Other Causes of Fastener Failures

Recently the failure analysis department at SMT &1 in Huntington Beach created a brief survey of fastener failures analyzed by the group over a ten-year period and found that there were four predominant failure mechanisms accounting for 77% of the fastener failures analysis by SMT&I personnel. These predominant failure mechanisms were categorized as fatigue, hydrogen embrittlement, stress corrosion cracking and overload. In general, most people working in the fastener industry have experienced or dealt with one or more of these major failure mechanisms and will sometimes elect not to perform a full failure analysis because they are "familiar" with these failure mechanisms or because the cost of the analysis exceeds the replacement costs of the fasteners. However, there are numerous other failure mechanisms that are not as prevalent and may not appear as often in the fastener and precision formed parts manufacturing industry. This article presents three such failure mechanisms encountered by SMT&I failure analysis personnel.