Hardness can contain a number of meanings. In the metals industry, it can be thought of as a materials resistance to permanent deformation. To a metallurgist, it means resistance to penetration. To engineers, it could be resistance to wear, abrasion, or scratching. And to the machinist, it means ease or resistance regarding machining.
Hardness Testing Methods
Measuring Hardness can be indicated in a variety of ways. A few common methods used are:
- Static indentation tests: A ball, cone, or pyramid is forced into the surface of the metal being tested. The relationship of load to the area or depth of indentation is the measure of hardness, such as in Brinell, Knoop, Rockwell, and Vickers hardness tests.
- Rebound tests: An object of known mass and dimensions is bounced from the surface of the workpiece being tested, and the height of rebound is the measure of hardness. The Scleroscope and Leeb tests are examples.
- Ultrasonic testing: A type of indentation test
Why Perform Hardness Testing?
All hardness testing is meant to determine certain aspects of the metal so that engineers can decide if the metal is right for the intended purposes. It is often coupled with other empirical tests, because manufacturers and engineers need to know if the metal can meet multiple requirements. However, these tests have to be done independent of each other.
As an example under the API 5L specification pertaining to line pipe (petroleum) – Identifying the correct pipe grade will determine the correct weld procedure. The problem is that chemistry alone cannot identify the material. Some mechanical properties are need for true identification.
This is where hardness comes into play. Hardness tests can be used to determine tensile and/or yield strength, which when combined with the chemistry can accurately provide the information needed.
This is one reason that Verichek has added this service to our growing list of offerings. Verichek wants to provide our customers with the most comprehensive information to help them make the most informed decisions.
Hardness Testing Equipment
When performing hardness testing, Verichek has chosen to use the Proceq Equotip 550. This is a portable unit so it can be used both in the lab and in the field. It is also versatile in its testing method and can use stand alone or combined versions of the Ultrasonic and Leeb methods. Utilizing various probe configurations, the 550 is able to test standard plate, sheet, and bar material as well as pipes, contours, small pieces, welds, and hard to access areas.
A couple other features to note:
- With a built in computer, you can begin analyzing the results as soon as the testing is complete.
- The software includes an automatic verification process and a customizable set of reporting functions.
Because it provides results for different testing methods, Proceq’s Equotip 550 is used in a wide range of industries, including Aerospace, Automotive, Gas, Oil, and Steel Working. It is also incredibly durable so that it can be used in the field without having to worry as much about whether it will withstand some harsher conditions.
Since Hardness testing is something that our clients have requested in the past, Verichek has not only added this service to our customers, it is a new scope to our ISO Accreditation.
Have a Question about Hardness Testing?
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