THE USE OF XRD FOR NON-DESTRUCTIVE CERTIFICATION AND VALIDATION OF CRYOGENIC TREATMENT

Deep cryogenic treatment (DCT) is a post-heat treat, cold thermal process that results in improvement to wear life, tensile strength, fatigue, conductivity and corrosion. The process does not change dimensional size or show visual signs of process application. However, neither DCT providers or standards agencies have yet to formalize a process acceptance test, validation procedure or certification method for DCT.

While heat treating uses the widely accepted ASTM E18 Rockwell hardness test to conform to certification procedures established by NADCAP and ASTM, hardness is not materially changed by DCT thus it is ineffective as a validation test. Other low cost, non-destructive tests such as ultrasonic, eddy current and mag particle have wide scatter, often inaccurate results and require significant technician training.

X-ray diffraction (XRD) is an existing, non-destructive industry-approved test (ASTM E2860 standard for residual stress measurement) that can be used to validate use of a thermal process (both heat treating and DCT) and quantitatively measure improvements that may extend the life of parts subjected to thermal treatments. XRD is a low cost, fast and highly accurate, field use test that can reliably become the industry certification standard for DCT.