What is the primary purpose of non-destructive testing (NDT)?

The primary purpose of non-destructive testing (NDT) is to evaluate the properties of a material or component without causing any damage to it. This characteristic is fundamental to NDT methods, as they allow for assessment of the integrity, structural stability, and overall condition of materials in service, or before they are put into service, without compromising their usability. This enables consistent monitoring and maintenance of critical components in various industries, such as aerospace, automotive, and construction, where safety and reliability are paramount.

In contrast, other options describe activities that go beyond the scope of non-destructive testing. Improving the strength of a material involves processes that might alter its physical properties, which NDT does not do. Chemically analyzing a material's composition falls under destructive or semi-destructive methods that may not allow for subsequent use of the material. Lastly, performing physical alterations on components is not relevant to NDT, as the main goal is to inspect and assess without changing or damaging the material in any way.