Steffen Wolf

Synthena (Switzerland)

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L. Claes

Universität Ulm

Lutz Krüger

TU Bergakademie Freiberg

Stefan Martin

TU Bergakademie Freiberg

Peter Augat

Berufsgenossenschaftliche Unfallklinik Murnau

Andreas Weiß

Catholic University of Eichstätt-Ingolstadt

Ulrich Martin

Charité - Universitätsmedizin Berlin

Andreas Jahn

MS-Schramberg (Germany)

A. G. Kovalev

Optolink (Russia)

M. Vanderkarr

Johnson & Johnson (United States)

Piotr R. Scheller

TU Bergakademie Freiberg

Cooperative Institutions

TU Bergakademie Freiberg

Universität Ulm

Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

Max-Planck-Institut für Nachhaltige Materialien

Institute of Metallurgy

VDEh-Betriebsforschungsinstitut

Jernkontoret (Sweden)

Chinese Society for Electrical Engineering

John Wiley & Sons (Germany)

Friedrich Schiller University Jena

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A Material Model for TRIP‐Steels and its Application to a CrMnNi Cast Alloy

steel research international (2011)

Stefan Prüger Meinhard Kuna Steffen Wolf Lutz Krüger

Abstract A material model is presented that accounts for strain rate dependent inelastic deformation and strain‐induced phase transformation in TRIP‐steels. Modifications for the kinetics equations of the strain‐induced phase transformation, introduced by Stringfellow, are proposed to overcome a drawback of Stringfellow's model. A parameter identification strategy that relies on Gauss‐Markov estimates is used to determine the model parameters from experimental data of a recently developed cast TRIP‐steel. Good agreement is observed between experimental results of the compression test and the corresponding finite element simulation employing the proposed model. This forms the basis for future applications of the material model in the design of composites and structures.

Basis (linear algebra)

Alloy steel

Experimental data

10.1002/srin.201100072

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Citations (17)

Pupils discovering materials at Technische Universität Bergakademie Freiberg

Advanced Engineering Materials (2007)

Steffen Wolf Sebastian Henkel Horst Biermann G. Sacher Tom Schöpe

10.1002/adem.200790024

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Citations (1)

Stress‐Temperature‐Transformation and Deformation‐Temperature‐Transformation Diagrams for an Austenitic CrMnNi as‐cast Steel

steel research international (2011)

A. G. Kovalev Andreas Jahn Andreas Weiß Steffen Wolf P. R. Scheller

Abstract Stress‐Temperature‐Transformation (STT) and Deformation‐Temperature‐Transformation (DTT) diagrams are well‐suited to characterize the TRIP (transformation‐induced plasticity) and TWIP (twinning‐induced plasticity) effect in steels. The triggering stresses for the deformation‐induced microstructure transformation processes, the characteristic temperatures, the yield stress and the strength of the steel are plotted in the STT diagram as functions of temperature. The elongation values of the austenite, the strain‐induced twins and martensite formations are shown in the DTT diagram. The microstructure evolution of a novel austenitic Cr‐Mn‐Ni (16%Cr, 6% Mn, 6% Ni) as‐cast steel during deformation was investigated at various temperatures using static tensile tests, optical microscopy and the magnetic scale for the detection of ferromagnetic phase fraction. At the temperatures above 250 °C the steel only deforms by glide deformation of the austenite. Strain‐induced twinning replaces the glide deformation at temperatures below 250 °C with increasing strain. Below 100 °C, the strain‐induced martensite formation becomes more pronounced. The kinetics of the α'‐martensite formation is described according to stress and deformation temperatures. The STT and DTT diagrams, enhanced with the kinetics of the martensite formation, are presented in this paper.

Twip

Diffusionless transformation

10.1002/srin.201100065

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Citations (26)

Effects of one-plane and two-plane external fixation on sheep osteotomy healing and complications

Clinical Biomechanics (2002)

Gert Krischak A. Janousek Steffen Wolf Peter Augat L. Kinzl

Biomechanics

Callus

10.1016/s0268-0033(02)00039-6

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Citations (43)

ESWL oder Ureteroskopie bei Kindern mit Nierensteinen?

Urologie Scan (2016)

Rohit Tejwani H H Wang Steffen Wolf

Fazit Mittlerweile werden Kinder mit Urolithiasis zunehmend häufiger endoskopisch behandelt, fassen die Autoren zusammen. Sie müssen allerdings bis 3 Monate nach der Intervention häufiger in der Klinik oder der Notaufnahme behandelt werden als Kinder nach ESWL. Umgekehrt ist bei Kindern nach ESWL häufiger eine Folgebehandlung notwendig, um Steinfreiheit zu erreichen.

10.1055/s-0042-118889

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Citations (0)

Shape manipulation of ion irradiated Ag nanoparticles embedded in lithium niobate

Nanotechnology (2016)

Steffen Wolf Jura Rensberg Andreas Johannes R. Thomae Frederick Smit

Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic 84Kr and 197Au ions, resulting in different electronic energy losses between 8.1 and 27.5 keV nm−1 in the top layer of the samples. Due to the high electronic energy losses of the irradiating ions, molten ion tracks are formed inside the lithium niobate in which the elongated Ag nanoparticles are formed. This process is strongly dependent on the initial particle size and leads to a broad aspect ratio distribution. Extinction spectra of the samples feature the extinction maximum with shoulders on either side. While the maximum is caused by numerous remaining spherical nanoparticles, the shoulders can be attributed to elongated particles. The latter could be verified by COMSOL simulations. The extinction spectra are thus a superposition of the spectra of all individual particles.

Extinction (optical mineralogy)

Particle (ecology)

10.1088/0957-4484/27/14/145202

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Citations (32)

Werkstoffverhalten einer TRIP/TWIP-fähigen CrMnNi-Stahlgusslegierung bis zu hohen Dehnraten*

Materials Testing (2010)

Lutz Krüger Steffen Wolf Stefan Martin M. Rüssel Ulrich Martin

Kurzfassung Das Fließspannungsverhalten einer hochlegierten metastabilen Stahlgusslegierung wurde in einem weiten Bereich der Dehnrate (4·10 −4 s −1 bis 2200 s −1 ) unter Zug- und Druckbeanspruchung untersucht. Dabei wurde ein ausgeprägter TRIP(TRansformation Induced Plasticity)-Effekt der austenitischen Legierung auf CrMnNi-Basis beobachtet, welcher zu hohen Festigkeiten und exzellenter Verformbarkeit führt. Bei Temperaturen oberhalb von 60°C bis 100°C zeigte sich zusätzlich eine mechanische Zwillingsbildung (TWIP- Effekt). Ein besonderes Augenmerk lag auf der Untersuchung der durch die mechanische Beanspruchung hervorgerufenen Mikrostrukturentwicklung. Es wurde festgestellt, dass erhöhte Beanspruchungsgeschwindigkeiten wesentlich das Werkstoffverhalten der untersuchten Legierungen beeinflussen. Mit steigender Dehnrate erfolgt eine Erwärmung der Probe, welche der Entstehung von α'-Martensit entgegenwirkt und so maßgeblich das Verfestigungsverhalten des Werkstoffes beeinflusst.

Twip

10.3139/120.110165

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Citations (7)

Improving Stochiometery and Processing of LSCF Oxygen Electrode for SOFC

Meeting abstracts/Meeting abstracts (Electrochemical Society. CD-ROM) (2009)

Asif Ansar Dennis Soysal Zeynep İlhan Steffen Wolf Nobert Wagner

Abstract not Available.

Clark electrode

10.1149/ma2009-02/12/1352

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Citations (0)

Biomechanical comparison of a 3.5 mm anterior locking plate to cannulated screws with anterior tension band wiring in comminuted patellar fractures

Injury (2020)

Ferdinand C. Wagner Mirjam Neumann Steffen Wolf Alexander Jonaszik Kaywan Izadpanah

Patella fracture

Tension band wiring

Cadaveric spasm

Osteosynthesis

Biomechanics

10.1016/j.injury.2020.03.030

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Citations (23)

Deformation Bands in High‐Alloy Austenitic 16Cr6Mn6Ni TRIP Steel: Phase Transformation and Its Consequences on Strain Hardening at Room Temperature

steel research international (2015)

Stefan Martin Steffen Wolf Sabine Decker Lutz Krüger Ulrich Martin

In this study, the formation of deformation bands during plastic deformation in austenite is analysed. The movement of (partial) dislocations on neighboring lattice planes formed pronounced deformation bands, which were identified as ϵ‐martensite if the stacking faults are predominantly aligned on every second {111} lattice plane. In these deformation bands, α′‐martensite nuclei are formed, severely fragmenting the mean free path of dislocations. The strain hardening is found to depend directly on the nucleation rate of α′‐martensite. The α′‐martensite nuclei represented effective barriers for (partial) dislocation movement in the deformation bands. On the basis of three different grain sizes, the strain‐hardening capability of the martensitic γ → ϵ → α′ phase transformation is analysed. Although the triggering stress for nucleation of α′‐martensite is influenced by grain size, the absolute value of the strain hardening due to α′‐martensite formation is the same. This is related to the fact that the continuous fragmentation of the dislocation mean free path is in the same order of magnitude for all grain sizes. Using a basic approach that treated the continuous reduction of the dislocation mean free path as a Hall–Petch‐like effect, comparable with strain hardening in TWIP steels, the contribution of the effect to the increasing strength in austenitic TRIP steels is estimated.

Hardening (computing)

Deformation bands

Diffusionless transformation

Strain hardening exponent

10.1002/srin.201500005

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Citations (68)