Abstract:The large-diameter copper crystallizer is an important component of vacuum smelting equipment for precious metals such as titanium alloys and nickel based alloys. The crystallizer uses large-diameter seamless copper pipes with a longer lifespan. The extrusion method is one of the most suitable methods for manufacturing large-diameter seamless copper pipes compared to centrifugal casting and forging methods. The copper pipes obtained by the extrusion method have uniform microstructure and better mechanical properties. The extrusion process parameters have a significant impact on the performance of copper pipes, but there is currently no research on the extrusion process parameters for large-diameter copper pipes. This article investigated the effects of heating temperature and extrusion deformation on the extrusion pressure, grain size, and mechanical properties of large-diameter copper pipes. The results showed that the higher the heating temperature of the billet for large-diameter copper pipes, the lower the maximum extrusion pressure, but the decrease gradually decreased with the increase of temperature. The maximum extrusion force was mainly composed of the plastic deformation force of red copper and the friction force with the die. The plastic deformation force was proportional to the natural logarithm of the extrusion ratio. The grain size increased with the increase of heating temperature and the decrease of extrusion ratio. The heating temperature was 780~860 ℃ and the mechanical properties of the extrusion ratio were similar between 5.4 and 6.4. The seamless copper pipes produced by extrusion under this process window all met the requirements of product technical indicators.