Radiographic testing and ultrasonic testing are both effective methods of non-destructive testing (NDT).
Depending on the material, application and types of defects you’re trying to detect, one method may offer distinct advantages over the other.
So, when should you choose radiography over ultrasonic testing? Let’s take a closer look at these two NDT techniques.
Understanding the Difference Between Radiographic and Ultrasonic Testing
Both radiographic and ultrasonic testing are volumetric inspection methods, meaning they can detect flaws hidden within the full volume, or thickness, of a material — not just the defects near its surface.
The key difference is how they work.
- Radiographic testing uses X-rays to create an image of a material’s internal structure, revealing defects based on differences in material thickness or density such as porosity, voids or inclusions.
- Ultrasonic testing uses high-frequency sound waves to identify internal imperfections and changes in material properties by measuring how sound travels through and reflects within a material. Ultrasonic testing can also provide the depth of a defect, and, in most cases, requires access to only one side of the material being tested.
When Should You Choose Radiographic Testing?
1. When You Need to Detect Porosity, Voids or Inclusions
One of radiographic testing’s greatest strengths is its ability to detect, identify and characterize volumetric defects at a high level of detail, including:
● Porosity: Small pockets of gas trapped within a material
● Voids: Internal cavities or empty spaces
● Inclusions: Foreign materials trapped within a metal or weld
Radiographic testing can reveal these types of defects in detail, helping inspectors assess material integrity and identify potential quality concerns.
Meanwhile, ultrasonic testing is particularly effective at detecting cracks, delaminations and other planar defects.
2. When You Need a Visual Record of Inspection Results
Unlike ultrasonic testing, which relies on interpreting reflected sound signals, radiographic testing produces an image of the material’s internal structure.
Digital images produced by radiography provide a valuable visual record that can be reviewed, shared and archived for future reference. These records are especially useful for:
- Quality assurance and manufacturing documentation
- Compliance with industry standards
- Comparing inspection results over time
- Sharing findings with customers and engineering teams
At American Testing Services, our computerized radiography capabilities deliver high-resolution digital images without the need for traditional film or chemical processing. This enables faster turnaround times, with improved reliability and repeatability.
3. When Testing Coarse-Grained Materials
Ultrasonic testing requires sound waves to travel through a material and return signals that an inspector can interpret. Certain materials with coarse-grained structures can scatter sound waves, creating “noise” and making internal defects more difficult to detect.
When testing materials that present these challenges, such as certain types of stainless steel and coarse-grained castings, computerized radiography can provide visual insight into internal defects that might otherwise be difficult to detect.
Choosing the Right Non-Destructive Testing Method
Not sure which NDT approach is right for your application? Determining the appropriate non-destructive testing method depends on a variety of factors, such as material type, size and shape, defect type, accessibility and industry standards.
In some cases, using both radiographic and ultrasonic testing provides the most comprehensive picture of the material’s soundness without damaging its structural integrity.
Get Expert NDT Guidance from American Testing Services
At American Testing Services, our experienced technicians provide both advanced radiographic and ultrasonic testing services to help customers identify volumetric defects, verify material integrity and meet quality requirements.
Whether your application calls for radiographic testing, ultrasonic testing or a combination of NDT methods, our team is here to help you determine the best testing approach for your needs.
Because we know that turnaround time is short for the industries we serve, we offer non-destructive testing and non-destructive inspection services on your schedule. Jobs under 100 pieces typically turn around in 24 to 48 hours (large projects and research excluded), and if needed, our labs can operate 24/7 to accommodate your timeline.
Contact American Testing Services to learn more about our non-destructive testing capabilities and discuss your inspection needs.