The effect of phosphorus content in copper alloys used for crystallisers of continuous casting machines

One of the key elements defining the technical level and operational capabilities of continuous casting machines (CCM) is the complex of physico-mechanical properties of copper or copper alloys used in its production. The paper provides a comprehensive assessment of the possibility of obtaining high-quality copper plates for CCBC crystallizers based on domestic technologies and equipment using refined copper. Special attention was paid to the need to optimize the chemical composition of the copper alloy within a narrower range of chemical element values. The analysis of the research shows that currently used copper alloys for CCM crystallizer manufacturing have a wide range of fluctuations in the main operational properties, namely thermal conductivity (260-390 W/(m·K)) and solidification temperature (250-700 °C). However, most of the alloys used have narrower fluctuation limits for acceptable values, constituting 340-390 W/(m·K) for thermal conductivity and 300-370 °C for solidification temperature, significantly depending on the impurity content in the copper alloy. Generalizing graphical dependencies, it should be assumed that the rational phosphorus content in the alloy is in the range of 40-120 ppm. In this case, the thermal conductivity of the alloy will be in the range of 370-400 W/(m·K), the solidification temperature will be 410-440 °C, and the recrystallization start temperature will be 370-400 °C. Moreover, such a phosphorus content interval is technologically feasible to maintain during billet casting. It is also shown that normalization annealing after cold deformation in the temperature range of 320-350 °C is capable of increasing the thermal conductivity of the alloy by 1-2 %. As a result of the conducted research, optimal limits of phosphorus content in fire-refined copper were established, ensuring the level of its physico-mechanical properties not lower than the indicators characteristic of alloys obtained from cathode copper. However, besides phosphorus, other alloy impurities, the content of which differs from the values characteristic of alloys obtained from cathode copper, may affect the properties of the material made from refined copper. Therefore, further research will focus on studying their complex impact on the physico-mechanical properties of refined alloys.