Portable Leeb Rebound Hardness Tester

What is the Portable Leeb Rebound Hardness Tester?

A portable Leeb rebound hardness tester measures the velocity of an impact body before and after striking the test surface and converts the ratio to a hardness value. It is used for large parts in the field.

Overview

A spring drives a carbide-tipped impact body against the surface at a defined speed, and a magnet and coil inside the device measure the impact and rebound velocities. The ratio of rebound to impact velocity multiplied by 1000 gives the Leeb value HL, which is then converted to Rockwell, Brinell or Vickers through relationships established for the material class. The instrument weighs a few hundred grams, needs only a clean, smooth surface and can be used on installed parts such as rolls, pressure vessels, pipelines and structural members, with impact devices of different sizes and directions of use. Limits are important: thin sections, small masses and rough or curved surfaces give unreliable results unless a support is used, and the conversion must be validated for the actual material, because the relationship depends on elastic modulus and work hardening.

How does it work?

Hardness expresses resistance to local plastic deformation. In Rockwell testing a diamond cone or hardened ball is pressed in with a preliminary and then a main load, and hardness is read from the additional depth of penetration, which makes the method fast and simple. Brinell testing presses a tungsten carbide ball at a high load and measures the impression diameter optically, giving an average value that suits coarse or inhomogeneous material. Vickers and Knoop testing use a diamond pyramid with loads from grams to kilograms and measure the diagonal lengths of the impression, which allows individual phases, thin cases and small features to be tested. Leeb rebound testing measures the velocity of an impact body before and after striking the surface, giving a portable measurement that is converted to other scales by comparison. The measured value depends on test force, indenter geometry, dwell time, surface finish and support of the specimen, so these are all defined by the standards.

What are the key features?

• Impact body with carbide tip driven by a spring
• Coil and magnet velocity measurement
• Direct Leeb HL reading with scale conversion
• Compact handheld unit with data logging
• Impact devices for different orientations and access
• Surface roughness and mass criteria stated by the maker

What are the technical specifications?

A typical portable leeb rebound hardness tester configuration offers measuring range of HL 200 to HL 960, accuracy of ± 6 HL typical, impact energy of About 11 mJ (type D), minimum specimen mass of About 5 kg unsupported, lower with coupling, minimum thickness of About 10 mm unsupported with type D and surface roughness of Ra better than 2 µm recommended. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Portable Leeb Rebound Hardness Tester is used in field inspection of rolls and large forgings, verification of pressure vessels and pipelines, structural steel and weld hardness checks and incoming inspection where parts cannot be moved. Across the wider Hardness Testing class, laboratories also deploy it for hardened and tempered steel acceptance testing, case depth measurement after carburizing or nitriding and casting and forging hardness control.

Which standards and certifications apply?

Relevant standards and methods include ISO 6508, ISO 6506, ISO 6507, ASTM E18, ASTM E10, ASTM E384, ASTM E140 and IEC 61010-1. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Verify each tester daily or per shift with a certified reference block whose hardness lies close to the working range, and record the reading, the block identity and the date. Have the machine verified annually for test force, indenter geometry, depth or optical measurement and timing, either in house with traceable devices or by an accredited body. Handle indenters carefully, inspect them for chipping, and replace damaged ones, since a chipped diamond or flattened ball biases every result. Prepare surfaces by grinding or polishing to the roughness stated in the method, support thin specimens rigidly and ensure the surface is perpendicular to the indenter. Report the scale, test force, dwell time and number of readings with every result, and treat scale conversions as estimates rather than equivalent values.

How do I select the right Portable Leeb Rebound Hardness Tester?

Select the portable tester for field checks of heavy parts, and choose the impact device to suit access and surface condition. Establish and document conversions against a bench hardness tester on the same material, because generic conversion tables are only approximate.

How does it compare with other Hardness Testing variants?

Select the scale from the material, the size of the feature and the acceptance criteria in your specification. Rockwell C is standard for hardened steel, Rockwell B for softer metals, Brinell for castings and large forgings where the impression is acceptable, and Vickers or Knoop for thin cases, coatings, welds and individual microstructural constituents. Choose the load range to cover your thinnest feature, remembering that Vickers hardness depends on load at low values. Decide whether you need a manual, digital or fully automatic machine: automatic machines with traverses and motorized stages are used for case-depth series and for high volumes, and they should store test programs so that results are repeatable. Portable rebound testers suit field inspection of large parts but need a conversion relationship established against a bench machine on the same material, and they cannot test thin sections or small parts reliably.