Non-destructive testing: hardness after heat treatment

Destructive and non-destructive testing in industries

What is non-destructive testing?

A non-destructive test (NDT) is a test to detect possible problems on the surface or on the inside of parts.

A non-destructive test, as its name implies, does not require the destruction of the parts, since it is based on the application of physical phenomena such as electromagnetic or sound waves, or other methods that do not involve the destruction of the sample to be tested.

This type of testing has been in existence for decades. Its origins date back to 1868, when magnetic fields were first used to detect surface cracks in railroad wheels and axles.

NDTs are used in various industries: in the automotive, aviation, construction, manufacturing, nuclear engineering and petrochemical (pipeline transport) industries, and others.

They are classified as follows:

  1. Superficial: These provide information on the surface and sub-surface state of the materials. Several tests fall under this heading: VT (visual inspection), PT (liquid penetrant) and MT (magnetic particles).
  2. Volumetric: These reveal the internal condition of the materials. It includes several tests: RT (radiography) and UT (ultrasound).
  3. Tightness: These show the degree to which fluids can be contained in a vessel without escaping to the atmosphere or in any other uncontrolled way. The most common tests used in the oil & gas industry are leak tests and pressure change tests.

What is destructive testing?

Destructive testing of materials is used to verify the physical, chemical and mechanical properties of materials and ensure that they meet the design specifications developed by engineers. Unlike non-destructive testing, these do modify the properties, structure or geometry of the parts being tested, since they serve to simulate the conditions that the samples must withstand in real life.

Destructive tests are performed in all industries whenever it is important to verify the characteristics of the materials. Iron and steel products are always tested in the state in which they will be used.

They can be performed either when the materials are manufactured and/or later in the project to ensure that the material properties have not been altered.

There are several types:

  • Chemical: Verification via procedures such as chemical analysis of components or corrosion tests.
  • Physical: Analysis of physical phenomena such as heat, light or electricity in order to measure variables such as melting and boiling points, the degree of thermal and electrical conductivity or the level of magnetism.
  • Mechanical: Subjection to mechanical forces with a given load.

In this case, it is important that the tests be conducted according to the protocols established in the regulations for each area and material/product.

Non-destructive testing in forging, practical application

In order to continue improving our NON-DESTRUCTIVE TEST capabilities —specifically in the area of measuring hardness after heat treatment— and in order to achieve greater reliability and automation in our measurements, ULMA Forged Solutions has acquired an advanced, new durometer.  Produced by the Italian company EASYDUR, it boasts milling, indentation and automatic direct reading capabilities. The durometer is manufactured in accordance with the following standards:

EN-ISO 6508 for Rockwell

EN-ISO 6506-2 for Brinell


 It is equipped with:

  • laser pointer to choose the point of indentation
  • milling station
  • indentation station with load cell
  • 2 Mpx optical camera and illumination system for automatic Brinell footprint measurement

This new hardness tester acquired by ULMA performs a complete test cycle (surface cleaning, indentation, hardness recognition, data recording) thanks to its built-in milling head, which offers numerous advantages in terms of quality, reliability and productivity.

 The machine has 3 main axes of head movement, all automatic and programmable, to position the instrument in the area to be tested. The duration of the testing cycle is about 1 minute.

By equipping the machine with the Self-Learning 4.0 system, process repeatability is ensured and operator errors are virtually eliminated.

With this new acquisition, ULMA Forja intends to strengthen its process and final determinations even further by verifying the hardness of the different batches in its heat treatment section.