Experimental study and 3D cellular automata simulation of corrosion pits on Q345 steel surface under salt-spray environment

The evolution laws of Q345 steel pitting corrosion are introduced using a salt-spray corrosion test. The number and maximum depth of corrosion pits are counted and a mathematical model is established. 3D cellular automata is adopted to reproduce the initiation and growth processes of corrosion pits simultaneously. The results demonstrate that the cellular automata model can better reflect the evolution randomness and time-dependent laws. Within the cellular automata model, the maximum depths are controlled mainly by the corrosion reaction probability P-c and probability of downward movement P-d, whereas the pitting shapes are governed by the passivation reaction probability P-p.