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C4 - Microstructural Analysis - FEA (funding period 2)

Analysis of load history dependent evolution of damage and microstructure for the numerical design of sheet - bulk metal forming processes

Project Status: finished

Last Update: 23.01.2017


The aim of this project is the numerical failure prediction in sheet-bulk forming processes on the basis of coupled damage models, which are motivated and validated by microstructural analysis. This serves the purpose to predict the remaining formability and a safe process window for complex multi-step sheet-bulk forming processes.

Materials with ductile damage and failure behavior exhibit damage mechanisms governed by the three stages nucleation, growth and coalescence of nano- as well as micro-voids. From the onset of deformation until failure, the cohesion of the material is influenced, which corresponds macroscopically to a reduction of strength. An extended Lemaitre damage model and an extended Gurson model for porous plasticity are applied to model such behavior. The link between microstructural analysis and the forming simulation arises in the context of the Gurson model by the evaluation of the nucleation of new voids for the determination of material parameters. The research focus lies on the analysis of advanced multi-phase materials and the investigation of the influence of anisotropic damage as well as loading path changes on sheet-bulk forming.

Distinct differences in the mechanisms of void nucleation were determined by a specially suited ion polishing method and corresponding preparation technique for scanning-electron-microscopy (SEM) samples for the single phase ferritic steel DC04 compared to ferritic-martensitic dual phase steel DP600 (see Figure 1). Voids nucleate with progressing deformation at precipitates (mostly manganese sulfide). The nucleation occurs usually close to grain boundaries. The voids nucleate predominantly in the martensite phase and in the vicinity of phase boundaries in the dual phase steel due to the more complex microstructure.

Figure 1. Different mechanisms of void nucleation in single phase ferritic steel DC04 (nucleation at manganese sulfide) and ferritic-martensitic dual phase steel DP600 (nucleation at phase boundaries)after 15 % strain in uniaxial tension (Gerstein et al., 2015)

Moreover, deformed specimens are analyzed by EBSD (electron-backscatter diffraction) to determine correlations between crystallographic orientation and void evolution. The weakening of the material is taken into account by the void volume fraction in the Gurson model. Therefore a three-dimensional quantification and visualization of the void topography renders important data for modelling. The right image shows an assembly of different SEM images.



Figure 2. EBSD image of the damaged region in steel DP600 and 3D-visualization of void coalescence (uniaxial tension, 10 % tensile strain) 


Damage models, which consider ideal spherical voids in case of the Gurson model, were applied in the first period of funding. However, SEM investigations of dual phase steel DP600 indicate that voids exhibit an ellipsoidal topology with progressing deformation. Besides supporting the development of material models in this project, the microstructural analysis renders valuable information for the subproject C2.


Figure 3. Almost spherical micro void in as received material and ellipsoidal void geometry after uniaxial tension (15 % strain) in DP600. 


Finite element simulations of a indentation process into a thick sheet (subproject A4) with an extended Lemaitre model for anisotropic damage show better results than a model with isotropic damage. A second-order tensor considers efficiently the effect of anisotropic microstructural processes such as void growth instead of the scalar damage variable in the isotropic case. The penetration depth is 10 % larger for the anisotropic model and shows a better agreement with the experiment. This continuum mechanical approach enables the design of suitable process strategies for sheet-bulk forming.


Figure 4. More realistic prediction of failure with anisotropic Lemaitre damage model for penetration depth h




Working Groups



    • Gerstein, G.; Bruchanov, A. A.; Dyachok, D. V.; Nürnberger, F.: The effect of texture in modeling deformation processes of bcc steel sheets. In: Materials Letters, 164(2016), pp. 356-359
    • Besserer, H.; Hildenbrand, P.; Gerstein, G.; Nürnberger, F.; Merklein, M.; Maier, H.: Ductile Damage and Fatigue Behavior of Semi-Finished Tailored Blanks for Sheet-Bulk Metal Forming Processes. In: Journal of Materials Engineering and Performance, 25(2016)3, pp. 1136-1142
    • Besserer, H.; Gerstein, G.; Maier, H.; Nürnberger, F.: Specimen Preparation by Ion Beam Slope Cutting for Characterization of Ductile Damage by Scanning Electron Microscopy. In: Microscopy Research and Technique, 79(2016)4, pp. 321-327
    • Isik, K.; Gerstein, G.; Schneider, T.; Schulte, R.; Clausmeyer, T.; Nürnberger, F.; Vucetic, M.; Koch, S.; Hübner, S.; Behrens, B.; Tekkaya, A.; Merklein, M.: Investigations of ductile damage during the process chains of toothed functional components manufactured by sheet-bulk metal forming. In: Production Engineering, 10(2016)1, pp. 5-15
    • Besserer, H.; Gerstein, G.; Dalinger, A.; Jablonik, L.; Rodman, D.; Nürnberger, F.: Ion Beam Processing in the Sample Preparation for the Analysis of Ductile Damage in Deep Drawing Steels. In: Praktische Metallographie, 53(2016)4, pp. 221-236
    • Beese, S.; Beyer, F.; Blum, H.; Isik, K.; Kumor, D.; Rademacher, A.; Tekkaya, A.; Willner, K.; Wriggers, P.; Zeller, S.; Löhnert, S.: Simulation of Sheet-Bulk Metal Forming Processes with Simufact.forming using User-Subroutines. In: ESAFORM (Edt.): Proceedings of the 19th International ESAFORM Conference on Material Forming, DOI: 10.1063/1.4963457, (2016), Nantes, Frankreich, published
    • Gerstein, G.; Nürnberger, F.; Maier, H.: Evolution of void shape anisotropy in deformed bcc steels. In: TMS (Edt.): TMS 145. Annual Meeting, Proceedings of the EPD Congress, (2016), Hoboken, New Jersey: John Wiley & Sons, Inc., pp. 173-179
    • Isik, K.; Wernicke, S.; Silva, M.B.; Martins, P.A.F.; Tekkaya, A.: Failure by fracture in sheet–bulk metal forming. In: Journal of Strain Analysis; DOI: 10.1177/0309324716639773, 51(2016)5, pp. 387-394
    • Isik, K.; Gerstein, G.; Clausmeyer, T.; Nürnberger, F.; Tekkaya, A.; Maier, H.: Evaluation of Void Nucleation and Development during Plastic Deformation of Dual-Phase Steel DP600. In: Steel Research Int., DOI: 10.1002/srin.201500483, (2016), published
    • M.B. Silva; Isik, K.; Tekkaya, A.; A.G. Atkins; P.A.F. Martins: Fracture toughness and failure limits in sheet metal forming. In: Journal of Materials Processing Technology, 234(2016), pp. 249-258
    • Isik, K.; Gerstein, G.; , .; Clausmeyer, T.; Nürnberger, F.; Maier, H.; Tekkaya, A.: Investigations of ductile damage in DP600 and DC04 deep drawing steel sheets during punching. In: Procedia Structural Integrity, 2(2016), pp. 673-680
    • Bryukhanov, A. A.; Gerstein, G.; Dyachok, D. A.; Nürnberger, F.: Effect of deformation texture on the anisotropy of elasticity and damage of two-phase steel sheets. In: The Physics of Metals and Metallography, 117(2016)7, pp. 719-724


    • Gerstein, G.; Besserer, H.; Nürnberger, F.; Maier, H.: Comparison of the Mechanisms of Void Formation by Plastic Deformation in Single- and Dual-Phase BCC- Steels. In: 2015 TMS Annual Meeting & Exhibition, Proceedings Characterization of Minerals, Metals and Materials, (2015), Hoboken, New Jersey: Wiley, pp. 75-81
    • Zeller, S.; Beese, S.; Gerstein, G.; Isik, K.; Löhnert, S.; Nürnberger, F.; Wriggers, P.; Maier, H.; Tekkaya, A.: Möglichkeiten der simulativen Vorhersage von Temperaturentwicklung und Bauteilversagen infolge plastischer Deformation bei DP600 Bauteilen. In: Tekkaya, A. E.; Liewald, M.; Merklein, M.; Behrens, B.-A. (Edt.): Tagungsband zum 18. Workshop Simulation in der Umformtechnik & 3. Industriekolloquium Blechmassivumformung 2015 - DFG Transregio 73, (2015), Aachen: Shaker Verlag, pp. 113-128
    • Gerstein, G.; Besserer, H.; Jablonik, L.; Dalinger, A.; Nürnberger, F.; Höpner, A.: Präparation plastisch umgeformter Stahlproben durch Ionenstrahlbearbeitung für die Untersuchung von duktiler Schädigung. In: Schneider, G.; Zschech, E.; Petzow, G. (Edt.): Fortschritte in der Metallographie. Berichte der 49. Metallographie-Tagung Dresden, 16. bis 18. September 2015, 47(2015), Sankt Augustin: DGM Inventum, pp. 153-158
    • Q. Yin; Soyarslan, C.; Isik, K.; Tekkaya, A.: A grooved in-plane torsion test for the investigation of shear fracture in sheet materials. In: International Journal of Solids and Structures, 66(2015), pp. 121-132
    • Isik, K.; Silva, M.B.; Atkins, A.G.; Tekkaya, A.; Martins. P.A.F.: A New test for determining fracture thoughness in plane stress in mode II . In: Journal of Strain Analysis for Engineering Design, 50(2015)4, pp. 221-231
    • Silva, M.B.; Isik, K.; Tekkaya, A.; Martins, P.A.F.: Fracture loci in sheet metal forming: A Review. In: Acta Metallurgica Sinica (English Letters), 28(2015)12, pp. 1415-1425


    • Sieczkarek, P.; Isik, K.; Martins, P. A. F.; Tekkaya, A.: Mechanics of Sheet-Bulk Indentation. In: Journal of Materials Processing Technology (JMPT), 214(2014), Elsevier, pp. 2387-2394
    • Isik, K.; Silva, M.B.; Tekkaya, A.; Martins P.A.F.: Formability limits by fracture in sheet metal forming. In: Journal of Materials Processing Technology, 214(2014), pp. 1557-1565
    • Faßmann, D.: Beitrag zur wechselseitigen Beeinflussung von Mikrostruktur und Blechmassivumformprozess. Dissertation, Berichte aus dem IW, 1(2014), Hannover: PZH-Verlag, published


    • Lehmann, E.; Faßmann, D.; Löhnert, S.; Schaper, M.; Wriggers, P.: Texture development and formability prediction for pre-textured cold rolled body-centred cubic steel. In: International Journal of Engineering Science, 68(2013), pp. 24-37
    • Isik, K.; Soyarslan, C.; Tekkaya, A.: Continuum Damage Mechanics (CDM) Based Local Approach to the Sheet-Bulk Metal Formability Prediction. In: Advanced Materials Research, 769(2013), pp. 205-212
    • Hokhman, O. R.; Volchok, N. A.; Faßmann, D.: Distribution of Microdefects in Sheets of St1.03-12 Low-Carbon Steel in Tension at Different Rates. In: Materials Science , 49(2013)2, pp. 199-205
    • Faßmann, D.; Isik, K.; Zeller, S.; Beese, S.; Nürnberger, F.; Schaper, M.; Tekkaya, A.; Löhnert, S.; Wriggers, P.: Abbildung des Werkstoffverhaltens von ferritischem Stahl in numerischen Modellen zur Darstellung von Blechmassivumformprozessen bei zyklischen Belastungspfaden. In: M. Merklein, B.-A. Behrens, A.E. Tekkaya (Edt.): Tagungsband zum 2. Erlanger Workshop Blechmassivumformung 2013, (2013), pp. 69-84



      • 18.02.2016: Gerstein, G.: Evolution of void shape anisotropy in deformed bcc steels, TMS 2016, Nashville, Tennessee
      • 27.04.2016: Kumor, D.: Simulation of Sheet-Bulk Metal Forming Processes with Simufact.forming using User-Subroutines, 19th ESAFORM Conference, Nantes, Frankreich
      • 18.05.2016: Isik, K.: Modelling shearing cutting process of high carbon steel using Lemaitre damage model , ICOMP2016, Liège, Belgien
      • 02.06.2016: Isik, K.: Investigations of ductile damage during the process chains of toothed functional components manufactured by sheet-bulk metal forming , 17. Simufact Roundtable, Marburg


      • 17.03.2015: Nürnberger, F.: Comparsion of the mechanisms of void formation by plastic deformation in single- and dual-phase bcc-steels, TMS 2015, Orlando, Florida
      • 27.05.2015: Gerstein, G.: The effect of texture in modeling deformation processes of body-centered-cubic steel sheets , 4th International Conference on Material Modeling, Berkeley, California, USA
      • 17.09.2015: Gerstein, G.: Präparation plastisch umgeformter Stahlproben durch Ionenstrahlbearbeitung für die Untersuchung von duktiler Schädigung, 49. Metallographie-Tagung, Dresden


      • 07.11.2014: Isik, K.: Generalized forming limit curves with integrated fracture limits, FLC 2014 Workshop, Zürich, Schweiz


      • 09.04.2013: Faßmann, D.: Duktile Schädigung in der Blechmassivumformung Festigkeitseinschränkende Poren- und Rissbildung im Fertigungsprozess, 13. Werkstoffforum. Hannover Messe 2013, Hannover
      • 06.06.2013: Isik, K.: Modeling anisotropic ductile damage in sheet metal forming, The Third International Conference on Computational Modeling of Fracture and Failure of Materials and Structure, Prague, Czech Republic
      • 13.11.2013: Faßmann, D.: Abbildung des Werkstoffverhaltens von ferritischem Stahl in numerischen Modellen zur Darstellung von Blechmassivumformprozessen bei zyklischen Belastungspfaden, Erlangen