Yield stress, polymorphic transformation, and spall fracture of shock-loaded iron in various structural states and at various temperatures

Abstract

Delayed failure in a shock-loaded silicon carbideThe response of polycrystalline 99.5% pure iron was studied in a series of planar impact experiments, with samples of different thickness having an initial temperature that ranged between 300 and 1233 K. The free surface velocity histories of the shocked samples were recorded in the course of the experiments. Almost all recorded histories are characterized by a three-wave structure containing an elastic precursor P el and two plastic, P1 and P2, waves. It was found that at 300, 900, and 1039 K (some 5 K away from iron's Curie point), the decay of the P el wave with propagation distance is characterized by two different regimes; a fast one that corresponds to plastic strain rates above $10 5 s À1 and a slower one at lower strain rates. Since the shear stress at which the change-over takes place is very close to the Peierls stress of iron, we assume that above this stress the decay is governed by the phonon-damped over-barrier dislocation motion, while below it, the thermally activated generation and motion of the dislocation kinks is the governing mechanism. Based on the parameters of the P1 and P2 waves, both the initial and the maximum rates of the a ! e transformation in iron have been estimated. The results indicate that the approach to the Curie point is associated with a substantial, by 2-3 times, increase of the transformation rate. V C 2015 AIP Publishing LLC. [http://dx.

Characterisation of high rate plasticity in the uniaxial deformation of high purity copper at elevated temperatures

“…We find a significant difference in the temperature responses of the thermally activated and phonon drag regimes. Whilst the pinning regime thermally softens, in a purely viscous regime the specimen strength is predicted to increase approximately in proportion to the absolute temperature (Grunschel et al, 2012;Gurrutxaga-Lerma et al, 2017;Kanel, 2014;Kanel et al, 2001;Kuksin and Yanilkin, 2013;Zaretsky and Kanel, 2015). The transition is shown in Figure 2, that shows a sketch of the flow stress as a function of rate for two different temperatures as specimens enter a phonon limited regime.…”

Высокоскоростная Деформация И Разрушение Стали 15Х2НМФА Под Действием Ударной Нагрузки При Нормальной И Повышенной Температурах

“…На рис. 13 результаты измерений динамического предела упругости стали 15Х2НМФА при комнатной температуре сопоставляется с полученными ранее [24][25][26][27][28] аналогичными данными для железа. В основном эти данные в пределах разброса совпадают.…”

Temperature-dependent void nucleation and growth in single-crystal and nanocrystalline iron at extreme strain rates: atomistic insights

“…Numerous studies have explored dynamic metal fracture under different strain rates [1,2]. For instance, Zaretsky et al [3] examined the dynamic response of polycrystalline iron at varying initial temperatures and a strain rate of 10 5 s −1 , analyzing temperature effects. Remington et al [4] investigated grain size impact on spalling strength at strain rates of 10 6 to 10 7 s −1 , revealing grain boundaries' role in void nucleation.…”