A THOROUGH STUDY ON THIXOFORMABILITY OF THE COOLING SLOPE CAST 7075 FEEDSTOCKS: STEP-BY-STEP OPTIMIZATION OF THE FEEDSTOCK PRODUCTION AND THIXOFORMING PROCESSES


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Acar S. , Güler K. A.

INTERNATIONAL JOURNAL OF METALCASTING, vol.16, pp.1-23, 2022 (Journal Indexed in SCI Expanded)

  • Publication Type: Article / Article
  • Volume: 16
  • Publication Date: 2022
  • Doi Number: 10.1007/s40962-022-00801-0
  • Title of Journal : INTERNATIONAL JOURNAL OF METALCASTING
  • Page Numbers: pp.1-23

Abstract

The semi-solid metal forming techniques have been

researched for a long time to obtain near-net shape

products from aluminum alloys. Most of the effort was

devoted to the casting alloys such as A356 and A380 to

develop an alternative technique for high pressure die

casting process. In this study, the cooling slope casting

technique, which is an unorthodox approach to produce

semi-solid feedstocks for wrought aluminum alloys, and the

results of the following thixoforming processes were

investigated thoroughly for 7075 aluminum alloy.

According to the parameters studied and obtained results,

the lowest possible casting temperature and mild tilt angle

parameters were found to give the best outcomes for the

produced feedstocks’ physical and microstructural properties.

No significant difference was observed depending on

the slope length due to the employed low superheat during

casting processes. Reheating processes of the produced

feedstocks revealed that gradual depletion of Al from the

intergranular region and the migration of Cu to the Aldepleted

zones forms the partial melt, and the average

grain size of the reheated specimens dramatically increases

after 40 min of reheating at selected reheating temperature.

The average shape factor, grain size, and density

values of the specimen selected for thixoforming processes

were around 0.82, 96 lm, and 2.67 g/cm3, respectively.

After the thixoforming processes, the maximum hardness

attained was around 120 HB and a gradual decrease was

observed by increasing reheating durations in both measured

hardness and density values. The tensile properties

were also investigated, and the results were found

promising after the optimization of the forming pressure

and reheating duration except for the elongation values.