IngentaConnect Pitting corrosion of thixoformed, rheocast and gravity cast A356-...

Authors: Tahamtan, S.¹; Boostani, A. Fadavi²; Nazemi, H.³

Source: Corrosion Engineering, Science and Technology, Volume 44, Number 5, October 2009 , pp. 384-388(5)

Abstract:

In the research work presented here, the pitting behaviour of thixoformed A356-T6 alloy, with different reheating temperatures, was evaluated and compared with the pitting behaviour of rheocast and gravity cast A356-T6 alloys with the same composition. To study the pitting behaviour, linear sweep voltammetric tests were performed on thixoformed, rheocast and gravity cast A356-T6 alloys in a 3·5%NaCl solution. A simulation method was also used to identify local galvanic corrosion current density between local galvanic couples. Results obtained show that the resistance to pitting corrosion of thixoformed samples formed at 590°C was higher than that of the samples formed at 600°C as well as rheocast and gravity cast samples. The improvement in the pitting corrosion resistance due to the thixoforming process is attributed to morphological aspects of the silicon phase as well as the area effect as related to galvanic corrosion between the silicon particles and the eutectic aluminium phase.

Keywords: MICROSTRUCTURE; HEAT TREATMENT; HOT WORKING; LINEAR SWEEP VOLTAMMETRY

Document Type: Research article

DOI: 10.1179/174327808X315678

Affiliations: 1: Department of Materials Science and Engineering, Isfahan University of Technology, Isfahan, Iran;, Email: tahamtan@ma.iut.ac.ir 2: Department of Materials Science and Engineering, Isfahan University of Technology, Isfahan, Iran 3: Islamic Azad University, Majlesi Branch, Isfahan, Iran

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Pitting corrosion of thixoformed, rheocast and gravity cast A356-T6 alloy in chloride media