Discussion by Henry Paige, Philadelphia, Pa.:
Mr. Works has ably presented an important corrosion phenomenon encountered in the use of stainless steels and a practical solution to the problem of sensitization. However, to fully understand the basic mechanisms involved, the following metallurgical features should be emphasized.
As pointed out by the author, when sensitization occurs at moderate temperatures examination of the structure shows the presence of a carbide network at the grain boundaries and resistance to corrosion is diminished. But the carbide particles per se are not the cause of this diminished resistance. Rather, it is due to the fact that when chromium carbide is precipitated at the boundary, a zone depleted of alloy content is necessarily left adjacent to the particles.
Using the concepts of Uhlig,1 it is then possible to calculate the minimum amount of chromium necessary in solid solution to preserve passivity. On the basis...
