Comparison Between Leeb Hardness Tester And Ultrasonic Hardness Tester

- Jan 15, 2019-

Product name Leeb hardness tester Ultrasonic hardness tester Quality of the sample The higher the sample quality, the more reliable the hardness value of the Leeb hardness tester. The minimum quality requirement is 3KG for high hardness samples and 1.5KG for low hardness samples. If the sample does not meet the requirements, the inertia of the sample should be improved by coupling or compression support. The effective collision quality should be estimated for the non-compact sample, and the centroid and yaw angle should be calculated. If it is not handled properly, it will cause a large error. It can measure products with a total thickness of 2mm or more, a plating layer of 20um or more, and a weight of 100g or more. Surface roughness of the sample The process of impacting the impactor on the surface of the sample is divided into two parts: the finishing stage and the impact indentation stage. The larger the surface roughness, the greater the kinetic energy of the impact body consumed during the finishing stage. The measured value is lower than the actual value, which has a great influence on the high hardness sample. High hardness samples are required, Ra≤2um (▽6 or more), and low hardness samples Ra≤8um (▽4 or more). The greater the surface roughness, the greater the binding force of the surface to the resonant rod indenter, the higher the resonant rod frequency, causing the measured value to be lower, which has a greater influence on the low hardness specimen, but Ra≤12.5um (▽3 or more) Has little effect. A sample with a relatively large roughness requires an ultrasonic probe with a large test force to measure. Thickness test of the thickness of the test piece The thickness requirement of the test part in the test direction is not only to prevent the puncture, but also to prevent the support due to the shape, without the support or the support method is different, so that the sample receives the impact. When the force occurs, the elastic or plastic position changes, and the thickness is required to be ≥ 50 mm, and the thickness is required to be ≥ 10 times the penetration depth of the indentation. The corresponding indentation depth of the 25-65HRC steel is about 14~7um, so it can be applied to very thin materials, but the total thickness (substrate + plating) needs more than 2mm. The radius of curvature of the sample has a close relationship with the volume of the material involved in the formation of the indentation. It is required that the convex surface sample R ≥ 10 mm, and the measured value of the concave surface test R ≥ 15 mm is related to the projection of the contact area of the indentation. And because of the measurement under load, it is not affected by the radius of curvature.