Structure and properties of C92900 antifriction bronze produced by upward continuous casting

Antifriction tin bronzes are used in the aerospace industry to manufacture components that operate in friction assemblies at elevated temperatures. This is due to the alloy’s favorable combination of antifriction, mechanical, and corrosion properties. In particular, tin bronze C92900 (alloy Cu–10Sn–3Ni–2Pb (wt. %)) is widely used in such applications. It is employed in the production of braking system components and plunger pump parts. Currently, these parts are manufactured by machining ingots produced through casting with directional solidification. However, this method has a low material utilization rate, typically between 5 % and 15 %. The most promising method for producing C92900 ingots is upward continuous casting technology, which allows the ingot dimensions to closely match those of the finished part. This significantly reduces machining effort and increases metal utilization to 95 %. This study presents the results of process development for the upward continuous casting technology of 15 mm diameter C92900 ingots. The structure and properties of the castings were also investigated. It was shown that as the casting speed increased from 90 to 360 mm/min, the volume fraction of the γ-Cu₃Sn intermetallic phase increased, while the amount of tin-based solid solution remained nearly unchanged. At the same time, the phase distribution became more refined. The macrostructure consisted of columnar and equiaxed grains. As the casting speed increased, the columnar grains became more tilted relative to the direction of heat removal. The hardness increased from 127 ± 2.73 to 136 ± 4.25 HB, and the tensile strength and elongation slightly increased up to 250 mm/min, then decreased at 360 mm/min, which was associated with the macrostructure approaching a transcrystalline form. The study also examined shrinkage cavities and segregation defects in ingots cast at 150 mm/min and analyzed their causes. Finally, the paper provides recommendations for optimal casting parameters for 15 mm diameter ingots produced by upward continuous casting technology

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