Abstract
Linear sweep and cyclic voltammetry, electrochemical impedance spectroscopy, immersion for weight loss, and open circuit potential methods were used in this study to investigate the following three topics. 1. To compare corrosion behaviors between the as-solutionized and the as-cast states of some popular conventional stainless steels and alloys. 2. To study tin addition effects on corrosion behaviors of the less-component conventional and the multi-component high-entropy alloys. 3. To explore zinc addition effects on corrosion behaviors of the less-component conventional stainless steels. The data from linear sweep voltammetry show higher inert potentials and smaller corrosion current densities for the as-solutionized than for the as-cast states in sulfuric acids, KOH, and NaCl solutions due to the more homogenization and thus the less local cell effect for the former than for the latter state. The data from linear sweep voltammetry also show the increment in the content of chromium in ferritic stainless steels from 14 wt% to 16 wt% has an equivalent effect on the corrosion behavior with the 0.3 wt% addition of tin. Data from electrochemical impedance spectroscopy and open circuit potential method manifest the effect of 0.3 wt% addition of tin generates a thicker inert film than that without tin addition does. Addition of 12 wt% tin in Carpenter 20Cb3 alloy to form Sn-modified 20Cb3 (S3) alloy shows a better result than 20Cb3. The little effect on the corrosion behavior of the tin addition is ascribed to the massive Ni3Sn2 precipitate that causes local cell effect. Addition of small amount of zinc to conventional ferritic stainless steels gives no inert phenomenon in this study due to the following two reasons. 1. The electrochemical activity of zinc is higher than that of both chromium and iron. 2. The relative density of the sintered Zn-containing samples is lower than that of the melted samples. The above evaluating methods for corrosion of steels and alloys in this study give consistent results.