefore, the Leeb hardness tester is classified and tested according to the type of material.

Ⅲ. Classification and comparison of Leeb hardness test and other hardnesses and testing requirements

From the perspective of microscopic deformation, the cloth, Rock and Vickers hardness examines the plastic deformation of the material, which is expressed as the size or depth of the indentation; the Li and Shore hardness examines the elastic deformation of the material, which is expressed as the magnitude or height of the rebound velocity.

Ⅳ. The requirements of the Leeb hardness tester for measurement

1. Requirements for the surface of the sample

The test surface should have metallic luster, and there should be no oxide scale and other dirt.

2. Sample weight requirements

The specimen must be of sufficient mass and rigidity to ensure that the hardness checking instruments does not shift or bounce during reconstruction.

3. Sample thickness requirements

The sample should be of sufficient thickness, and the sample should not be magnetic.

4. The sample has a surface hardened layer. For the sample with a curved surface, an appropriate support ring should be used to ensure that the position deviation of the impact head at the moment of impact is within 0.5mm.

5. The distance between each measurement point should be greater than 3~4mm, and the test cannot be repeated at the same point, otherwise it will cause a large error in the digital leeb hardness tester. At the same time, the service life of the sensor will be shortened.

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