Do you ever wonder what is required to execute a Leeb test?
The Leeb method is categorized with other hardness testing techniques, which determine the resistance of a material to permanent damage. It’s one of the methods certified for hardness testing by the ISO 16859and ASTM A956 standards. The Leeb hardness test is a unique measurement for metallic materials’ hardness. While the other hardness tests cause an indentation by the impact of an indenter, the Leeb test method uses a rebound off a sample with sufficient weight and toughness. Let’s learn more about the Leeb hardness test method and its requirements.
I. Leeb Hardness Test
As briefly mentioned above, the Leeb hardness test method works very efficiently and accurately with samples that are rigid and have sufficient weight. Therefore, samples like sheet aluminum, small die-cast parts, and lightweight parts are typically not appropriate for the Leeb test. The Leeb hardness test is measured by the ratio of the impact velocity against the rebound. Moreover, the Leeb method can only be achieved with stationary samples that don’t easily move. The lesser the sample rigidity, the more likely it is to get an inaccurate result. Typically, the impact velocity ranges between 1.4 and 3.0 m/s. The Leeb hardness test can also be carried out in two different ways: using the bench hardness tester, a regular (stationary) type, and the portable (mobile) type. Advanced Leeb testers are more mobile which allows easy movement and innovative features.
II. Why is the Leeb Hardness Test Used?
The Leeb hardness test is used based on its ability to measure both ferrous and non-ferrous materials and permits fast inspection with multiple inspections. Furthermore, the Leeb hardness test can test several materials such as cast irons, copper, aluminum, stainless steel, etc. Also, the Leeb hardness test is dynamic, even though it is calculated using the Leeb scale. Additionally, it can be easily converted into other scales such as the Rockwell, Vickers, Brinell, and Shore scales. Finally, it is also very flexible and can either be done in a lab (bench testers) or physically at different test areas (portable testers).
III. How to Perform the Leeb Hardness Test?
To perform a Leeb hardness test, an impact device is stimulated towards an impact body through the aid of a spring force. This procedure often divides the velocity into three phases. The approach phase comes first, where the impact body is stimulated towards the test material’s surface via the spring force. Then the impact phase, where the impact body and the test material are in contact. This impact makes the test material plastically deformed. The elastic spring back-part on impact with the test material permits a rebound on the impact body. And finally, the rebound phase, where the impact body is stimulated out of impact through the energy already created.
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IV. Specimen Requirements for the Leeb Method
For complete and accurate Leeb testing, certain specifications must be in place. These requirements include the appropriate weight sample, typically from 5kg and above. In addition, a plane sample is touted to present a better testing surface, resulting in a more precise calculation — the smoother the surface, the better the accuracy. Conclusively, the sample must be thick enough and have an adequate absorption coating on the surface. And when preparing the test material surface, operators must be careful not to alter the surface coating by excessive grinding to avoid heat treating.
Related Article: What are the Specimen Requirements for the Rockwell Method?
Related Article: What are the Specimen Requirements for the Vickers Method?
Essentially, the Leeb hardness test is a dynamic hardness testing method that can still be converted to other hardness testing methods’ scales. Although, its accuracy is hinged on fulfilling certain specifications, which, if carefully considered, benefits its users. Furthermore, the Leeb hardness testing method is quite seamless in the face of all stated requirements and guidelines. Therefore, would you consider the Leeb hardness testing method for your material testing purpose? We leave you to ponder on that.