Characterization of microstructural evolution and mechanical properties of Cu-Ni-Cr alloys deformed by ECAP

In recent years, Cu-Ni-Cr alloy materials have been broadly applied in the marine industry. However, owing to its dendritic microstructure, this material is an obstacle to the manufacturing process, particularly in the metal-forming process. In this study, an equal-channel angular pressure (ECAP) process is proposed to improve the material microstructure and mechanical properties. A single pass of the ECAP was performed at room temperature, and the microstructural evolution and mechanical properties of the material were characterized. The ECAP compressed and tensioned the microstructures on the top and bottom surfaces, respectively. The microstructures on the front and back surfaces were similar because they were sheared. This also caused a tear-off of the dendritic microstructure. Based on the changes in the characterization of the microstructural evolution, the ultimate tensile strength increased by 32% to approximately 680 MPa, and the elongation decreased by 200% to approximately 8%. The microhardness distribution was irregular on the front and back surfaces, causing nonuniform deformation. However, the microhardness increased by an average of 35% to approximately 270 HV. Consequently, the nonuniform microstructural evolutions and mechanical properties of each surface must be considered when applying the ECAP process to improve the mechanical properties of Cu-Ni-Cr alloy materials.