loka23...
Magnetic particle and fluorescent dye penetrant inspection procedures can be successfully accomplished on 17-4PH CRES, any hardness condition.
The NDI procedures callout you outlined is incomplete, IE: (a) Liquid Penetrant testing per ASTM E 1417 or (b) Magnetic particle testing per AMST E 1444
DO YOU KNOW WHY????
When I specify magnetic particle and/or fluorescent dye penetrant inspection for Aircraft parts I typically do so as follows...
Fluorescent penetrant and/or magnetic particle inspect per MIL-STD-1907** Grade A.
**MIL-STD-1907 INSPECTION, LIQUID PENETRANT AND MAGNETIC PARTICLE, SOUNDNESS REQUIREMENTS FOR MATERIALS, PARTS AND WELDMENTS
This spec is applicable to materials, parts and weldments. It ALSO includes [as part of the Grade A, B, C, D system] all elements required for a successful NDI process callout: when-to, how-to, what-to, etc... and is very specific as to accept/reject criteria.
The 'how-to' ASTM specs you cited do NOT describe vital defect accept-reject criteria. MIL-STD-1907 lists very specific defect types/sizes/densities [#-per unit surface area] that are permitted within the grade category.
NOTE. I recommend a quick and dirty way to add a more rigorous/generalized accept-reject criteria, to the proposed callout (a) Liquid Penetrant inspect per ASTM E1417 or (b) Magnetic particle inspect per ASTM E1444., thus...
add...
NO detectable defects permitted during final NDI inspection after blending-out all defect indications to maximum limits as permitted by [drawing][repair data][etc].
Regards, Wil Taylor
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