Effects of compressive stress on localized corrosion in AA2024-T3

Abstract

The effect of compressive stress on intergranular corrosion (IGC) of AA2024-T3 was studied using a constant load and simultaneous electrochemical measurement. A specially designed electrochemical cell was used to compress a pillar-shaped sample and control the potential at a value that promoted IGC. The extent of IGC was assessed by metallurgical cross-sectional images. The effect of the compressive stress depended on the orientation of the stress relative to the elongated microstructure. Application of a compressive stress halfway to yield in the S or through-thickness direction significantly reduced the growth kinetics of IGC in the longitudinal direction, but did not eliminate it totally. The strain change during exposure also was used to quantify the change in radius of the cylindrical sample as a function of time during IGC growth. The effect of compression on reducing IGC was also assessed by the current density measured during potentiodynamic and potentiostatic polarization. The effects of residual compressive stress on IGC were studied using samples treated by low plastic burnishing (LPB), which produces a surface layer with high residual compressive stress. The results depended on the plane of the LPB treatment. A micro-capillary cell was used to measure corrosion behavior at different zones of the section of an LPB-treated sample. The breakdown potential was significantly higher in the zone with residual compressive stress than in the interior of the sample.

Mechano-electrochemical modelling of corroded steel structures

“…Previous studies have focused on stress corrosion cracking [6,7], corrosion fatigue [8][9][10] and hydrogen-induced cracking [11][12][13] and erosion-corrosion [14][15][16]. It has been reported that 23-33% of the low-alloy steel weight loss was attributed to the mechano-electrochemical effects, while the number could be 55-62% for austenitic stainless steels [17].…”

“…Under external load, it has been generally agreed that the plastic strain will significantly reduce the corrosion resistance by directly enhancing the anodic reaction [7,11,14,16,[21][22][23][24][25][26] while the hydrogen evolution was reported to increase as well [21,22]. Despic et al [11] observed that a negative corrosion potential shifted by up to 30 times, with a marked increase in the anodic current density at the onset of the tensile plastic strain and reached an asymptotic value gradually.…”

An Industrial Perspective on Environmentally Assisted Cracking of Some Commercially Used Carbon Steels and Corrosion-Resistant Alloys

“…The main purpose of the shot-peened layer is to provide compressive stress on the surface to mitigate the initiation of fatigue cracks. In addition, the beneficial effect of compressive stress on localized corrosion is reported by Liu et al 16 and Peyre et al 17 The surface condition of shot-peened carbon steel affects the formation and adhesion of the ZnP layer and the organic coatings. Zinc phosphate crystals protect the metal surface from corrosion and provide a suitable interface for bonding with top coatings.…”

Analysing the coupled effects of compressive and diffusion induced stresses on the nucleation and propagation of circular coating blisters in the presence of micro-cracks

“…Stress corrosion cracking (SCC), due to microcracks opening in a corrosive environment, results when the materials are subjected to tensile residual stress in a corrosive environment [5][6][7]. Contrary to this, compressive residual stress causes the contraction of micro-cracks resulting in the inhibition of corrosion which proves beneficial for the control of SCC [8,9]. It is implied that the micro-cracks behaviour in materials correlate to the residual stresses in the materials.…”

“…⍺ c > ⍺ s , the positive temperature diversification (∆T > 0) from its fabrication temperature will induce compressive residual stress in the coating [9,[32][33][34][35]. The pre-exiting micro-cracks in coating will gradually contract with increasing compressive residual stress on temperature rise.…”