New Methods in Steel Design

Transcription

1 New Methods in Steel Design Collaborative Research Center SFB 761 Steel ab initio; quantum mechanics guided design of new Fe based materials

2 Outline Introduction New modeling tools New characterization tools New processes Conclusions 2

3 Decisions and Methods in Material Development high Stage of development Ris low Material; ime HSLA AHSS HMnS Industrial application Modeling HSLA: High Strength Low Alloy AHSS: Advanced High Strength Steels HMnS: High Manganese Steels 3

4 Formability Comparison Strength Formability of different steel concepts AHSS = Advanced High-Strength Steels Medium-Mn-Stähle (austenitic multiphase steels) High-Mn-Steels (austenitic steels) ferritic steels ferritic multiphase steels Strength 4

5 Deformation Mechanisms in High Manganese Steels g Dislocation generation and reactions ransformation during deformation winning during deformation Dislocation channels by intermetallics SLIP RIP WIP MBIP SLIP: Dislocation slip RIP: transfomation induced plasticity WIP: twinning induced plasticity MBIP: Microband induced plasticity 5

6 Outline Introduction New modeling tools New characterization tools New processes Conclusions 6

7 Manganese content Manganese content Deformation mechanisms I Method development SFE-Concept D-Mechanism map wt.-% Aluminum Carbon content Carbon content RIP: transfomation induced plasticity WIP: twinning induced plasticity a Martensite e Martensite SFE: Stacingfaultenergy A. Saeed-Abari, L. Mosecer, A. Schwedt, W. Blec: Metall. Mater. rans. A, 43A (2012)

8 Manganese content Deformation mechanisms II Method development SFE-Concept D-Mechanism map D-Mechanism map wt.-% Aluminum Carbon content RIP: transfomation induced plasticity WIP: twinning induced plasticity A. Saeed-Abari, L. Mosecer, A. Schwedt, W. Blec: Metall. Mater. rans. A, 43A (2012) MBIP: MicroBand Induced Plasticity W. Song,. Ingendahl, W. Blec: Acta Metall. Sin. (Engl. Lett.), 27 (2014)

9 ransfer project stainless WIP steels I Materials and process design for stainless WIP steel Method Development Materials Application Materials Processing Adoption of the SFB method to: different alloy system industrial process Fe-Cr-Mn-N Steel and process development in only 3 years. New material and process meet benchmar properties. Patent: EP Austenitic stainless steels Europäische Patentanmeldung Publication: L. Mosecer and A. Saeed-Abari, Sci. echnol. Adv. Mater. 14 (2013)

10 ransfer project stainless WIP steels II Method Development Materials Application Materials Processing Fe-Cr-Mn-N Request: YS > 500 MPa, A > 40% Patent: EP Austenitic stainless steels Europäische Patentanmeldung Publication: L. Mosecer and A. Saeed-Abari, Sci. echnol. Adv. Mater. 14 (2013)

11 rue stress / MPa Properties I Experiment Flow curves ab initio simulation Enthalpy of solutions of C in Fe-Mn-Octahedron X60Mn18 WIP WIP X60MnAl17-1 stainless X5CrNi18-10 steel Fe Mn rue plastic strain / - Steel denomination DIN EN and -2: WIP: X60Mn18 WIP Al: X60MnAl17-1 stainless steel: X5CrNi

12 rue stress / MPa Properties II new interpretation of results Experiment Flow curves Constitutive model Modelling approach yield strength: rue plastic strain / - X60Mn18 WIP WIP X60MnAl17-1 stainless X5CrNi18-10 steel Solid solution hardening s y (MPa) = (wt%C) - 2(wt%Mn) O. Bouaziz, H. Zurob, B. Chehab, J. D. Embury, S. Allain, M. Huang: Materials Science and echnology 27 (2011) Short range order + microstructure s SRO =M t SRO = M (E random E SRO ) / b 3 s y (MPa) = 90 + s SRO + 11,3 d -1/2 J.-H. Kang:. Ingendahl, J. von Appen, R. Dronsowsi, W. Blec: Materials Science and Engineering A (2014) Steel denomination DIN EN and -2: WIP: X60Mn18 WIP Al: X60MnAl17-1 stainless steel: X5CrNi

13 Outline Introduction New modeling tools New characterization tools New processes Conclusions 13

14 Characterisation quantitative analysis on nm-scale FIB arget preparation SEM / EM AP Grain boundaries Orientation 3D-Element distribution FIB: Focussed Ion Beam SEM: Scanning ransmission Electron Microscope AP: Atom Probe omography Herbig et al: Physical Review Letters 112 (12)

15 Microstructure local equilibrium K-Phase no K-Phase Fe-30Mn-8Al-1.2C wt. 15

16 nm - Precipitates of -Phase (001) κ AP Atom Probe omography DESY Synchrotron Diffraction 16

17 Outline Introduction New modeling tools New characterization tools New processes Conclusions 17

18 Material Design Process chain for the production of Fe-Mn-Al-C Fe-Mn-Al-C-Crashboxen with different heat treatment SFE: Stacingfaultenergy 18

19 Materials and Process Design I Substitution of recrystallization annealing by recovery annealing before cold rolling after cold rolling after recovery annealing Deformation wins O. Bouaziz, C.P. Scott, G. Petitgand: Scripta Mater., 60 (2009) H.. Wang, N.R. ao, K. Lu: Acta Mater., 60 (2012) C. Haase et al.: Met. Mater. rans. A, 44 (2013) Wolfgang Mechanismenorientiertes Blec Werstoff- und Prozessdesign Christian Haase

20 Materials and Process Design II RX 1 µm 1 µm 50 % C/30 min 40 % C/1 h win boundaries are heat resistant C. Haase et al.: Acta Mater., 80 (2014)

21 echnische technical Spannung stress (MPa) (MPa) Yield strength 0.2% (MPa) Materials and Process Design III technical echnische strain Dehnung (%) (%) fracture strain (%) Variation of rolling degree and annealing parameters allows the adjustment of final mechanical properties CR: cold rolled RC: recovered RX: recrystallized C. Haase et al.: Acta Mater., 80 (2014) C. Haase et al.: Adv. Mater. Res., 922 (2014)

22 Outline Introduction New modeling tools New characterization tools New processes Conclusions 22

23 Nano-Engineered Steels g ransformation + precipitation ransformation during deformation winning during deformation Dislocation channels by intermetallics Bainite RIP WIP MBIP 23

24 Microstructure length scales of different steels Nanostructured steels Ultra Fine Grain UFG hermo Mechanically Processed MP conventional steel NS 1 m 10-3 m 10-6 m 10-9 nm Quelle: Müller Weingarten AG 24

25 Vision I: Quantitative Understanding of Parameters bcc fcc hcp FM PM Crystall structure Magnetism SLIP RIP WIP MBIP a g retained γ α Multiphases Deformation mechanisms 25

26 stress s [MPa] Vision II: Individual adjustment of mechanical properties for stress exposed optimized components RIP Steel WIP Steel source: Future Steel Vehicle, World Auto Steel Report strain e [%] New quality level in material development 26

27 New Methods in Steel Design Collaborative Research Center SFB 761 Steel ab initio; quantum mechanics guided design of new Fe based materials