LEZHNEV Sergey Karaganda State Industrial University

Spoluautoři VOLOKITINA Irina, NAIZABEKOV Abdrakhman, CHALAYA Oksana

The instability of the structure is one of the problems standing in the way of widespread use of submicrocrystalline (SMC) materials. In pure SMC metals there is a relatively low temperature of recrystallization and substantially nonuniform of grain growth at temperatures close to the temperature of recrystallization. Rapid grain growth during heating leads to loss of the unique physical and mechanical properties of the material. The purpose of this work was to investigate the influence of preliminary thermal treatment on the structure that is formed in copper at ECA-pressing and subsequent heat treatment. Microstructure of copper samples subjected ECA -pressing, change under the action simultaneous influence of two factors: the preliminary heat treatment and increasing the pressing temperature. Minimum average grain size obtained during pressing of alloy M1 is 0.6 microns. This grain size is obtained after quenching at 7000C and ECAP at room temperature and 6 cycles of deformation. The use of preliminary quenching provides a more fine-grained structure as well for the alloy M1 also to reduce hardness by 15%, which helps to reduce the pressing force on the first pass, from 620 to 510 MPa. The use of combined thermomechanical treatment on a "quenching at 7000C - ECAP low-tempered at 2000C" for the alloy M1 allows significantly improving the characteristics of copper and increases the resistance emergence and spread of cracks.

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