Chromate inhibition of environmentally assisted fatigue crack propagation of aluminium alloy AA 2024-T3 in 3.5% NaCl solution

摘要: Abstract Aluminium alloy AA 2024-T3 has been used in aircraft construction for over the years due to its high strength weight ratio, extremely good damage tolerance and resistance fatigue crack propagation. However, this material is susceptible environmetally assisted propagation (EAFCP) when it exposed water vapour chloride solution. In aerospace applications, a control of EAFCP usually carried out by protective coating system that contains corrosion inhibitor. present investigation, behaviour aluminium 3.5% NaCl solution containing various levels chromate ( Cr 2 O 4 - ) inhibitor, typically 0.1%, 0.3% 0.5% studied using centre-cracked tension (CCT) specimens longitudinal–transverse (LT) orientation. The experiment was constant amplitude with stress ratio (R) 0.1 frequency 11 Hz. nature inhibitor environment electrochemical polarisation method combination optical microscopy SEM equipped EDX-spectrometer. Results investigation show additions bulk tend reduce rate, increase passivity as indicated presence anodic passivation plateaus potentiodynamic curves lower rate (da/dN) at low ΔK. mechanism inhibition on complex involving mechanical, chemical microstructural interactions discussed investigation.