Abstract
In the previous report (Tetsu-to-Hagane, 48 (1962) 6, p. 776), the anthors reported the effect of Ni and Mo content on structures of Ni-Cr stainless steels and the effects of structures on mechanical properties.
This paper describes the effects of structures, mainly those of δ ferrite on corrosion resistance to nitric acid and sulfuric acid and also describes the relation between corrosion potential in both acids and compositions and structural conditions.
Precipitatipn of chromium carbide and decomposition of δ ferrite to σ phase resulted in an increase in corrosion rate in nitric acid.
Corrosion resistance to sulfuric acid was increased with Mo content while that of specimens aged at 750°C was decreased with increasing Mo content when excess molybdenum was added.
It seems that δ ferrite had a bad effect on corrosion resistance to sulfuric acid. Potential of δ ferrite was higher than that of matrix in nitric acid but was lower than that of matrix in sulfuric acid.
