Articles 

Analysis of a Premature Failed Fastener Reveals Improper Heat Treatment

2011-02-23

In service performance of fasteners rely on the proper heat treatment, which has unique mechanical properties for the designed application. While the mechanical properties of some grades of stainless steels can only be alter by cold working, others may be precipitation hardened. Heat treatments vary drastically even in the class of precipitation heat treatable stainless steels. Improper processing of these alloys can lead to significantly reduced mechanical properties and alter the failure mode. This paper addresses the failure analysis of two clips, which retained an o-ring feature on a canister. These clips were put into service with a temperature range of 50 to 120 degrees Fahrenheit, which is a suitable environment for this alloy. Metallurgical investigation into the cause of these failures consisted of a macroexamination, fractography analysis, base alloy chemical evaluation, mechanical testing, and microstructural examination.