Penetrant and Filtered Particle Inspection Techniques of Additive Manufactured Parts

Traditional liquid penetrant (PT) testing approaches, particularly with high sensitivity dyes, has limited the expansion of PT into additive manufactured (AM) parts, particularly metallic AM parts. Filtered particle nondestructive evaluation techniques have been used on porous materials, such as pre-fired ceramics since technique was developed in the 1950s and has the potential to aid in the nondestructive testing of flaws in additive manufactured parts with porous surfaces. However, additive manufactured parts may still contain features which do not lend themselves to external observation. Commercially available radiocontrast agents for industrial and aerospace radiographic testing (RT) are nonexistent, however incorporation of a radiocontrast particle into a carrier and application of the agent per the filtered particle technique has the potential benefit to aid RT in the detection of crack-like flaws in unobservable features of AM parts.

A Summary of NDE of Additive Manufacturing (AM) Efforts in NASA, presented at QNDE, in July 2014 identified challenges associated with traditional NDE methods for additive manufactured parts: “One of the prominent features of AM parts is higher levels of porosity compared to conventional wrought, cast or molded parts. The irregular or rough surfaces present in these parts make traditional NDE methods for the detection of surface defects difficult to impossible. For example, PT of an as-manufactured Ti-6Al-4V specimen highlights the fact that PT may not be a realistic method or inspection of porous or rough AM parts without post-process machining and polishing”

• Potential for further development of filtered particle techniques, and those specific to AM parts.
• Filtered particle inspection, much like PT, presents a relatively inexpensive NDE compared with other methods. This is a useful cost savings if critical flaw locations coincide with visually accessible areas.
• Improve the crack detectability of RT techniques.
• Understand the fatigue behavior of AM components and NDE methods that can be used to monitor life.
• Has potential for inspection of coated parts (e.g. anodized or oxidized) or for inspection of porous coating defects.

This is early/mid-stage (TRL 2) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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