Contact Our Experts
Send us a Email, we will feedback to you ASAP!
Home > Testing Types > Leeb
The Leeb hardness testing, otherwise called as Leeb Rebound Hardness Test (LRHT), is considered as one of the four commonly used methods to test the hardness of the metal. It is a type of non-destructive testing used to inspect large sized workpieces weighing above 1 kg. It also measures the coefficient of restitution.
Unlike other stationary traditional methods including Rockwell, Brinell, and Vickers which were implemented only in the laboratories or testing areas, the Leeb method proves to be portable by achieving high testing rates at a reduced cost.
How to measure hardness by Leeb hardness tester?
The hardness of metallic materials can be determined as per the ISO 16859 and ASTM A956 standards.
In the Leeb hardness testing method, the hardness value can be calculated from the energy loss of an impact body after impacting upon a metal. This Leeb quotient is equivalent to the measure of that energy loss due to deformation. The impact body rebounds faster from harder samples than the softer ones, resulting in a larger value 1000* vr / vi which is quoted as the Leeb rebound hardness unit HL.
When an impact device accelerates an impact body with the help of spring force, the velocity of the impact body gets segregated into three phases:
These velocities are measured without any contact through an induced voltage, produced by a magnet moving in a defined coil of the impact device. This induced voltage is logged electronically where the peak values, the point of the impact phase as well as the rebound phase, are used to determine the Leeb hardness, as seen in the figure below. The ratio of the rebound velocity (vr) to the impact velocity (vi) multiplied by a factor of 1000, shows the Leeb hardness value (see the formula below).
Rebound velocity vr
HL = ————————— * 1000 = —- * 1000
Impact velocity vi
Legend:
A – Peak value of the approach phase
B – Peak value of rebound phase
t – Time
U – Voltage
Classification of the Leeb hardness test
There are seven hardness testing methods that vary from each other with respect to three factors namely:
These differences between the various hardness testing methods are listed in the following table:
Test method | Impact velocity [m/s] | Kinetic impact energy [mJ] | Rebound velocity [m/s] | Maximum distance between indenter ball and test surface [mm] | Material of indenter | Mass of impact body [g] | Spherical radius [mm] | Application range |
HLC | 1.4 | 3.0 | 0.49 – 1.344 | 2.00 | WC-Co | 3.1 | 1.5 | 350 – 960 HLC |
HLD | 2.05 | 11.5 | 0.615 – 1.8245 | 2.00 | WC-Co | 5.45 | 1.5 | 300 – 890 HLD |
HLDL | 1.82 | 11.95 | 1.1092 – 1.729 | 2.00 | WC-Co | 7.25 | 1.39 | 560 – 950 HLDL |
HLD+15 | 1.7 | 11.2 | 0.561 – 1.513 | 2.00 | WC-Co | 7.75 | 1.5 | 330 – 890 HLD+15 |
HLE | 2.05 | 11.5 | 0.615 – 1.886 | 2.00 | PCD | 5.45 | 1.5 | 300 – 920 HLE |
HLG | 3.0 | 90.0 | 0.9 – 2.25 | 3.0 | WC-Co | 20.0 | 2.5 | 300 – 750 HLG |
HLS | 2.05 | 11.4 | 0.82 – 1.886 | 2.00 | C | 5.40 | 1.5 | 400 – 920 HLS |
There are two types of Leeb hardness testers such as bench (stationary, classical) as well as portable (mobile, electronic).
Application of Leeb hardness testing
There are various applications of Leeb hardness testers which are listed below:
You tell us what you want, and we tell you our solution.
WhatsApp us
Send us a Email, we will feedback to you ASAP!