Radiographic testing (RT)

Visualizing internal structures – penetrating and precise

Radiographic testing is based on the varying permeability of materials to ionizing radiation. The component is irradiated with X-rays or gamma rays. The radiation is attenuated to varying degrees depending on material density, thickness, and internal irregularities.

Behind the component is a detector – such as film, a digital flat-panel detector, or an image plate system – that captures the transmitted residual radiation. Areas with higher material density absorb more radiation and appear brighter in the image, while areas with lower density or voids are displayed as darker.

If there is a defect inside the component, such as a shrinkage cavity, porosity, or bonding defect, this locally alters the radiation absorption. This creates a contrast difference in the captured image, allowing conclusions to be drawn about the location, size, and shape of the irregularity.

Image evaluation is performed using defined evaluation standards, reference specimens, or contractually agreed-upon criteria. Depending on the inspection task, different radiation sources, energy ranges, and exposure parameters are used to ensure sufficient image quality and inspection reliability.

X-ray inspection thus enables a two-dimensional representation of the internal condition of the component and is an established volumetric inspection method, particularly for castings, welds, and complex geometries.

What defects or features are inspected?

X-ray inspection is particularly effective at detecting the following features:

• Internal cavities and porosity in castings
• Weld defects or irregularities in welds
• Inclusions or material separations
• Inhomogeneities in the material structure

The advantages of X-ray inspection at a glance

X-ray inspection is a proven imaging method for the volumetric evaluation of components and offers the following advantages in particular:

• Volumetric representation of internal structures
• Permanent documentation through image recording
• Detection of porosity, cavities, and bonding defects within the material
• Suitable for complex geometries and thick-walled components

In which applications is X-ray inspection useful?

X-ray inspection is used when information about the internal structure of a component is required. Typical applications include inspections following casting or welding processes, as well as quality control of safety-critical components.

It is suitable for both individual inspections and in-process sampling inspections.

In which industries is X-ray inspection typically used?

X-ray inspection is primarily used in industrial sectors where the internal condition of safety-critical components must be evaluated:

• Automotive and supplier industry
• Aerospace
• Mechanical and plant engineering
• Energy and power plant industry
• Pressure vessel and piping construction
• Foundry industry

The specific design of the inspection depends on the material, density, material thickness, component geometry, and the respective inspection requirements.

Which standards are relevant?

X-ray inspection is performed in accordance with the relevant standards and customer specifications, for example, in accordance with DIN EN ISO 17636 or comparable international regulations.