Manufacturing process

Non-Destructive Testing

Non-destructive testing finds cracks, porosity and other defects in welds, castings and forgings without damaging the part — using methods chosen for the material, defect type and applicable code.

Process overview

Non-destructive testing evaluates materials, components and welds without permanently altering the inspected item. Methods may include ultrasonic, radiographic, magnetic particle, liquid penetrant and other techniques selected according to material and defect type. Requirements can specify method, acceptance standard, inspection coverage, personnel qualification and reporting documentation.

Surface methods detect defects that are open to or just below the surface. Liquid penetrant testing (PT) works on non-porous materials including stainless steel, aluminium and titanium. Magnetic particle testing (MT) is fast and sensitive on ferromagnetic materials such as carbon and low-alloy steels, but cannot be used on austenitic stainless steel or aluminium. Volumetric methods look inside the material: ultrasonic testing (UT, including phased array and TOFD) is widely used for welds, forgings and plate, and radiographic testing (RT, film or digital) records internal porosity and inclusions in welds and castings.

Method, extent and acceptance criteria usually come from the design code or customer specification — for example ISO 17636 for radiography of welds, with acceptance levels linked to ISO 5817. Results are only as reliable as the people performing them, so personnel certification to ISO 9712 or an equivalent scheme is commonly required. NDT may be carried out by the manufacturer’s own qualified staff or by independent laboratories and inspection bodies.

Typical capabilities & what manufacturers can produce

What manufacturers can produce

  • Weld inspection by UT, RT, MT and PT
  • Casting inspection for porosity and shrinkage
  • Ultrasonic testing of forgings, bar and plate
  • Crack detection on machined and heat-treated parts
  • Inspection reports and records for documentation packages

Capabilities under this process

Suitable materials

Materials commonly used with this process — an editorial reference, not a statement about facilities in the Metraxio network. Suitability always depends on the part and its application.

  • Carbon Steel

    MT and UT are commonly used on welds and forgings.

  • Alloy Steel

    MT and UT of forgings and heat-treated parts.

  • Stainless Steel

    PT for austenitic grades, which are not magnetic.

  • Aluminum

    PT, RT and UT for castings and welds.

  • Cast Iron

    RT and UT of castings; UT can be more difficult in coarse-grained iron.

  • Titanium

    PT and UT for aerospace and medical parts.

  • Nickel Alloys

    PT and RT of welds and castings; coarse grain can affect UT.

Relevant industries

Industries whose Metraxio industry guides list Non-Destructive Testing as a common process, with the typical use in each.

What buyers should specify

The details that make Non-Destructive Testing quotes comparable and let facilities be assessed on the right criteria.

NDT method
PT, MT, UT or RT — or as required by the code; several methods if needed.
Extent
100%, a percentage sample, or specific welds and areas.
Standard and acceptance criteria
For example ISO 5817 level, ASME Section V and VIII, or casting severity levels.
Material and geometry
Base material, thickness and access — they decide which methods are feasible.
Personnel qualification
ISO 9712 level or another certification scheme.
Reporting
Report format, images or films, and inclusion in the documentation package.
Independent witnessing
Whether an independent inspection body must witness or perform the testing.

On Metraxio these details become a structured manufacturing requirement. Processes, capabilities, materials, certifications and part size are checked against facility profiles; tolerances, finishes and inspection details travel with your drawings and are reviewed during quoting rather than used as automatic filters.

Frequently asked questions

Magnetic particle or penetrant testing?

MT is typically preferred for ferromagnetic steels because it is fast and sensitive; PT is used on non-magnetic materials such as austenitic stainless steel, aluminium and titanium.

Ultrasonic or radiographic testing for welds?

Both find internal defects. RT gives a permanent image and suits volumetric flaws such as porosity; UT is better at planar flaws such as lack of fusion and needs no radiation protection. Codes often define which is acceptable.

Who performs NDT?

Qualified personnel at the manufacturer or at independent NDT laboratories. Many buyers require ISO 9712-certified inspectors.

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