Project Proposal 20-22474J [601713]

Final
Project Proposal 20-22474J
Part A – Basic Info
The project budget is included in the Full version of a project proposal. Foreign reviewers do not evaluate financial part of
project proposals.
In accordance with the requirements listed in tender documentation, the maximum length of a project description is limited
to 10 pages size A4.
Registration No. 20-22474J
Starting Date 2020/01/01 Duration (years) 3
Project Title in Czech Výzkum termomechanického zpracování středně manganových ocelí během inkrementálního
kosého válcování
Project Title in English Fundamental research on thermomechanical treatment of medium-manganese steels during
helical rolling process
Main Panel P107 – Metallic materials – preparation and properties
Keywords in Czech vysokopevné oceli;TRIP efekt;inrekrementální tváření;kosé válcování
Keywords in English high-strength steels;TRIP effect;incremental forming;helical rolling
Applicant and Organisation
Name and Surname Dr. Ing. Hana Jirková Ph.D.
ORCID 0000-0003-4311-7797
SCOPUS ID 35772537700 Researcher ID A-5581-2012
Organisation University of West Bohemia in Pilsen, Faculty of Mechanical Engineering
Address Univerzitní 8,
Foreign Applicant
Reg. čís. zahr. části RA 3422
Name and Surname Anja Rautenstrauch
Organisation Chemnitz University of Technology, Institute for Machine Tools and Production Processes;
Professorship for Forming and Joining (UFF)
GRIS ORBEON 1.3.3.2-SNAPSHOT 1 / 17

Project Proposal 20-22474J
Abstract in English The project will focus on the thermomechanical processing of medium manganese high-
strength steels with a C content of approx. 0.2% using incremental rolling with the assistance of
FEM simulations. With helical rolling of bars, the insertion of deformation in very small steps
makes it possible to reduce the diameter from 30 to 12 mm even for high-strength steels. After
testing the parameters of forming and intercritical annealing, the influence of processing
parameters on the development of the multiphase structure and the determination of critical
processing conditions will be defined. In addition to other hardening mechanisms, the
mechanical properties will be improved by a combination of TRIP and TWIP effect, which will be
supported by multiple combinations of Mn and Al. In addition to the detailed investigation of
phase transformations, attention will be paid to the description of the steel formability. The
accurate choice of processing parameters will result in obtaining the desired multiphase
structures and achieving excellent mechanical properties including high ductility.
Project Aims in
EnglishThe aim of the project is to describe the behavior of medium manganese high-strength steels
during thermomechanical processing by incremental helical rolling with support by FEM
simulation and optimization of forming parameters and heat treatment in order to obtain
excellent mechanical properties.
CEP Classification
OECD Classification
Mechanical engineering – Materials engineering
Priorities enrollment
It may be suspected, that the results will contribute to the knowledge on following field(s) of National priorities of oriented
research, experimental development and innovations:
To improve economy, efficiency and adaptability in industries to empower global competitiveness in this area – Advanced
materials for the competitiveness
Organisation – Part D2 – Bibliography
Name and Surname Dr. Ing. Hana Jirková Ph.D.
Organisation University of West Bohemia in Pilsen, Faculty of Mechanical Engineering
Full bibliographic data regarding the most important results of scientific and research activity as
defined in the currently valid Methodology for Evaluating the Results of Research and Development
2 / 17 GRIS ORBEON 1.3.3.2-SNAPSHOT

Project Proposal 20-22474J
Result type
codeDatabase Citations Impact
factor
Result Contribution towards the publication
1JIRKOVÁ, H. Vliv termomechanického zpracování s inkrementálními
deformacemi na vlastnosti TRIP ocelí (The Influence of
Thermomechanical Treatment of TRIP Steel on its Final Microstructure). 1.
Edition. Praha : Grada Publishing, 2012, 158 p. ISBN: 978-80-247-4292-2 B Other 0
2JIRKOVÁ, H., KUČEROVÁ, L., MAŠEK, B. Effect of Quenching and
Partitioning Temperatures in the Q-P Process on the Properties of AHSS
with Various Amounts of Manganese and Silicon. Materials Science
Forum, 2012, Vol. 706-709, p. 2734-2739. ISSN: 0255-5476Jsc WOS 21 0.000
Scopus – 28
3JIRKOVÁ, H., JENÍČEK, Š., KUČEROVÁ, L., KURKA, P. High-strength
steel components produced by hot metal gas forming. MATERIALS
SCIENCE AND TECHNOLOGY, 2018, p. 1-9. ISSN: 0267-0836Jimp WOS 0 1.803
4JIRKOVÁ, H., MAŠEK, B., WAGNER, M. F., LANGMAJEROVÁ, D.,
KUČEROVÁ, L., TREML, R., KIENER, D. Influence of Metastable
Retained Austenite on Macro and Micromechanical Properties of Steel
Processed by the Q-P Process. Journal of Alloys and Compounds, 2014,
Vol. 615, No. 1, p. 163-168. ISSN: 0925-8388 Jimp WOS 20 3.779
Scopus – 31
5MAŠEK, B., JIRKOVÁ, H., RONEŠOVÁ, A., JENÍČEK, Š., ŠTÁDLER, C.
Method of Achieving Trip Microstructure in Steels by Means of
Deformation Heat. US 8,940,111 B2, Alexandria, Virginia, USA, 2015. P Other 0
Patent USA
Total number of results defined in the Methodology for Evaluating for Results of Research and
Development for last 5 years (according to RIV)
J – Article in professional journal, impacted 21
J – Article in professional journal, included in Scopus database 12
J – Article others 5
B – Scholar book/monograph 0
C – Chapter in scholar book/monograph 1
D – Article in conference proceedings 35
P – patent 18
F – Utility or industrial design 1
Z – Pilot run, verified technology, varienty, breed 2
G – Prototype, functional sample 1
H – Result implemented by funding provider (legislation, norms, strategic documents, policy recommendations,
etc.)0
L – Specializes map 0
N – Certified methodology and procedure 0
R – Software 0
V – Research report containing information classified pursuant to special legislation 0
Total number of citations, including autocitations, and a H-index (according to Web of Science)
Total number of citations, of all of the scientific work
according to244
Used methodology and total number of citation "by
used Methodology"Scopus – 11
H-index according to Web o Science 9.00imp
sc
ost
GRIS ORBEON 1.3.3.2-SNAPSHOT 3 / 17

Czech Science Foundation – Part D1
Applicant: Dr.-Ing. Hana Jirková, Ph.D.
Name: Hana Maiden name: Staňková
Surname: Jirková
Birthday: 10. 8. 1980 Nationality: Czech
Phone: +420 776 134549 Skype: Hanka_skype
Residence: Kotíkovská 1628/13, Pilsen
Czech Republic e-mail: hstankov@rti.zcu.cz

Education:
2005 – 2008
PhD. Study – Materials Science, Chemnitz University of Technology, Faculty of
Mechanical Engineering, Chair of Materials and Impact Engineering, Chemnitz,
Germany
2003 – 2008 PhD. Study – Materials Science, The University of West Bohemia in Pilsen, Faculty
of Mechanical Engineering, Czech Republic
1998 – 2003 University of West Bohemia in Pilsen, Faculty of Mechanical Engineering, Czech
Republic, Field of study: Materials Science and Metallurgy
Work experiences:
04/2006 –
present
The University of West Bohemia in Pilsen
07/2017-present: Regional Technological Institute: researcher
04/2006–06/2017: Research Centre of Forming Technology: research
administration manager
 coordination of research projects
 research and design of progressive types of AHS steels
 development and optimisation of innovative heat and thermomechanical treatments
 semi-solid processing and unconventional metal forming
 material-technological modelling
 metallographic analysis
09/2014-
10/2017  maternity leave
09/2002-
06/2003 TU Chemnitz, Faculty of Mechanical Engineering – scientific assistant:
 metallography
 incremental metal forming
 thermomechanical and heat treatment of high strength steels
03/2004 –
08/2004 Comtes FHT, Pilsen – work on diploma work
 metallography, thermomechanical and heat treatment
Stay abroad:
2002 Nordmetall GmbH, Chemnitz, Germany – Program Leonardo da Vinci
03/2004 –
07/2014 Chemnitz University of Technology, Faculty of Mechanical Engineering, Chair of
Materials and Impact Engineering, Germany:
 Study and Research Assistantship Program (03/2004-08/2004)
 Sokrates Erasmus Program (09/2004-08/2005)
 Georgius-Agricola Scholarship (09/2005-2/2005)
 Edgar-Heinemann Scholarship (01/2006-12/2006)

4 / 17 GRIS ORBEON 1.3.3.2-SNAPSHOT

Collaborations on selected research projects in last 5 years:
2012 – 2014

2012 – 2015

2015 – 2020
2017 – 2019

2019 – 2022 Effect of Forming in Semi-Solid State on Evolution of Microstructure of Powder
Metallurgy Steels (GA ČR P107/12/2600)
Innovation and Development of New Thermo-mechanical and Heat Treatment
Processes of Die Forgings by the Transfer of Findings Obtained from Material-
technological Modelling (TAČR TA02010390)
Development of the Regional Technological Institute (L01502)
Systematic Applied Research of Material Properties of Martensitic Steel W-Nr.
1.2709 Produced by 3D Printing Using DMLS Technology with the Application of
Research Results in Practice (TJ01000161)
Research of Additive Technologies for Future Use in Engineering Practice
(CZ.02.1.01/0.0/0.0/18_069/0010040)
Investigator or co-investigator:
2012 – 2014

2015 – 2017
2017 – 2018

2017 – 2019

2019 – 2021 Influence of a Structure Modification on Mechanical Properties of AHS Steels
(GA ČR P107/12/P960)
Semi-solid Processing and New Structures without Carbide Net (SGS-2015-028)
TRIPIAL TRansformation Induced Plasticity Isothermal Annealing Less (subproject
TG02010011-06)
Improvement of Properties and Complex Characterization of New Generat ion
Fe-Al-O Based Oxide Precipitation Hardened Steels (GA ČR 17-01641S)
Determination of the Principles and Processes Taking Place During the Stabilization
Annealing of Austenitic Stainless Steels Used in Nuclear Power (TJ02000274)
5 important results:
 JIRKOVÁ, H., RUBEŠOVÁ, K., KONOPÍK, P., OPATOVÁ, K. Effect of the Parameters of Semi-
Solid Processing on the Elimination of Sharp-Edged Primary Chromium Carbides from Tool Steel.
METALS, 2018, Vol. 8, No. 9, p. 1-15. ISSN: 2075-4701
 MAŠEK, B., JIRKOVÁ, H., RONEŠOVÁ, A., JENÍČEK, Š., ŠTÁDLER, C. Method of Achieving Trip
Microstructure in Steels by Means of Deformation Heat. US 8,940,111 B2, Alexandria, Virginia,
USA, 2015
 JIRKOVÁ, H., JENÍČEK, Š., KUČEROVÁ, L., KURKA, P. High-strength Steel Components
Produced by Hot Metal Gas Forming. Materials Science and Technology, 2019, p. 1-9. ISSN:
0267-0836
 JIRKOVÁ, H., MAŠEK, B., WAGNER, M. F., LANGMAJEROVÁ, D., KUČEROVÁ, L., TREML, R.,
KIENER, D. Influence of Metastable Retained Austenite on Macro and Micromechanical Properties
of Steel Processed by the Q-P Process. Journal of Alloys and Compounds, 2014, Vol. 615, No. 1,
p. 163-168. ISSN: 0925-8388
 JIRKOVÁ, H. Vliv termomechanického zpracování s inkrementálními deformacemi na vlastnosti
TRIP ocelí (The Influence of Thermomechanical Treatment of TRIP Steel on its Final
Microstructure). 1. Edition. Praha: Grada Publishing, 2012, 158 s. ISBN: 978-80-247-4292-2
Publications activities: Awards and other important results:
 90 publication on WOS
(195 in total)
 1 book
 co-author of 13 CZ patents
 co-author of 5 US patens
 6 verified technologies
 3 utility design
 4 functional samples
 H-index 9
 ResearcherID: A-5581-2012  Rector´s Award, University of West Bohemia – 15. 11. 2006
 Sachsen Award for Forming Technology (Umbach Preis) –
2008 Germany
 Edgar-Heinemann Award – 2009 Germany
 Festo Award for Young Researchers and Scientists – 2009
Austria
 Steel Innovation Award: finalist (from 644 projects) –
certificate of merit for “exemplary high innovative potential
with diverse usability of steel materials“– 2009 Germany
 Rector's Certificate of Merit, University of West Bohemia –
18. 11. 2009
GRIS ORBEON 1.3.3.2-SNAPSHOT 5 / 17

– 1 –
Dr.-Ing. Dipl.-Wi.-Ing.

Anja Rautenstrauch
Research associate on TU Chemnitz, Institute of Machine Tools and Production Processes IWP;
Professorship of Forming and Joining UFF

Date of birth 12.04.1979
Place of birth Meissen, Saxony, Germany
Marital status in a partnership , two children
Address Technische Universität Chemnitz
Fakultät für Maschinenbau
Professur Umformendes Formgeben und Fügen
Reichenhainer Straße 70 / M -Bau
09126 Chemnitz/Germany
Phon +49 371 531 37327
E-Mail: anja.rautenstrauch@mb.tu -chemnitz.de
EDUCATION
2009 – 2016 Doctorate (Dr. -Ing.) Thesis: „Process design methodology to meet the requirements
of tailored structural parts “
Chemnitz University of Technology
2006 Graduate Industrial Engineer
(Dipl.- Wi.-Ing)
TU Bergakademie Freiberg, Germany
WORK EXPERIENCE
07/2006 –
02/2008 Research associate
Technical University of Berlin, Institute for Machine Tools and Industrial Production
03/2008 Project coordinator
Mechanical Engineering Network Saxony VEMAS, Chemnitz
04/2008 –
07/2018 Research associate, Project coordinator
Technical University of Chemnitz, Professorship Forming and Joining
12/2009 –
08/2016 Research associate
Fraunhofer Institute for Machine Tools and Forming Technology, Chemnitz
08/2018 –
10/2018 Research associate
Fraunhofer Gesellschaft
11/2018 –
01/2019 Research associate
Ammer, Quick und Partner GmbH
Since 02/2019 Research associate, Project coordinator
Technical University of Chemnitz, Professorship Forming and Joining
PUBLICATIONS
[1] Göschel, A.; Kunke, A.; Schönherr, J.; Rautenstrauch, A.: Design of Process Chain for Hot
Neugebauer, R; Lachmann, L.; Schönherr, J.; Rautenstrauch, A.: Anforderungen generieren fertigungstechnische Innovationen – Studie zur Halbwarm- Blechumformung von hochfesten
Stahlwerkstoffe. ZWF – Zeitschrift für wirtschaftlichen Fabrikbetrieb 104, 9/2009, S. 725 – 729
[2] Göschel, A.; Kunke, A.; Schönherr, J.; Rautenstrauch, A.: Design of Process Chain for Hot Forming of High Strength Steels – State of the Art and Future Challenges. In: International Conference on
Competitive Manufacturing 2010, Stellenbosch, S . 141 – 146
[3] Neugebauer, R.; Schieck, F.; Rautenstrauch, A.; Bach, M.: Gezieltes Temperaturmanagement bei der werkzeuggebundenen und der inkrementellen Formgebung in der Blechwarmumformung zur
6 / 17 GRIS ORBEON 1.3.3.2-SNAPSHOT

– 2 –
Einstellung gradierter Bauteileigenschaften. In: Neugebauer, R. (Hrsg.): Energieeffiziente Produkt –
und Prozessinnovationen in der Produktionstechnik; Zwickau: Verlag Wissenschaftliche Scripten,
2010, S. 769 – 788
[4] Neugebauer, R.; Schieck, F.; Rautenstrauch, A.: Process design of press hardening with gradient
material property influence. In: 14th International Conference on Material Forming – ESAFORM, 27th –
29th April 2011, Belfast/Great Britain, pp 1562 – 1567.
[5] Neugebauer, R.; Göschel, A.; Schieck, F.; Rautenstrauch, A.; Mosel, A.; Cai, H.: Enhancement of
process stabili ty and part quality for the press hardening of sheet metal, tubes and profiles. In: 3rd
International Conference on Hot Sheet Metal Forming of High- Performance Steel, 13th- 16th June
2011, Kassel. Auerbach: Verlag Wissenschaftliche Scripten, 2011, S. 229 – 236.
[6] Neugebauer, R.; Rautenstrauch, A.; Meza- García, E.: Influence of the alloying elements on phase
transitions of high strength steels. In: Advanced Materials Research; Materials Processing
Technology, 2011, Band 337, S. 358 – 362.
[7] Neugebauer, R.; Göschel, A.; Rautenstrauch, A.; Meza -García, E.: Influence of the steel alloy
composition on phase transitions and its applicability to hot forming process. In: Steel Research
International, Special Issue: ICTP 2011, International Conference on Technology of Pl asticity, Aachen,
Germany, 2011, pp 429 – 434.
[8] Neugebauer, R.; Schieck, F.; Rautenstrauch, A.; Bach, M.: Hot sheet metal forming the formulation of
graded component characteristics based on strategic temperature management for tool -based and
incremental forming operations. In: CIRP Journal of Manufacturing Science and Technology 4 (2011)
pp. 180 – 188, https://doi.org/10.1016/j.cirpj.2011.06.010
[9] Neugebauer, R.; Schieck, F.; Polster, S.; Mosel, A.; Rautenstrauch, A.; Schönherr, J.; Pierschel, N.:
Press harde ning – An innovative and challenging technology. In: 3rd International Lower Silesia –
Saxony Conference Advanced Metal Forming Processes in Automotive Industry, AutoMetF -orm 2012,
14. – 16. Mai 2012, Wrocaw, 2012, S. 45 – 55
[10] Neugebauer, R.; Schieck, F.; P olster, S.; Mosel, A.; Rautenstrauch, A.; Schönherr, J.; Pierschel, N.:
Press hardening – An innovative and challenging technology. In: Archives of Civil and Mechanical
Engineering 12 (2012), S. 113 – 118, https://doi.org/10.1016/j.acme.2012.04.013
[11] Meza -García, E.; Mosel, A.; Shchus, Y.; Rautenstrauch, A.; Lachmann, L.; Schieck, F.; Drossel, W. –
G.: Design of heat treatment processes for a tailored set of properties on 22MnB5 steel alloy sheets –
Simulation and Experiments. In: „4th International Conference on Hot Sheet Metal Forming of High
Performanc e Steel”, CHS2- 2013, 09. -12.06. 2013, Lulea, Sweden. Auerbach: Verlag
Wissenschaftliche Scripten, 2013, S. 337 – 344.
[12] Meza -Garcia, E.; Mosel, A.; Pierschel, N.; Polster, S.; Rautenstrauch, A.: Partielles Presshär ten –
Grundlagenuntersuchungen zur Prozess – und Werkzeuggestaltung, In: Proceedings of 3rd
International Colloquium of the Cluster of Excellence eniPROD; 08. – 09.04.2014, Chemnitz; Verlag
Wissenschaftliche Scripten, 2014, S. 277 – 294
[13] Meza García, E., Rautenstrauch, A.; Kräusel, V.; Landgrebe, D.: Press hardening of a martensitic stainless steel sheet alloy for manufacturing a side sill demonstrator with tailored properties. In: „5th
International Conference on Hot Sheet Metal Forming of High Performance Steel”, CHS2- 2015,
Toronto. Auerbach: Verlag Wissenschaftliche Scripten, 2015, pp. 765 – 773, 2015. – ISBN 987 -3-
95735- 023-7
[14] Meza García, E., Rautenstrauch, A.; Landgrebe, D.: Tailoring of mechanical properties of a side sill part made of martensitic stain less steel by press hardening 19th International ESAFORM Conference
on Material Forming – ESAFORM 27th- 29th April 2016, Nantes, France, AIP Conference Proceedings,
Volume 1769, 19 October 2016, Article number 130015
[15] Meza -García, E. ; Rautenstrauch, A.; Leon hardt, A.; Kräusel, V.; Landgrebe, D.: Forming with
Thermomechanical Treatment for Manufacturing a Side Sill Demonstrator of AA6082 Aluminium Sheet
Alloy. 6th International Conference Hot Sheet Metal Forming of High Performance Steel CHS², 04. –
07.06.2017, Atlanta/USA, S. 691 – 698. ISBN/ISSN: 978 -1-935117- 66-7
GRIS ORBEON 1.3.3.2-SNAPSHOT 7 / 17

Part C1 – Project Description

a) State of the art
Development in the field of high-strength steels is driven mainly by the automotive industry
with the aim to develop new affordable materials with excellent mechanical properties. That
leads to weight reduction of individual components and reduction of fuel consumption [1-4].
Another important criteria is the continuous improvement of passenger safety during a car
crash. These requirements can be met by using advanced third generation high strength steels
(AHSS). This generation builds on the development of first and second generation high
strength steels, which has been under way since the 60s of the last century and try to combine
the advantages of both. It is mostly medium manganese steel with a manganese content
between 3 – 12 wt.%, the carbon content of about 0.2 % and a small proportion of other
alloying elements such as Si and Al [1, 4]. The advantage of these steels is that they can use
a large number of strengthening mechanisms from solid solution strengthening to TRIP
(transformation induced plasticity) and TWIP (twinning induced plasticity) effect [2].
The resulting microstructure of medium manganese AHSS is based on an increasing amount
of hard phases and the fraction of retained austenite which is higher than typical for TRIP steels
[3]. There is a substitution of polygonal ferrite by acicular or bainitic ferrite, no carbide bainite
and martensite, together with the stabilized retained austenite [2]. In some cases, micro
alloying with V, Ti or Nb is used as a further strengthening mechanism [2].
Typical processing of these steels consists of hot rolling or cold rolling followed by intercritical
annealing (IA) also called austenite-reverted annealing process (ART) [1,5]. After hot rolling,
the structure is predominantly martensitic. There are large differences between hot rolled and
cold rolled microstructure (after annealing) in the morphology of the individual structural
components. Hot rolled steel followed by intercritical annealing exhibits a nano-laminate
microstructure consisting of two phases, where gamma reversion occurs without
recrystallization of the martensitic matrix during annealing [1,5]. During intercritial annealing of
the cold rolled steel, the active recrystallization of the martensitic matrix and the austenite
reversion simultaneously occur, resulting in nano-scale globular morphology of dual structure.
These differences in microstructure morphology in these two methods significantly affect
mechanical properties such as tensile strength, impact toughness, hydrogen embrittlement,
and fatigue resistance.
Warm-rolled steels achieved better mechanical properties after IA compared to the hot-rolled
and annealed steels. Warm forming provides a very fine grain structure with increased yield
strength and lower transition temperature [6].
The mechanical properties of the medium manganese steels were further improved by the
addition of aluminium, which allows the TRIP and TWIP effect to be joined during plastic
deformation [1, 7-10]. The addition of Al activates the TWIP mechanism by increasing the
stacking fault energy (SFE) in the retained/reversion austenite to the required values of about
20 – 40 mJ/m2 [7]. This makes it possible to activate the TWIP mechanism in the retained
austenite already at low deformation values, and the TRIP effect takes place at the
intersections of the twin-twin.
Aluminium is also added to increase A c1 and A c3 transformation temperatures. This makes it
possible to increase the temperature of intercritical annealing and shorten holding time at this
temperature. Due to the higher manganese content, the reversion austenite is transformed at
a lower temperature, and therefore intercritical annealing is required to be carried out at
temperatures of about 680 °C [11]. However, the structure cannot recrystallize and manganese
cannot be redistributed from ferrite to austenite at this temperature. If the annealing is carried
out at a sufficiently high temperature, a high amount of reversion austenite is formed. This
reversion austenite in not thermal stable and easy transforms into deformation-induced
martensite already at low deformation. In the case of Fe-0.12C-5Mn-0.5Si steel, when using
3 % Al alloying, the reversion austenite fraction is reduced to 20 – 30 % when using an
intercritical annealing temperature of 700 – 800 °C, which is already enough to start
recrystallization [11]. To avoid nozzle clogging during continuous casting it is good to have
aluminium content below 3% [12].
8 / 17 GRIS ORBEON 1.3.3.2-SNAPSHOT

Much of the work was devoted to the research of parameters of subsequent intercritical
annealing as well as to suitable parameters of hot or cold forming, in most cases sheet metal
forming [1-4, 6-10]. Another possibility for forming these materials is the warm incremental bar
forming by using helical rolling. The rolling stand available at the applicant’s workplace is made
up of a trio of milling rollers for efficient forming of solid material. These three rollers are offset
by 120° to each other (Figure 1). Each roller is equipped with a separate drive and the speed
of these rollers is synchronized.

Although medium manganese steels achieve excellent combinations of mechanical properties,
such as 1000 MPa at a ductility of 40 %, but relatively low yield strengths in the range of
400 – 500 MPa [13]. Warm forming (500 – 800 °C) could be the way how to improve this value
due to the formation of a very fine microstructure [6, 14,15]. The principle of the incremental
forming is inserting deformation in very small steps which allows bars to be reduced from 30
to 12 mm. Thanks to this principle it is possible to roll AHSS as well.
This would produce high-quality semi-finished products with a good combination of yield
strength, ultimate tensile strength and ductility, as well as a lower transition temperature
between the ductile and brittle fracture. The helical rolling mill HDQT-R 30-12 was used for the
described investigations (Figure 2).

Preliminary work
As part of the preliminary work at RTI, the heat and thermomechanical treatment were carried
out on the medium manganese steels with different Mn and Al ratio [16]. It was found out that
the multiphase structure could be obtained and that it is important to have a convenient Mn/Al
ratio to get good forging and casting conditions. Also, the incremental rolling was carried out
on the different types of steels to find the best combination of the rolling parameters [17].

b) Substance and current relevance of the project topic, the project goals, investigation
methods, strategy, methods, schedule and stages
The third generation of medium manganese steels using a variety of strengthening
mechanisms. It is possible to achieve ultimate tensile strength of more than 1300 MPa with
ductility higher than 30%. As a result, it can help to save material, which not only reduces the
weight but also the cost of final products. It is necessary to test its behaviour and perform
optimization of forming parameters and subsequent IA, to achieve required microstructures
and mechanical properties. In the proposed project, an extensive experimental program will
be conducted to understand the behaviour of these steels during incremental forming with
subsequent heat treatment, thus expanding the processing of these steels.

Objectives
The aim of the project is to describe the bahavior of the AHSS, in particular, medium
manganese steels, during helical rolling and subsequent intercritical annealing with an iteration
of the parameters to obtain satisfied properties of the final product. This process will bring
excellent mechanical properties as well as deformation behavior. The helical rolling process

Figure 1: Helical rolling scheme
with formed bar Figure 2: Helical rolling mill (HDQT – R 30-12) of Regional
technological Institute
GRIS ORBEON 1.3.3.2-SNAPSHOT 9 / 17

makes it possible to reduce the rod diameter from 30 to 12 mm in several forming steps, with
the deformation being introduced in small forming steps. The focus of the project is on creating
a basic understanding of the metal-physical processes influenced by the different
thermomechanical treatment. In addition, critical conditions for the TMT of high-strength steels
are to be identified. Within the framework of this research project, scientifically proven models
are to be developed which map the relationship and interactions between the material, the
microstructural influencing factors and the process control on the results of the
thermomechanical treatment with regard to mechanical properties.

The planned research project is divided into three sub-goals:
 Characterization of the metal-physical mechanisms with consideration of the
microstructural development of selected high-strength steels, with a manganese
content between 3 and 7 wt.% and an aluminium content between 2 and 3 %, during
different thermomechanical treatment (TMT before phase transformation in the stable
and metastable austenite region as well as during phase transformation).
 Determination of the effects of the thermomechanical process parameters on the
resulting mechanical properties.
 Development of phenomenological models to identify the TMT process windows for
defined mechanical properties.

Work programme incl. proposed research methods
The work programme is designed for a period of 3 years and consists of five parts. The main
point of the cooperation between RTI and IWP is to connect the field of materials science and
production science, which are essential for the success of the project. To achieve this goal,
experimental as well as simulative thermodynamic and thermomechanical investigations are
carried out. The statistical design and evaluation of experiments are integrated into each WP
in order to lower the effort involved and to evaluate the test results. This leads to a reduction
of the experimental scope, while at the same time gaining the same amount of knowledge.

WP 1. Material development
The design of chemical composition of experimental steels is based on the concept of medium
manganese high-strength steel, where the main focus is on achieving a high elongation of over
30 % with an ultimate tensile strength exceeding 1,300 MPa. A higher Mn content of 3 – 7 %
is chosen to obtain a higher proportion of reversion austenite during intercritical annealing. Mn
reduces the temperature of A 1 and expends the processing window. It is also used to stabilize
reversion austenite. Moreover, Mn increases hardenability and strongly reduces the critical
cooling rate in steels. Steels with higher Mn content exhibit deformation-induced martensite
transformation and also the deformation-induced twinning was found in steels with 6-12 % Mn.
The problem is, that the temperature of IA would be around 600 – 700 °C. On that temperature
the content of reversion austenite would be very high and without sufficient thermal stability.
To improve this situation aluminium is added. Aluminium increases the A 1 and A 3-temperature
and allows to increase the temperature of IA as well as reduce annealing time. From the
metallurgical point of view, the maximum content of aluminium should be around 3 %.

WP 1,1 Production of the experimental materials (RTI+IWP)
Within the preparation work, thermodynamic calculations and a study to analyze the effect of
alloying elements on the resulting yield strength as a function of the cooling rate, three alloys
(Table 1) were proposed on the base of the literature search and a thermodynamic calculation.
The produced castings are passed on to WP 1,2 for the production of bars.
Table 1: expected alloy composition in mass-%
Steel alloy C [%] Al max (%) Mn (%) Si (%) Nb (%) Mn/Al ratio
Alloy I 0.2 2 3 0.6 0.06 1.5
Alloy II 0.2 3 5 0.6 0.06 2.5
Alloy III 0.2 3 7 0.6 0.06 3.5
10 / 17 GRIS ORBEON 1.3.3.2-SNAPSHOT

WP 1,2 Forging of ingots into bars for incremental rolling stand HDQT-R-30-12
including their annealing (RTI)
The bars will be forged on a hydraulic press to a diameter of approx. 32 mm. After forging, the
bars will be annealed to relieve stress and obtain a suitable input structure for incremental
rolling. The annealing temperature will be chosen based on the chemical composition of the
individual experimental steels. The final machining decrease a diameter to 30 mm, which is
the input diameter of the rolling mill HDQT-R 30-12.

WP 2 Determination of the thermodynamically induced transformation kinetics
The research object of this WP is the material-scientific record, evaluation and interpretation
of the metal-physical effects under thermodynamic and thermomechanical treatment.

WP 2,1: Description of austenite transformation (IWP + RTI)
The WP evaluates and interprets austenitization during heating as a function of the heating
rate (continuous) and the holding time at a fixed temperature (isothermal). The heating
temperatures (approx. 800 to 1200 °C), the heating speeds (approx. 0.05 to 100 K/s) and the
holding times (approx. 10 to 600 s) are varied. First estimates of the austenite transformation
are made by thermodynamic calculations with JMatPro. These are compared with the
experimental results obtained in the dilatometer. The recorded dilatation curves (length
change-temperature curves) are analysed with regard to the transformation points (start and
end of austenite transformation) and used for the preparation of the time-temperature
austenitization (TTA) diagrams. These TTA diagrams are linked with the information and
results from WP 4. This makes it possible to show the influence of austenitization conditions
on the distribution of microstructural constituents and alloying elements (Al, Mn, etc.) and the
previous austenite grain sizes (WP 4,1). Furthermore, the mechanical properties (hardness)
(WP 4,2) are correlated with different austenitization conditions. Knowledge about the effects
of austenitization conditions on the microstructure is required for the design of the TMT
processes and is included in WP 2,2 and WP 2,3.

WP 2,2: Characterization of the transformation kinetics during cooling (IWP+ RTI)
The aim of this WP is to determine the temperature- and time-dependent phase
transformations after austenitization by generating isothermal and continuous time-
temperature transformation (CCT without deformation) diagrams. The planned dilatometric
investigations are based on the results from WP 2,1. In order to limit the investigation effort,
Origin is used to calculate the transformation behavior during cooling and to compare it with
the experimentally determined results. Various austenitization temperatures (between 800 and
1,200 °C) and duration (10 s to 600 s) are determined for the investigations. The cooling rates
(0.05 to 60 K/s) are varied to produce the continuous CCT diagrams. During the preparation
of the isothermal CCT diagrams, selected temperatures in the metastable austenite area are
quenched and kept isothermal. The metallography characterization (WP 4,1) and hardness
measurement (WP 4,2) are applied on the dilatation samples.

WP 2,3: Influence of forming on the transformation kinetics during cooling (IWP+ RTI)
The purpose of the WP is to determine the transformation and precipitation kinetics of the three
materials, which are influenced by the various thermomechanical parameters. The
investigations include forming before phase transformation in the stable and metastable
austenite region as well as during phase transformation. For the characterization, parameters
such as austenitization temperature, heating rate, duration, cooling rate and forming
temperatures for the corresponding treatment routes are determined on the basis of the results
from WP 2,1 and WP 2,2. In addition, the forming degrees and speeds are varied, taking into
account conventional forming parameters of massive forming.
The outputs from the deformation dilatometer would be temperature-length changes and flow
curves. The metallography observation (WP 4,1), as well as characterization of the mechanical
properties (WP 4,2), would be included in the evaluation. The results are incorporated in
GRIS ORBEON 1.3.3.2-SNAPSHOT 11 / 17

forming time-temperature transformation diagrams (CCT with deformation) to be prepared.
The results of WP 2 are used in WP 3 and WP 4.

WP 3 Description of material behavior and deformation capability during the TMT
process routes
The object of research is the technological analysis of the material behavior during the TMT
process routes and the comparison with the results under idealized test conditions (WP 2), e.g.
constant heating and cooling rates. The investigations are carried out using various
mechanical-technological test methods (see WP 3,1 to WP 3,2). Process parameters are the
hot flow behavior (WP 3,2) and the notched bar impact strength (WP 3,3). These are included
as indicators in WP 4.

WP 3,1 Determination of warm flow curves (IWP)
The task of the WP is to characterize the flow behavior of the test materials during hot sheet
metal forming in the uniaxial compressive stress state. In order to perform the temperature-
controlled compression tests in accordance with DIN 50106, the realistic test parameters such
as austenitizing temperature, time, test temperature and forming speed (up to 𝜑̇= 10 𝑠ିଵ )
must be determined based on the findings of WP 2. For the evaluation, hot flow curves
𝑘௙(𝜑,𝜑̇,𝑇) are recorded. The results serve to determine the limits of the flow behavior of the
investigated test materials.

WP 3,2 Transfer of the determined process window to the helical rolling process (RTI)
The output of the WP is the production of prototypes using the rolling process. Helical rolling
mill, HDQT – R 30-12 (see Figure 2) consists of three adjustable rolls. The forming is possible
between temperatures 700 – 1,250 °C. During the experiment the heating temperature, heating
rate, rollers speed, reduction and subsequent heat treatment will be tested. The cooling after
rolling could be done by water spray, water bath, slow cooling in the furnace or air cooling. The
next step will be IA with different heating temperature depending on the chemical composition
of the experimental steels to obtain desired multiphase structure and so to get the required
mechanical properties. The bar cross section can vary between 12 and 30 mm.
The process parameters derived from WP 4,2, 4,3 are used to configure the system. The aim
of the WP is to check the transferability of the experimentally determined parameters to the
real process. The mechanical properties of the samples produced are examined in WP 4.

WP 3,3 Construction and validation of the material model as well as process
simulation of rolling (IWP)
This WP uses existing simulation models and newly developed models for the fundamental
investigation of the topic. Simufact.Forming and/or Abaqus are used as simulation software. A
material model is created using the flow curves determined in WP 3,1. The helical rolling is
simulated with the three materials. The simulation results are compared with the samples
generated in WP 3,2. The material models are validated with the findings of WP 4.

WP 4 Determination and evaluation of material and component properties as
a function of the TMT
Within the framework of WP 4, the metal-physical effects of TMT and their influence on the
microstructure are recorded. For this purpose, the samples treated homogeneously in the
dilatometer in WP 2 and inhomogeneously in WP 2,3 are examined microstructurally (WP 4,1)
and with regard to their mechanical properties (WP 4,2).

WP 4,1: Characterization of the microstructure (IWP + RTI)
The specimens homogeneously treated by dilatometry over the entire specimen cross-section
(WP 2,1, WP 2,2 and WP 2,3) and the inhomogeneous specimens (from WP 3,2) with respect
to the degrees of deformation and temperatures introduced are examined microstructurally.
The task within WP 4,1 consists in the analysis and quantification of the microstructural
constituents (retained austenite), grain sizes and phase fractions depending on the respective
varied influencing variables:
12 / 17 GRIS ORBEON 1.3.3.2-SNAPSHOT

 WP 1,2: Analysis of the microstructural formation of the initial condition
 WP 2,1 (TTA experiments): Influence of heating (variation of heating rate and holding
time at different austenitization temperatures) on the formation of the microstructure
(carbide distribution, grain size)
 WP 2,2 (CCT without deformation experiments): Microstructure formation as a
function of cooling rate
 WP 2,3 (CCT with deformation experiments): Influence of Forming on Cooling Speed
and Recrystallization Behavior
 WP 3,1+3,2 Influence of varying degrees of deformation and temperatures
 WP 4,2: Formation of the microstructure for the representation of the influence on the
mechanical material properties
The characterization is carried out by an optical microscope. The composition of the
microstructure is determined with regard to the microstructural constituents (martensite, ferrite,
austenite, retained austenite) and the previous austenite grain sizes. Furthermore, electron
microscope examinations (SEM, TEM, EDXS) are carried out, which provide information about
the finest precipitates and the local chemical composition. The results provide information
about the interactions of the process parameters of the individual TMT process routes and
their effects on the microstructure of the material.

WP 4,2 Analysis of the resulting mechanical properties of materials and components
(IWP+RTI)
The aim of the WP is the determination and interpretation of the mechanical properties at
room temperature resulting from the thermomechanical treatment. The focus is on:
 WP 2,1; 2,2; 2,3 (TTA/CCT without and with deformation -diagrams): Influence of the
TMT routes on mechanical material properties resulting in results
 WP 3,1; 3,2: Influence of varying forming and temperature degrees on the samples
and bars
 WP 4,1: Relationship between microstructure and resulting mechanical properties as
a function of experimental parameters
The tests are carried out with the Vickers hardness measurement, tensile test in accordance
with ČSN EN ISO 6892-1, compression tests in accordance with DIN 50106. Since the degree
of deformation during helical rolling depending on the distance from the surface of the rod,
which results in affecting the structure and thus the mechanical properties, it is also necessary
to determine local mechanical properties. Local mechanical properties will be determined by
mini-tensile samples with active parts of approx. 2 x 1.2 x 5 mm and will be evaluated according
to ČSN EN ISO 6892-1. Particular attention will be paid to the surface layers and the center of
the bars. This will also describe the deformation penetration into the formed material at various
forming parameters and its influence on the structure development during subsequent heat
treatment. New testing machine suitable for examination of small samples will be used for
testing (device price quotations, see. attachment).

WP 4,3 Analysis of notched bar impact strength (RTI)
In addition to the hot flow curves, the notched bar impact strength according to ČSN EN ISO
148-1 is required as a function of the temperature for a comprehensive description of the
material behavior. The notched bar impact energy W [J] is thus determined for a specific
material at a specific temperature. The determination of the notched bar impact energy takes
place under consideration of the specified temperature regime of the TMT routes (WP 2) and
at various relevant forming temperatures. Special attention is paid to this:
 WP 3,2 Influence of the TMT routes on steel toughness

WP 5 Process design of different TMT process routes
In WP 4, the results from WP 2, WP 3 and WP 4 are combined in order to map the mechanical
properties during processing the high-strength steels as a function of the TMT. This makes it
possible to identify suitable process windows.

GRIS ORBEON 1.3.3.2-SNAPSHOT 13 / 17

AP 5,1 Development of models for the prediction of mechanical properties (IWP + RTI)
The task of the WP is to classify the influences of the various process parameters (e.g.
austenitizing time, temperature, forming temperature, etc.) with regard to their significance for
the processing and service properties. For this purpose, all relations from WP 1, WP 2 and WP
3 determined using the statistical experimental design are incorporated into phenomenological
models in order to determine correlations between the process parameters and the resulting
mechanical characteristic values (hardness, yield strength, tensile strength, ductility) of the
investigated materials. Not only the direct influences are considered, i.e. the interaction of the
parameters with each other, but also the interactions of higher order are investigated.
Analytical models of the mould are developed on the basis of the correlations and significances
as well as weighting factors worked out by the statistical experimental design and the analysis
of variance.
𝐹௄௘௡௡௪௘௥௧ =𝑓൫𝑇஺,𝑡஺,𝑇̇஺,𝑇ఝ,𝜑,𝜑,̇𝑣଼ ହ⁄൯ (1)
The investigation of three different steels with varying aluminium and manganese contents
makes it possible to additionally determine the influence of the aluminium and manganese
contents on the mechanical characteristic values. When formulating the models, the
development of the (macro-)hardness as a function of the TMT process parameters is initially
the focus. In addition, further properties relevant for use such as strength (equivalent yield
strength 𝑅௣଴,ଶ) are to be correlated with the relevant TMT process parameters.

WP 5,2 Multivariable Optimization (IWP + RTI)
The aim is to identify a process window based on the results of WP 4,1 by multivariable
optimization (e.g. using the Newton method) in order to enable the setting of application-
oriented processing and service properties. This is an inverse optimization of the form
𝐹௉௥௢௭௘௦௦=𝑓ିଵ൫𝐹௄௘௡௡௪௘௥௧ை௣௧൯ (2).
The quality of the process windows depends on the predictive accuracy of the model
relationships identified in WP 5,1 from (1). As a result, suitable TMT process routes are to be
selected with the described optimization procedure under the objective of certain processing
and service properties. The determined TMT process routes are validated in WP 3,2 Rolling
tests and in WP 3,3 Simulation of rolling. This makes it possible to evaluate the optimized
process windows.

Milestones:
MS1: Description of the dominant microstructure mechanisms under the thermomechanical
influence of the experimental alloys [End Q4 year 1].
MS2: Description of the deformation behavior under different thermomechanical process
conditions [End Q1 year 3].
MS3: Presentation of the phenomenological model for the identification of the TMT process
windows for defined mechanical properties [End of project duration]

The knowledge and models gained in the project are used to define suitable TMT process
windows and thus to apply TMT for high-strength steels for the first time. Thus, the application
spectrum of high strength steels can be extended and the great potential of these steels can
be exploited. The application of the TMT should make it possible to achieve high degrees of
deformation and to produce components with high degrees of deformation. In addition, the
TMT, as described in the state of the art and in the company's own preliminary work, will
achieve improved mechanical properties.

e) description and justification of the necessity and contribution of cooperation with
the foreign proposer
The project will investigate in detail the behavior of medium manganese steels during
incremental forming and will look for the best combination of parameters to obtain the desired
final structure. RTI has extensive experience in thermal and thermomechanical processing of
high strength steels, while IWP, in turn, has high know-how in the field of hot forming including
14 / 17 GRIS ORBEON 1.3.3.2-SNAPSHOT

FEM simulations. Combining this knowledge will create the necessary environment for
achieving the project objectives.

Table 2: Timetable

f) existing and planned cooperation between the proposer and the foreign proposer
and foreign scientific institutions
In the areas of materials science and processing, cooperation of more than 45 years has
existed between UWB Pilsen and TU Chemnitz. Dr. Hana Jirková herself has personally
cooperated with the University in Chemnitz since 2002. RTI and IWP worked together on the
project partly funded by the Objective 3 programme of the European Regional Development
Fund for the last three years. Within the proposed project, very close cooperation is planned
throughout the project. The RTI has competences in the field of high strength steels and their
heat and thermomechanical treatment and the IWP's competences in the design of thermo-
mechanical treatments and FEM simulations.
The project proposer, RTI, conducts various research and development projects with a number
of foreign research institutions. Long-time cooperation has been maintained with the Slovak
University of Technology in Bratislava, Materials Research of the Slovak Academy of Sciences
(Košice, Slovakia) and the Faculty of Materials Science and Technology in Trnava, Slovakia.
An international project was carried out jointly with Fundació CTM Centre Tecnològic
(Barcelona, Spain), Fraunhofer Institute for Machine Tools and Forming Technology
(Chemnitz, Germany).

GRIS ORBEON 1.3.3.2-SNAPSHOT 15 / 17

g) Data on project proposer’s and foreign proposers’ preparedness
Equipment of the project proposer, University of West Bohemia
 HDQT R 30-12 device is constructed for diameter reduction of round bars with the use of
helical rolling. Maximal reduction of a diameter which can be proceed is from 30 mm to 12
mm. This device provides many modules for heat treatment after rolling including
quenching bath, cooling sprays and two furnaces
 Fast thermo-mechanical simulator with high-frequency resistance heating up to 1400°C.
Max. forming force 20 kN, max. velocity of the actuator 3 m/s
 Model of Hydraulic forging press CKW 600/ 1:10, 100 tons,300 mm stroke, forming speed
from 10 mm.s-1 to 120 mm.s-1
 Furnace LAC with possibility of Ar atmosphere and heating up to 1100 °
 Furnace for heat treatment BVD with heating up to 1300 °C
 Furnace LAC for heat treatment with heating up to 1280 °C
 A NanoTest Vantage nanoindenter with the loading range of 10 µN – 2 N
 Optical microscope Olympus
 Scanning electron microscope Zeiss Crossbeam 340-47-44
 Scanning electron microscope Zeiss EVO MA 25
 TESCAN VEGA SB Easy probe scanning electron microscope
 Equipment for wet blasting with abrasive
 JMatPro – analytical software for calculating materials properties
 ZWICK electromechanical test machine 250 kN
 ZWICK/ROELL HFP50 vibrophore for fatigue testing
 Charpy instrumented pendulum 150/300/450 J

Equipment and facilities of the foreign proposer, Chemnitz University of Technology;
 Universal testing machine INSPEKT® 150 kN with an integrated tribometer (Hegewald &
Peschke)
 Keyence® VHX-600 Digital microscope – 3D topography
 Inverted metallographic microscope Axio® Vert.A1 MAT (Carl Zeiss Microscopy GmbH)
 Surface roughness tester T1000 (HOMMEL-ETAMIC GmbH)
 Universal Hardness testing machine M1C 010 (EMCO-TEST)
 Laboratory furnace type LM 512 (Linn High Therm)
 Strip drawing tribological testing machine
 Equipment for metallographic preparation (cutting, mounting, grinding and polishing)
 Dual column eccentric press PED 100.3-S4
 Servo-electrical press (Dunkes)
 Simulation software: Simufact, Abaqus, JMatPro, Origin

g) Description of the project team
The team will be led by Dr.-Ing. Hana Jirková, Ph.D. She has got long-standing experience in
the field of design and material properties of steels, heat and thermomechanical treatment of
materials and she holds several renowned awards (participation 0.25). She will be responsible
for the design of chemical composition of experimental steels, microstructural analysis and
thermomechanical treatment and forming. She will prepare publications and reports.
Ing. Štěpán Jeníček – mechanical testing (sample preparation, evaluation of results after
tensile testing and notch impact testing), preparation of documents for the tender for the new
tensing machine (participation 0.13). Bc. Tomáš Janda (student) – thermomechanical
processing on the rolling stand, mechanical testing, JMatPro and Thermocalc calculations
(participation 0.25). M.Sc. Omid Khalaj, Ph.D. (postdok) – heat and thermomechanical
treatment, collaboration on the design of parameters for incremental rolling (participation 0.25).
All scientific members will be involved in the publication and report writing. There will be also
2 technicians (participation 0.75) – preparation of samples with water jet, machining and
electrical discharge machining for the forming, heat treatment and mechanical testing, forging
16 / 17 GRIS ORBEON 1.3.3.2-SNAPSHOT

of the ingots, preparation of the metallographic samples and documentation of the structures
with the optical microscope and basic scanning electron microscopy. A student with a closed
DPP contract will work about 200 hours/year and will assist with the evaluation of
metallographic analyses.

h) Literature sources
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properties of intercritically annealed medium-Mn steels. Materials Science and
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[2] Grajcar, A.; Kuziak, R.; Zalecki W.: Third generation of AHSS with increased fraction of
retained austenite for the automotive industry. Archives of Civil and Mechanical
Engineering. 2012, 12(3), 334–341.
[3] Aydin, H. et al.: Development of 3rd generation AHSS with medium Mn content alloying
compositions. Materials Science and Engineering A. 2013, 564, 501–508.
[4] Hu, B.; Luo, H.; Yang, F.; Dong, H.: Recent progress in medium-Mn steels made with new
designing strategies, a review. Journal of Materials Science and Technology. 2017,
33(12), 1457–1464.
[5] Ma, Yan. Medium-manganese steels processed by austenite-reverted-transformation
annealing for automotive applications. Materials Science and Technology (United
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[6] Zhang, R. et al.: Intercritical rolling induced ultrafine microstructure and excellent
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[7] Dumay, A. et al.: Influence of addition elements on the stacking-fault energy and
mechanical properties of an austenitic Fe–Mn–C steel. Materials Science and
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[8] Lee, S.; Lee, K.; De Cooman, B.C.: Observation of the TWIP+TRIP Plasticity-
Enhancement Mechanism in Al-Added 6 Wt Pct Medium Mn Steel.Metallurgical and
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[9] Lee, Ch. et al.: Coupled strengthening in a medium manganese lightweight steel with an
inhomogeneously grained structure of austenite. Acta Materialia. 2015, 84, 1–8.
[10] Lee, S.; De Cooman, B.C.: Effect of the intercritical annealing temperature on the
mechanical properties of 10 Pct Mn multi-phase steel. Metallurgical and Materials
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[11] Suh, D. W., et al.: Influence of Al on the microstructural evolution and mechanical behavior
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[12] Suh, D. W. et al.: Medium-alloy manganese-rich transformation-induced plasticity steels.
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[13] LEE, Y.-K.; HAN, J.: Current opinion in medium manganese steel. Materials Science and
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[14] Cao, W.Q. et al.: Microstructure and mechanical properties of Fe-0.2C-5Mn steel
processed by ART-annealing. Materials Science and Engineering A. 2011, 528(22–23),
6661–6666.
[15] Santos, D.B.; Bruzsek, R.K.; Rodrigues, P.C.M.; Pereloma, E.V.: Formation of ultra-fine
ferrite microstructure in warm rolled and annealed C-Mn steel. Materials Science and
Engineering A. 2003, 346(1–2), 189–195.
[16] Kučerová, L.; Jirková, H.; Volkmannová, J.; Vrtáček, J.: Effect of Aluminium and
Manganese contents on the microstructure development of forged and annealed TRIP
steel. Manufacturing Technology. 2018, 18(4), 605–610.
[17] Peković, M. et. al.: Termomechanické zpracování ocelí s použitím zařízení pro
inkrementální tváření tyčí HDQT-R 30-12 (Thermomechanical treatment of steels with
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