Microstructural evolution and deformation behavior of copper alloy during rheoforging process

A complete rheo-forming process was carried out to investigate the rheoforging process of C3771 lead brass valve, starting from the semi-solid billet preparation to rheoforging experiments and material performance tests. The near-spherical micro-grains with mean equivalent diameter of 56.3 μm, shape factor of 0.78 were obtained when the raw C3771 lead brass were rotary swaged to a radial strain of 0.22 and then heated to 895 °C for 5 min. The Forge 3D software was used to analyze the temperature, strain and strain rate distribution of copper valve for obtain the reasonable process parameters during the subsequent rheoforging process. The experiment results showed that near-spherical micro-grains were stretched and refined to about 35.7–43.4 μm in different positions due to the dynamic recrystallization during the rheoforging process. The cap thread and nut thread failure torque of the so-produced valve are also discovered to be higher than the traditionally forged copper valve with dendrite micro-grains, with an enhancement of the cap and thread failure torque of 42.2 % and 28 %, respectively.