THE METHOD OF AVOIDING HEAT BRACKET OF PIPE BILLS MADE OF AMg6 ALLOY WHEN CASTING IN MOLDS BY OPTIMIZING THE TEMPERATURE PARAMETERS OF CASTING AND USING VIBRATION

Procesi littâ, 2023, Vol 3 (153), 12-17

Abstract

On the basis of the analysis of the problems of the formation of hot cracks, the optimization of the casting parameters in the mold of tube blanks from the AMg6 alloy under the influence of vibration to reduce their hot brittleness was carried out. The analysis of publications on this data revealed that many methods of assessing the sensitivity to the formation of hot cracks have been developed in the world, but the study of the problem of hot brittleness during casting in a mold of tube blanks made of AMg6 alloy has not been conducted, which determined the relevance of such studies. In the course of experimental studies, it was found that the tendency to the formation of hot cracks depends not only on the malleable or non-malleable form, the temperatures of heating the form and the melt before pouring, but also on its chemical composition, therefore, experimental studies were conducted only for one case of AMg6. The ring test developed by Singer and Jennings [3] was used to check hot brittleness. During the experiments, three ring samples for hot brittleness were cast in a steel mold under different casting conditions. According to the results, the parameters of casting in the mold of tube blanks from AMg6 alloy under the influence of vibration to reduce hot brittleness were optimized. It was found that hot cracks occur due to casting in an unheated mold, high overheating of the melt and prolonged cooling of the casting in the mold. It was found that the processes of interaction between the mold and the casting affect the accuracy of its dimensions and can lead not only to cracks, but also to the appearance of a number of specific defects. The emergence of stresses in the casting and the mold is a consequence of their force interaction. It was found that as a result of inhibition by the mold of the linear shrinkage of the solidified casting, stresses arise that can either destroy the casting or compress the inner mold so much that it will be very difficult to separate the casting from the mold. It was found that vibration processing
during pouring leads to healing of hot cracks, improvement of mold shedding, compaction of the metal structure, but complicates the separation ability when separating the casting from the mold. According to the results of graphical optimization, the following optimal casting parameters were determined: mold heating temperature 300 ⁰C, AMg6 melt temperature before pouring into the mold 700 ⁰C, mold vibration amplitude 0.2 mm, mold vibration frequency 4...23 Hz.