Chemical Factors Associated with Environmental Assisted Cracking of Generic Gun Systems

摘要

In the last five years, environmental assisted cracking (EAC) has re- surfaced as a service life limiting factor for some gun system designs. In these EAC affected system designs, mechanical loading factors alone do not appear to explain this loss of service life and chemical factors are implicated. Using standard interior ballistic and non-ideal gas-wall thermochemical analyses, the effect of EAC chemical factors is evaluated for three diversely different generic gun systems encompassing the spectrum of gun system types. This analysis indicates that hydrogen assisted cracking is the type of EAC responsible for this service life limitation. The results indicate that these hydrogen producing and embrittling chemical factors include: a major effect due to the addition of lubricants, a minor effect due to pressure oscillations, a subtle effect due to gaseous water-wall reactions, another subtle effect due to wall material choice, and nearly no effect due to gaseous acid-wall reactions.