EXPLORING THE PHNOMENOLOGY AND GOVERNING MECHANISMS FOR THE LOADING RATE DEPENDENCE OF ENVIRONMENTALLY ASSISTED CRACKING IN STRUCTURAL ALLOYS

EXPLORING THE PHNOMENOLOGY AND GOVERNING MECHANISMS FOR THE LOADING RATE DEPENDENCE OF ENVIRONMENTALLY ASSISTED CRACKING IN STRUCTURAL ALLOYS

James BurnsGrand Ballroom C

While literature indicates that the applied loading rate (dK/dt) can affect environmentally assisted cracking (EAC) behavior, the quantification of dK/dt dependencies and mechanistic understanding of why the applied dK/dt influences EAC remain limited. In this study, a slow-rising stress intensity (K) framework was utilized to measure EAC kinetics over dK/dt ranging from 0.2 to 20 MPa√m/hr in Beta-C Ti, AA7075-T651, AA5456-H116, Monel K-500, 304L SS, Pyrowear 675, and Custom 465-H900 stainless steel immersed in 0.6 M NaCl at applied potentials known to promote modest EAC susceptibility. Results demonstrate that the crack growth rate (da/dt) exhibits two characteristics regimes of behavior with increasing dK/dt across multiple alloys. In particular, a ‘plateau’ regime where da/dt is independent of dK/dt was observed for elevated dK/dt, while a ‘linear’ regime where da/dt linearly scales with dK/dt was noted for slow dK/dt. These findings are analysied in the context of stress- and strain-controlled failure criteria and the environmentally modified Ritchie-Knott-Rice criteria for crack advance. The implications of these findings on recent testing standardization efforts for HEAC are then discussed.
EXTENDED ABSTRACT

University of Virginia, Charlottesville, United States of America
Tue 10:30 - 10:50
Hydrogen Embrittlement and Environmentally Assisted Cracking 
Test method and rate dependence
Posted in .