Suppression of trip effect in metastable steel by electrical current

Stolyarov, V. V.; Klyatskina, Elizaveta; Terentyev, V. F.

doi:10.22226/2410-3535-2016-4-355-359

Cited by 7 publications

(3 citation statements)

References 7 publications

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“…In Fig. 3 the engineering stress-strain curves in the temperature range of 20 -200°C are presented (for completeness, curve 5 is reproduced from our earlier publication [13]). At a test temperature of 20°C (curve 1), beyond the yield point, as in a previous report, weak deformation hardening is observed [12].…”

Section: Resultsmentioning

confidence: 99%

Temperature dependence of the TRIP effect in a metastable austenitic stainless steel

Stolyarov¹,

Padmanabhan²,

Terentyev³

2019

LOM

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The effect of test temperature in the range 20-400°C on mechanical properties under quasi-static tension and phase composition in metastable austenite-martensite TRIP steel in the form of a sheet of 0.3 mm thickness is investigated. Here strength and ductility increases are caused by austenite to martensite phase transformation. As supplied, the steel contained 65 % martensite and 35 % austenite. Due to tensile testing at room temperature, the amount of martensite increases to 84 %, which leads to high strength (1600 MPa) and a relative elongation to failure of 20 %. There is no neck formation. With an increase in test temperature from room temperature to 400°C, the strength characteristics, especially yield strength, sharply decreases to 700 MPa and below. At the same time, the elongation to failure decreases by an order of magnitude to 2 %. Above a test temperature of 100°C, deformation localization begins, the length of the yield plateau on the stress-strain curve decreases, and then disappears. X-ray structural analysis of the sample surface after tension showed that the volume fraction of martensite in the microstructure decreases from 84 % at 20°C to 42 % at 400°C. With an increase in temperature in the range of 20-400°C the influence of the TRIP effect on the mechanical properties of austenitic steel gradually decreases, and the direct transformation of austenite to martensite eventually changes to the reverse transformation of martensite to austenite. It is assumed that the embrittlement of steel with increasing temperature is associated with inhomogeneous martensite decomposition and precipitation of fine carbides at grain boundaries.

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Section: Resultsmentioning

confidence: 99%

Temperature dependence of the TRIP effect in a metastable austenitic stainless steel

Stolyarov¹,

Padmanabhan²,

Terentyev³

2019

LOM

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“…Однако в стали 316L было установлено, что ЭПЭ при растяжении приводит к охрупчиванию за счет двойникования в структуре [16]. Оказалось, что воздействие тока может стимулировать или подавлять фазовые превращения [17]. Этот аспект наиболее интересен в приложении к ТРИП сталям, в которых прямое мартенситное превращение аустенит -мартенсит индуцируется пластической деформацией.…”

Section: Introductionunclassified

Electroplastic effect at tension in TRIP steel

Stolyarov

2022

Izv. vysš. učebn. zaved., Čern. metall.

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The paper presents the results of a study of electroplastic effect in metastable high-alloyed austenitic-martensitic steel in strip form with the thickness of 0.3 mm during plastic deformation with current of different modes and regimes. Choice of the research material is due to manifestation of the TRIP effect in it, caused by martensitic transformation during deformation. The ratio of volume fractions of austenite and martensite in the steel before deformation was 50:50. Deformation behavior of the steel was studied by stress-strain curves and mechanical properties at room temperature in static tension with current by short single pulses of large density, as well as multipulse current with frequency of 1000 Hz and direct current. Microstructure in the initial, before tension, state was investigated by optical and transmission microscopy. It consists of large equiaxed grains of austenite and twinned martensite up to 80 µm in size. Phase composition of the steel before and after tension with and without current was studied by X-ray diffraction. Tensile deformation without current promotes martensitic transformation and increases the volume fraction of martensite from 50 to 82 %. The introduction of single current pulses does not influence the TRIP effect, causes power surges and confirms the occurrence of electroplastic effect. Current mode has a strong influence on manifestation of the TRIP effect, suppressing it at multipulse and direct current and causing a sharp decrease in tensile strength, yield stress, and elongation to failure. Tension with current stabilizes the austenite and reduces content of the formed martensite up to 72 % in multi-pulse mode and up to 50 % when using direct current.

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“…Qin et al [15] studied the role of different tilt GBs on MT in NiTi alloy during thermal cycling using MD method and concluded that some GBs retarded while the others promoted the martensite formation. There is also no general opinion about the effect of twin boundaries on MT [16,17] that can be responsible for the transformation induced plasticity effect [18].…”

Section: Introductionmentioning

confidence: 99%

Martensitic phase transformation in NiTi bi-crystals with symmetric ∑25 twist and tilt grain boundaries

Babicheva¹,

Gunderov²,

Stolyarov³

et al. 2018

LoM

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NiTi alloys attract a lot of attention of researchers for a number of reasons; among them are their practical importance and challenges for theoretical understanding. The most exciting feature of these alloys is the shape memory effect due to the martensitic transformation at temperatures close to the room temperature. There exist many factors affecting the transition temperatures in such materials, such as a deviation from stoichiometric composition, dislocation density, grain size, and the type of grain boundaries. The latter factor is one of the less explored, and we are aware of just a few studies in this direction. In the present work, molecular dynamics simulations are carried out to reveal the effect of symmetric tilt and twist grain boundaries in bi-crystals with nanosized grains on the forward and reversed martensitic transformations during cooling down from the austenite B2 phase and subsequent heating up from the martensite B19' phase. Phase composition, elastic strain components, relative change of volume, potential energy per atom, and shear stresses are calculated and analyzed as the functions of temperature. It is found that the type of grain boundaries in the bi-crystals strongly affects the transition temperatures. Start and finish temperatures of the forward and reverse martensitic transformations are much lower in the bi-crystal with twist grain boundaries as compared to that having tilt grain boundaries. Overall, the simulation results of this study are in a good qualitative agreement with the available experimental data. NiTi сплавы привлекают большое внимание исследователей по ряду причин; среди них их практическая ценность и сложность для теоретического понимания. Наиболее выдающаяся особенность таких сплавов это эффект памя-ти формы, который обусловлен мартенситным превращением, протекающим при температурах близких к комнат-ной. Существует множество факторов влияющих на температуру фазового перехода в этих материалах, например, отличие химического состава сплава от стехиометрического, плотность дислокаций, размер кристаллитов и тип границ зерен. Последний фактор, из перечисленных, наименее изучен, и мы осведомлены только о нескольких ра-ботах, посвященных этому вопросу. В данной работе проведено моделирование методом молекулярной динамики с целью изучения вопроса влияния симметричной границы наклона и кручения в нанокристаллических бикристал-лах на прямой и обратный мартенситные переходы при охлаждении с аустенитной B2 фазы и последующем нагреве с мартенситной B19' фазы. Определены и проанализированы фазовый состав, компоненты упругой деформации,

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Suppression of trip effect in metastable steel by electrical current

Cited by 7 publications

References 7 publications

Temperature dependence of the TRIP effect in a metastable austenitic stainless steel

Temperature dependence of the TRIP effect in a metastable austenitic stainless steel

Electroplastic effect at tension in TRIP steel

Martensitic phase transformation in NiTi bi-crystals with symmetric ∑25 twist and tilt grain boundaries

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