Grinder Burn - A Journey from Identification to NDT Risk Mitigation Activites

A component randomly started failing testing at high rates early in life where-as multiple previous tests successfully passed. A standard failure analysis was conducted including macro fractography, heat treatment analysis, and microstructure analysis. Within the microstructure analysis, potential evidence of grinder burn was observed in the form of untempered martensite and temper back. Acid etch testing per MIL standards was conducted and confirmed the presence of grinder burn. Testing of additional parts in inventory also showed grinder burn without an option to bookend the quality issue with thousands of parts in inventory. Thus began a quest to find the most effective, accurate, and fastest method for detecting grinder burn while also determining whether the severity was enough to cause failure or not as parts with light grinder burn did not fail. The journey included acid etching, ammonium persulfate etching, magnetic particle, and finally Barkhausen.