White-Color Cu-Zn-Mn Alloys with Low Season Cracking Susceptibility
Yasuharu YOSHIMURA, Kazuhiko KITA and Akihisa INOUE
Abstract:Manganese is one of the important elements to improve mechanical properties and control the surface color of Cu-Zn alloys. However, little is known about the mechanical property and season cracking susceptibility of the Cu-Zn-Mn alloys which contain more than 5mass%Mn. In this paper, we intend to examine the effect of manganese on the fundamental properties of Cu-Zn alloys, and to develop a new Cu-Zn-Mn alloy with much lower susceptibility and good mechanical property. The color properties of a–and b–values of the Cu-Zn-Mn alloys can be controlled by the change of Zn and Mn concentrations, and a Cu-25mass%Zn-10mass%Mn alloy has the same white color as Nickel Silver. The ternary alloy also exhibits the lowest season cracking susceptibility which is nearly the same as that for Cu-15mass%Zn alloy, by suppression of the formation tendency of surface oxide film during exposure in the ammonical environment. Key Words:Cu-Zn-Mn alloy, Season cracking, Oxide film, Exposure, Ammonia, Cold workability, Color, White