Authors: A K Vasudevan K Sadananda
Publish Date: 2010/12/08
Volume: 42, Issue: 2, Pages: 405-414
Abstract
In this article we examine the effect of aging treatment and the role of planarity of slip on stress corrosion cracking SCC behavior in precipitationhardened alloys With aging the slip mode can change from a planar slip in the underage UA to a wavy slip in the overage OA region This in turn results in sharpening the crack tip in the UA compared to blunting in the OA condition We propose that the planar slip enhances the stress concentration effects by making the alloys more susceptible to SCC In addition the planarity of slip enhances plateau velocities reduces thresholds for SCC and reduces component life We show that the effect of slip planarity is somewhat similar to the effects of mechanically induced stress concentrations such as due to the presence of sharp notches Aging treatment also causes variations in the matrix and grain boundary GB microstructures along with typical mechanical and SCC properties These properties include yield stress work hardening rate fracture toughness K IC thresholds K Iscc and steadystate plateau velocity da/dt The SCC data for a wide range of ductile alloys including 7050 7075 5083 5456 Al MAR M steels and solid solution copperbase alloys are collected from the literature Our assertion is that slip mode and the resulting stress concentration are important factors in SCC behavior This is further supported by similar observations in many other systems including some steels Al alloys and Cu alloysThe authors thank Professor Kujawski Western Michigan University for critically reading the manuscript and Dr Goswami NRL Laboratory for parting with the TEM and SEM of his work The majority of the literature data was collected at the NRL/NIST libraries over a period of 10 years by both authors The analysis was done with ONRROPO AKV KS acknowledges the support received from TDA and the US Navy NAVAIR under Contract No N0042109C0002
Keywords: