Quantitative analysis of pitting corrosion behavior of thixoformed A356 alloy in chloride medium using electrochemical techniques

摘要

Pitting behavior of thixoformed A356 alloy, with different reheating temperatures, was evaluated and compared with the pitting behavior of rheocast and gravity-cast A356 alloy with the same composition. The presence of silicon particles lead to the development of pitting at the silicon-matrix interface. Results of galvanic corrosion simulation showed that the resistance to pitting corrosion of thixoformed samples formed at 590 ℃ was higher than the samples formed at 600 ℃ as well as rheocast and gravity-cast samples. These results relate pitting corrosion behavior of thixoformed, rheocast and gravity-cast A356 alloy to their microstructure characteristics using a new parameter in the form of λ/DV'.