Beryllium copper (Cu-Be alloy) was bonded to austenitic stainless steel by explosive welding. The effect of aging treatment for the Cu-Be alloy on the interfacial microstructures and the mechanical properties of the joints was investigated. Before bonding, the Cu-Be alloy was solution-treated at 1073 K for 1.8 ks (1800 s) and then aged at 588 K for 3.6 and 10.8 ks. A wavy interface was formed in the joints with the non-aged and aged Cu-Be alloys. These joints differed markedly in the wavelength and the amplitude of the interface due to precipitation hardening of the Cu-Be alloy. However, fine grains of about 50 nm in diameter were observed along the collision interface in these joints. The formation of the fine grains is considered to be the trace of melting and subsequently rapid solidification at the contact surface of the Cu-Be alloy. The high hardness of the aged Cu-Be alloy was retained even after explosive welding, and the joint with the Cu-Be alloy aged at 588 K for 10.8 ks showed a bonding strength of about 700 MPa. On the other hand, the joint with the non-aged Cu-Be alloy was aged at 588 K for 10.8 ks after welding, and its bonding strength reached about 700 MPa. This indicates that explosive welding, which is characterized by extremely narrow heat-affected zone, is suited to the bonding method for the precipitation hardening Cu-Be alloy. The explosively welded Cu-Be alloy/carbon steel joint was also prepared, and the same tendency was recognized.
Beryllium copper, Steel, Explosive welding, Aging treatment, Precipitation hardening