2020 年 59 巻 1 号 p. 100-104
High strength copper dilute alloys are expected to apply alternative heat-exchanger tube material. However, strength of materials is reduced by brazing during process of a heat exchanger. So, it was thought to be important that the decrease in strength can be suppressed by controlling the microstructure with the cooling rate. In this study, we investigated the effect of the cooling rate on the aging characteristics after brazing simulated heat-treatment of Cu-Ni-P alloy. Hardness of the specimens as simulated brazing heat-treatment after cooling decreased with increasing cooling rate. From these results, there is a correlation between the cooling rate and the initial hardness after simulated heat-treatment of brazing. Therefore, it is considered that the increase in hardness immediately after cooling is caused by precipitates formed in the cooling process after the simulated heat-treatment by brazing. The peak hardness of specimens with furnace cooling, which was the lowest cooling rate in this study, aged at 498K was achieved the maximum hardness, which was approximately 130 HV. These results suggested that the strength of the Cu-Ni-P alloy can be further increased by controlling the cooling rate after simulated heat treatment of brazing.
