National University of Science and Technology “MISiS”, Moscow, Russia

S. A. Tavolzhanskii, Associate Professor of Foundry Technologies and Material Art Working Department (FT&MAW), e-mail: Stavolj@gmail.com
V. E. Bazhenov, Associate Professor of Foundry Technologies and Material Art Working Department (FT&MAW), e-mail: V.E.Bagenov@gmail.com
I. N. Pashkov, Professor of Foundry Technologies and Material Art Working Department (FT&MAW), e-mail: Pashkov_prof@mail.ru

From the 70s of the 20th century the copper-phosphorus brazing alloys are used as replacement for silver bearing brazing alloys for high-temperature brazing of pure copper and copper alloys. In Russian Federation the most popular brazing alloys are PMF7 (Cu7P) and P14 (Cu6P4Sn) which typically used in the form of a 2 mm diameter wire or rods. The disadvantage of copper-phosphorus brazing alloys is their poor workability by standard deformation treatment due to the presence of a significant amount of brittle copper phosphide in the alloy structure. This makes it necessary to search for alternative technology of copper-phosphorus brazing alloys production. One of the possible technologies of wire and rods manufacturing from copper-phosphorus brazing alloys is the continuous casting technique with upward drawing (UPCAST). The mentioned brazing alloys in the world practice are not manufactured by casting. Because of that the investigation of mechanical properties, microstructure and surface quality of hot extruded and casted rods with 2.5 and 3 mm diameter of PMF7 and P14 brazing alloys were carried out. Samples for investigation were produced by “Alarm” company (Moscow). Hot extrusion was carried out on a vertical hydraulic press with a force of 300 tons. Continuous casting was carried out using experimental setup with a servomotor controlled drawing device. It has been established that the brazing alloys rods obtained by continuous casting differ from the extruded rods and have a shiny and less oxidized surface. The mechanical properties of casted rods are lower than extruded one but this is not a limiting factor for their usage. It is shown that the higher mechanical properties of the extruded rods are explained by the transformation of brittle Cu₃P matrix to plastic α-Cu matrix during the hot working. The results showed that PMF7 and P14 casted rods with a 2.5 and 3 mm diameter can be used as a replacement of hot extruded brazing alloys for pure copper and copper alloys brazing.

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