Critical Cooling Rates on Solution Treatment of Cu-Cr and Cu-Be Alloys

摘要

It is shown that certain high strength and high electrical conductivity copper alloys, Cu-Cr and Cu-Be, do not undergo sufficent age hardening by slow quenching. This problem has been recently highlighted by the increasing demand for high strength alloys in the form of a large section. In order to find out the effect of the cooling rate on the formation of a supersaturated solid solution for Cu-Cr and Cu-Be alloys, the Jominy end quench tests and the isothermal treatment and aging tests were performed. A 25 diameter times 100 mm test bar similar to the standard bar for steel was used for the Jominy tests and the 1.0 mm diameter wire for the isothermal treatment and aging tests to determine the C-curve. The results obtained are detailed. It seems that the aging characteristics were particularly influenced by the cooling rate in the temperature range near the nose of the lower C-curve. It is concluded that the critical cooling rate on solution treatment of this alloy is 55 to 60 C/sec at about 500 C.