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[References: 12 tit.]

The paper studies the effect of the temperature of helical rolling, which creates nanoscale mesoscopic structural states in lattice curvature zones, on the low-temperature impact toughness of Ti-6Al-4V alloy. The polymorphic transformation temperature Tс = 950°C is shown to play the decisive role in this effect. The impact toughness is very high at helical rolling temperatures above Tс, while in the low-temperature range up to T = -70°C it decreases monotonically. This is a very important aspect of the technology. Starting from the helical rolling temperature T = 950°C, the toughness sharply decreases at T = -70°C. At T = 900°C, it decreases sharply already at T = -20°C. At T = 850°C, the level of the entire toughness curve of the alloy is low. The high level of impact toughness at T > Tс is found to be due to a two-stage transformation of the bcc β phase into a mixture of (α + β) phases. The first stage involves nonequilibrium microscopic decomposition into the α and β phases. At the second stage, the nonequilibrium β phase decomposes into (α + β) subbands in accordance with the interstitial structural states associated with lattice curvature. In helical rolling at T < Tс, the formation of martensite phases in the close-packed lattice of the α phase of titanium reduces its impact toughness. The fatigue life of Ti-6Al-4V alloy helically rolled at T = 1000°C remains unchanged.