PSI - Issue 65

I.S. Kamantsev et al. / Procedia Structural Integrity 65 (2024) 109–113 I.S. Kamantsev et al. / Structural Integrity Procedia 00 (2024) 000–000

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From Table 2 it is evident that at annealing temperatures of 300 and 350 °C a sufficiently large number of elongated grains oriented in the rolling direction are observed, and grains close in shape to equiaxed grains also begin to appear. A change in grain elongation compared to the deformed state indicates the onset of recrystallization processes in the material. At an annealing temperature of 370 °C, grain elongation continues to decrease, and the number of grains close to equiaxed grains increases. A further increase in the annealing temperature to 400, 450 and 495 °C contributes to a decrease in grains with an elongated shape, respectively, the grain form factor value tends to 1. Despite a large number of equiaxed grains, the form factor values of 1.15 indicate ongoing processes of primary recrystallization. It is worth noting that at a recrystallization temperature above 400 °C, the changes in the form factor are not as intense as at lower temperatures, and they are also practically independent of the holding time of the samples at a given temperature. This cannot be said for temperatures below 400 °C. The lower the annealing temperature, the more visible is the difference in the form factor values, and therefore the elongation of the grains after deformation. Apparently, an increase in the holding time allows achieving the formation of an equiaxed grain in the aluminum alloy 2024 at lower temperatures. The microhardness of the aluminum alloy 2024 increases monotonically depending on the annealing temperature, while the holding time does not significantly affect its values. Thus, annealing at temperatures above 400 °C, while the holding time in the furnace (1 or 2 hours) no longer affects the grain form factor, is most preferable, since an equiaxed structure with increased microhardness values is formed in the material, which is due to the processes of precipitation of S and θ phases in the aluminum alloy 2024 - Elagin et al. (1974).

4. Conclusions

It is shown that at annealing temperatures above 400 °C, the holding time has virtually no effect on the grain form factor values of the aluminum alloy 2024. At annealing temperatures above 400 °C, a uniform structure with increased hardness values relative to the plastically deformed and initial state of the studied alloy is formed. It was also found that an increase in the holding time during recrystallization annealing allows for the formation of an equiaxed grain in the aluminum alloy 2024 at lower temperatures.

References

Antipov, V., Klochkova, Y., Romanenko, V., 2017. Modern aluminum and aluminum-lithium alloys. Aviation materials and technologies, No. S. P. 195-211. Shveikin, V., Kamantsev, I., Pugacheva, N., Zadvorkin, S., Senaeva, E., Razinkin, A., Maltseva, T., Kalinina, N., Bykova, T., Skorynina, P., Putilova, E., 2023. Application of Microindentation to the Evaluation of Strain Distribution over the Section of Extruded Aluminum Alloy Bars. Diagnostics, Resource and Mechanics of materials and structures 6, 45-64. Berezovskaya, V., Ishina, E., Ozerets, N., 2016. State diagrams of ternary systems. Publishing house of the Ural University, Ekaterinburg, pp. 120. Elagin, V., Livanov, V., 1974. Aluminum alloys. Structure and properties of semi-finished products from aluminum alloys. reference book, Metallurgy, Moscow, pp. 432. Filippov, M., Baraz, V., Gervasyev, M., 2013. Methodology for selecting metal alloys and strengthening technologies II, Publishing house of the Ural University, Yekaterinburg pp. 236. Kolachev, B., Elagin, V., Livanov, V., 1999. Metallurgy and heat treatment of non-ferrous metals and alloys, MISIS, Moscow, pp. 416. Maltseva, T., Ozerets, N., Levina, A., Ishina, E., 2019. Non-ferrous metals and alloys, Ural University Publishing House, Ekaterinburg, pp. 176. State standard 5639-82.