science

Leeb rebound hardness test

Leeb rebound hardness test is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Leeb rebound hardness test rather than just read about it. In short: The Leeb Rebound Hardness Test (LRHT) invented by Swiss company Proceq SA is one of the four most used methods for testing metal hardness. This portable method is mainly used for testing sufficiently large workpieces (mainly above 1 kg).

Key takeaways

Leeb rebound hardness test belongs to science; place it in that map before memorising details.
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Reproduce the core statement of Leeb rebound hardness test from memory before moving on to harder problems.

Reference excerpt

The Leeb Rebound Hardness Test (LRHT) invented by Swiss company Proceq SA is one of the four most used methods for testing metal hardness. This portable method is mainly used for testing sufficiently large workpieces (mainly above 1 kg). It measures the coefficient of restitution. It is a form of nondestructive testing.

History The Equotip (later on also called simultaneously as Leeb method) rebound hardness test method was developed in the year 1975 by Leeb and Brandestini at Proceq SA to provide a portable hardness test for metals. It was developed as an alternative to the unwieldy and sometimes intricate traditional hardness measuring equipment. The first Leeb rebound product on the market was named “Equotip”, a phrase that still is used synonymously with “Leeb rebound” due to the wide circulation of the “Equotip” product. Traditional hardness measurements, e.g., those of Rockwell, Vickers, and Brinell, are stationary, requiring fixed workstations in segregated testing areas or laboratories. Most of the time, these methods are selective, involving destructive tests on samples. From individual results, these tests draw statistical conclusions for entire batches. The portability of Leeb testers can sometimes help to achieve higher testing rates without destruction of samples, which in turn simplifies processes and reduces cost.

Method The traditional methods are based on well-defined physical indentation hardness tests. Very hard indenters of defined geometries and sizes are continuously pressed into the material under a particular force. Deformation parameters, such as the indentation depth in the Rockwell method, are recorded to give measures of hardness. According to the dynamic Leeb principle, the hardness value is derived from the energy loss of a defined impact body after impacting on a metal sample, similar to the Shore scleroscope. The Leeb quotient (vi,vr) is taken as a measure of the energy loss by plastic deformation: the impact body rebounds faster from harder test samples than it does from softer ones, resulting in a greater value 1000×vr/vi. A magnetic impact body permits the velocity to be deduced from the voltage induced by the body as it moves through the measuring coil. The quotient 1000×vr/vi is quoted in the Leeb rebound hardness unit HLx (where x indicates the probe and impact body type: D, DC, DL, C, G, S, E) . While in the traditional static tests the test force is applied uniformly with increasing magnitude, dynamic testing methods apply an instantaneous load. A test takes a mere 2 seconds and, using the standard probe D, leaves an indentation of just ~0.5 mm in diameter on steel or steel casting with a Leeb hardness of 600 HLD. By comparison, a Brinell indentation on the same material is ~3 mm (hardness value ~400 HBW 10/3000), with a standard-compliant measuring time of ~15 seconds plus the time for measuring the indentation. Theoretical background of the rebound hardness test is discussed in detail in.

Scales Depending on the probe (“impact device”) and indenter (“impact body”) types that vary by geometry, size, weight, material and spring force, diverse impact devices and hardness units are distinguished, e.g.:

Equotip impact device D with hardness unit HLD Equotip impact device G with hardness unit HLG Equotip impact device C with hardness unit HLC Equotip impact device E with hardness unit HLE Equotip impact device DL with hardness unit HLDL Equotip impact device S with hardness unit HLS Equotip impact device DC with hardness unit HLDC Generally, impact device types are optimized for certain application fields. This is similar to using various indenter geometries and test loads in Rockwell (e.g. HRA, HRB, HRC), Brinell and Vickers. Equotip hardness results in HLx are often converted to the traditional hardness scales HRC, HB and HV mainly for convention reasons between supplier and customer.

Standards DGZfP Guideline “Mobile Härteprüfung“ VDI/VDE Guideline 2616 Part 1 “Hardness testing of metallic materials” American standards: ASTM A956 “Standard Test Method for Leeb Hardness Testing of Steel Products” ASTM E140 - 12be1 "Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness" International standards: ISO/DIS 16859-1 "Metallic materials - Leeb hardness test - Part 1: Test method" ISO/DIS 16859-2 "Metallic materials - Leeb hardness test - Part 2: Verification and calibration of the testing devices" ISO/DIS 16859-3 "Metallic materials - Leeb hardness test - Part 3: Calibration of reference test blocks"

Worked examples

Example 1 — a first encounter with Leeb rebound hardness test

Start with the simplest possible case. Write down what Leeb rebound hardness test claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Leeb rebound hardness test before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Leeb rebound hardness test ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Leeb rebound hardness test

In research: Leeb rebound hardness test appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Leeb rebound hardness test in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Leeb rebound hardness test is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hardness tests, so understanding it makes those chapters shorter.
In everyday life: Look for Leeb rebound hardness test outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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Frequently asked questions

What is Leeb rebound hardness test in simple terms?

Why does Leeb rebound hardness test matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Leeb rebound hardness test?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Leeb rebound hardness test.