Abstract:With the development of large-scale ships and offshore petroleum engineering platforms, the demand for large size Cu-Ni alloy elbow pipe fittings is increasing .Compared with traditional ball-forming elbow, cold push elbow has higher production efficiency and batch stability of forming quality. Although cold push elbow process has great advantages, there are some defects in the forming process, such as outer wall thinning and cracking, inner instability and wrinkle, end face distortion, etc. At present, cracking and winking occur in the forming process of DN300 large Cu-Ni alloy elbow, resulting in poor surface quality and low yield. In this paper, a cold pushing model of DN300 large specification Cu-Ni alloy elbow was established by using finite element method and numerical results were carried out, the mold clearance, pushing speed and friction coefficient on the large size elbow was analyzed, and selected the appropriate combination of forming process parameters, design and manufactured DN300 large size elbow mold, the actual production was versified. The results showed good agreement with the simulation, finally the forming yield of the large size elbow was improved.