Том 8, Выпуск 4s, Декабрь 2018

The IPSM building in Ufa used for research on all aspects of superplastic flow and superplastic forming

Fundamental and applied researches in the field of superplasticity and related phenomena have always been extensively carried out at the Institute for Metals Superplasticity Problems of the Russian Academy of Sciences (IMSP RAS)

Miniaturised samples from AX52 magnesium alloy were tested in tension in a wide strain rates region. Parameters of the thermally activated mechanisms were estimated and discussed.

To bridge the gap between the ideal case of steady-state for superplasticity and the realistic case of deviation from this, the parameters of constitutive relationship should include the instantaneous microstructure and consider effective stress for deformation instead of applied stress

ECAP-processed Zn-22Al and Zn-0.3Al alloys were subjected to long-term natural aging up to 1100 days to evaluate the effect of long-term natural aging on their microstructures and superplastic behaviors. Decrease in the maximum elongation of Zn-22Al alloy is quite low comparing to its ECAP-processed condition while Zn-0.3Al alloy loses more than half of its superplastic elongation at the end of the natural aging.

Two deformation temperatures and two strain rates were selected upon the initial measurement of thermal stability and dependence of m-parameter on strain rate and temperature. Evolution of m-parameter during the tensile tests was measured thank to the periodical switching of the strain rate.

Superplastic properties of titanium alloys with coarse-grained (CG) and ultrafine-frained (UFG) structure

The studied Al7075 alloy modified by the addition of Sc and Zr processed by 6 passes of ECAP at 120 °C exhibited „low temperature” superplasticity. The maximum elongation of 340 % was achieved at the straining temperature of 200 °C with parameter m = 0.3.

Температурные зависимости относительного удлинения, полученные для исследуемых сплавов.

Проведен сравнительный анализ микроструктуры и характеристик сверхпластичности сплава 1570C, подвергнутого равноканальному угловому прессованию при температуре 325oC и последующей теплой прокатке при той же температуре и холодной прокатке при комнатной температуре с суммарным обжатием до 86 и 80%, соответственно.

The novel Ti-21Al-18Nb-1Mo-2V-0.3Si intermetallic alloy with fine-grained structure exhibited superplastic behavior in the temperature range of 875-1000C with the highest elongation of 958% at 960C. Microstructure analysis revealed that under the optimum superplastic conditions the B2/Alpha2 phase boundary sliding played an important role during superplastic deformation of the Ti2AlNb-based alloy. At 960C, the deformation induced grain growth along with the signs of extensive grain rotation and the O→B2→Alpha2 phase transformations were also observed.