Influence of technological factors of melting on the structure and properties of modified heat‑resistant chrome bronzes

Abstract

The paper presents the results of a study of the influence of technological factors of open melting on the structure and properties of modified heat‑resistant chrome bronzes. The role of protective atmospheres and deoxidizers in the formation of the chemical composition of alloys is studied and their optimal combination is proposed, consisting in a combination of Cryolite and argon to protect the copper melt during alloying with its preliminary deoxidation with a modifier based on the composition “Cu – 10 % B”, developed and produced at a pilot production facility at the Belarusian‑Russian University. An idea of the kinetics of the dissolution process of a mechanically fused modifying ligature with a high content of an alloying component and its effect on the formation of the structure of cast materials is obtained. The optimal duration of the doping time and the base temperature, depending on the size of chromium inclusions and the state of the surface of its particles, are determined. The phase composition and physico‑mechanical properties of experimental bronzes have been studied.It has been established that the use of a mechanically fused modifying ligature with a high content of alloying component having chromium particles close to micro‑/nanodisperse size with a non‑oxidized surface and a highly effective deoxidizer modifier reduces the temperature and duration of melting, obtaining alloys with a microcrystalline type of structure (2–5 microns) and a complex of physico‑mechanical properties not inferior to, and in terms of heat resistance superior analogues, which is confirmed by the data of production tests at JSC “Belcard” (Grodno, RB) of contact spot welding electrodes made of experimental bronzes, which are 3.8 times more resistant than those used by the plant.