A basic approach for strain rate dependent energy conversion including heat transfer effects: An experimental and numerical study

Meyer, Lothar; Herzig, Norman; Halle, Thorsten; Hahn, F.; Krueger, Lothar; Staudhammer, K.P.

doi:10.1016/j.jmatprotec.2006.07.040

Cited by 35 publications

(12 citation statements)

References 16 publications

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“…Consequently adiabatic flow curves should be corrected to isothermal flow curves. The dependency of adiabatic heating should be included in the constitutive equations [19]. Self-heating is therefore a phenomenon that provokes a softening effect and reduces the level of work hardening for steel materials.…”

Section: Cold Deformation Domain (T=tmentioning

confidence: 99%

An experimental investigation of the behaviour of steels over large temperature and strain rate ranges

Hor

Morel

Lebrun

et al. 2013

International Journal of Mechanical Sciences

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. During forging and machining manufacturing processes, the material is subject to large strains at high strain rates which provoke local heating and microstructural changes. Modelling of these phenomena requires precise knowledge of the stress-strain constitutive equations for a large range of strains, strain rates and temperatures. An experimental study of the rheology of both hyper-and hypo-eutectoid steels (with different microstructures) over a temperature range from 20 1C to 1000 1C and with strain rates from 10 À2 to 10 5 s À1 has been undertaken. These tests were performed in compression on cylindrical specimens and in shear using hat-shaped specimens. Both a GLEEBLE 3500 thermomechanical testing machine and a Split-Hopkinson Pressure Bar apparatus were used. From these tests, three deformation domains have been identified as a function of the material behaviour and of the changes in the deformed microstructure. Each domain was characterized by its behaviour, including the competition between hardening and softening, strain rate sensitivity on the flow stress and the softening phenomenon (i.e. recrystallisation or recovery, etc.). Finally, based on thermodynamical considerations, the conditions of thermoplastic instability (i.e. shear bands, twinning, heterogeneities, etc.) and microstructural changes are highlighted using process maps of the dissipated power repartition.

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Section: Cold Deformation Domain (T=tmentioning

confidence: 99%

An experimental investigation of the behaviour of steels over large temperature and strain rate ranges

Hor

Morel

Lebrun

et al. 2013

International Journal of Mechanical Sciences

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“…An experimental noise is added to an analytical temperature signal θ an defined as: (32) where A and τ are the temperature variation parameters. Here, A = 0.2 • C and τ = 10 s have been chosen, the standard deviation of the noise being of 5.7.10 −4 • C.…”

Section: Time Differential Calculationmentioning

confidence: 99%

“…Usually, E i st is thus estimated by simultaneously measuring the mechanical work and dissipative energy W i m and E i d 1 . If many experimental data concerning the macroscopic stored energy are available in monotonic compression and tension at various strain rates [25,[29][30][31][32][33][34], fewer experimental energy balances have been achieved in cyclic loading [16,21,27,35,36].…”

Section: Introductionmentioning

confidence: 99%

Experimental Energy Balance During the First Cycles of Cyclically Loaded Specimens Under the Conventional Yield Stress

2010

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This paper, as an extension of Maquin and Pierron (Mech Mater 41 (8): [928][929][930][931][932][933][934][935][936][937][938][939][940][941][942] 2009), presents an experimental procedure developed to macroscopically estimate the energy balance during the very first cycles of a uniaxially loaded metallic specimen at low stress levels. This energy balance is performed by simultaneously measuring the plastic input energy using a load cell and a strain gauge, and the dissipative energy using the temperature field provided by an infrared camera. Some experimental limitations led to restrain the present procedure to positive stress ratios, and to complement this energy balance by a second measurement while the material plastic work per cycle is negligible compared to the dissipative energy. Some results obtained on a cold rolled low carbon steel specimen are presented. First, a sensitivity study is undertaken to precisely determine the detection threshold on both thermal and plastic energies. Then, after having verified the homogeneity of the dissipative source fields, energy balances have been performed at different stress levels. It was thus confirmed that the slow variations of the dissipative sources occurring during the first cycles are due to micro-plastic adaptation, and that the dissipative N. Connesson (B) · F. Maquin · F. Pierron (SEM Member) sources remaining after some hundreds of cycles are due to viscoelastic (internal friction) phenomena. This procedure provides a better understanding of dissipation based approaches to fatigue found in the literature and an advanced tool to study viscoelastic phenomena in uniaxial loading.

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“…By applying Eq. (4) it is possible to compute an approximate temperature rise DT in the specimen [43][44][45]:…”

Section: Resultsmentioning

confidence: 99%

High strain rate behavior, transformation-induced plasticity and fracture toughness characterization of cast and additionally tempered Fe85Cr4Mo8V2C1 alloy manufactured using a rapid solidification technique

et al. 2012

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This study focuses on the characterization of the microstructures of an FeCrMoVC alloy in two states (an as-cast and a heat-treated state) as well as the compressive strain rate-dependent material and fracture toughness behavior. Both microstructures consist of martensite, retained austenite and complex carbides. Tempering results in a transformation of retained austenite into martensite, the precipitation of fine alloy carbides, and diffusion processes. High yield stresses, flow and ultimate compressive strength values at a relatively good deformability were measured. The yield and flow stresses at the onset of deformation are higher for the heat-treated state due to higher martensitic phase fractions and fine precipitations of alloy carbides respectively. Compressive deformation causes a straininduced transformation of retained austenite to a 0 -martensite. Hence, both high-strength alloys are TRIP-assisted steels (TRansformation-Induced Plasticity). However, the martensitic transformation is more pronounced in the as-cast state due to higher phase fractions of retained austenite already in the initial state. Examinations of strained microstructures showed decreased crystallite sizes with increasing deformation. It is assumed that, during plastic deformation, the amount of low angle grain boundaries increases while the incremental formation of a 0 -martensite leads to decreased crystallite size. In general, lower microstrains were determined in the heat-treated state as a consequence of stress relaxation during tempering. In comparison to commercially available tool steels, the determined fracture toughness K Ic of both variants revealed relatively high fracture toughness values. It was found that the lower shelf of K Ic is already reached at room temperature. Higher loading rates _ K resulted in lower dynamic fracture toughness K Id values. Notch fracture toughness K A measurements indicate that the critical notch tip radii of the examined materials are slightly smaller than 0.09 mm.

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A basic approach for strain rate dependent energy conversion including heat transfer effects: An experimental and numerical study

Cited by 35 publications

References 16 publications

An experimental investigation of the behaviour of steels over large temperature and strain rate ranges

An experimental investigation of the behaviour of steels over large temperature and strain rate ranges

Experimental Energy Balance During the First Cycles of Cyclically Loaded Specimens Under the Conventional Yield Stress

High strain rate behavior, transformation-induced plasticity and fracture toughness characterization of cast and additionally tempered Fe85Cr4Mo8V2C1 alloy manufactured using a rapid solidification technique

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