Influence of additional elements on the season cracking susceptibility of Cu-30 mass%Zn alloy

Cold worked Cu-Zn alloys possess very high season cracking susceptibility. It is expected that the season cracking susceptibility of Cu-Zn alloys is reduced by adding appropriate elements. However, little is known about the relation between additional elements and the nature of the surface oxide film which is formed during the exposure in the anmonical environment. In this paper, we intend to examine the effect of additional elements and cold working on the season cracking susceptibility of Cu-Zn alloys, and to develop a new Cu-Zn based alloy with a much lower susceptibility and good cold workability. The results obtained under the JIS test condition indicate that a Cu-30 mass% Zn-1 mass% Si alloy has the lowest season cracking susceptibility which is nearly the same as that for Cu-20 mass% Zn alloy, due to the suppression of the formation of surface Zn-rich oxide film during exposure in an ammonical environment.