Springback-free mechanism in hot stamping of ultra-high-strength steel parts and deformation behaviour and quenchability for thin sheet

ORIGINAL ARTICLE
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Abstract

The springback-free mechanism in hot stamping of ultra-high-strength steel parts was clarified by the mechanical, thermal and transformation viewpoints. In hot stamping, the effects of elastic recovery during unloading and thermal shrinkage on the springback are comparatively small, but the effect of the phase transformation is critical. Volume expansion occurs primarily upon the start of the martensitic transformation, and plastic deformation is induced by the volume expansion during holding at the bottom dead centre, causing the springback including the post-stamping deformation to disappear. It was observed from well-organised experiments that holding at the bottom dead centre until the martensite finish temperature prevents the springback, and the springback-free mechanism in hot stamping of ultra-high-strength steel parts was clarified from the observation. The springback behaviour in hot stamping of a thin steel sheet with 0.6 mm thickness was explained from the above mechanism, and the deformation behaviour and quenchability for the thin sheet were examined. A sufficient holding time at the bottom dead centre was more closely associated with the prevention of springback rather than sufficient hardening. Additionally, local thinning around the bottom corner of a bent thin sheet was prevented by optimising the transfer time from the furnace.

Keywords

Hot stamping Springback-free Thin sheet Local thinning 

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References

  1. 1.
    Åkerström P, Oldenburg M (2006) Austenite decomposition during press hardening of a boron steel—computer simulation and test. J Mater Process Technol 174(1–3):399–406CrossRefGoogle Scholar
  2. 2.
    Mori K, Bariani PF, Behrens BA, Brosius A, Bruschi S, Maeno T, Merklein M, Yanagimoto J (2017) Hot stamping of ultra-high strength steel parts. CIRP Ann Manuf Technol 66(2):755–777CrossRefGoogle Scholar
  3. 3.
    Mori K, Maki S, Tanaka Y (2005) Warm and hot stamping of ultra high tensile strength steel sheets using resistance heating. CIRP Ann Manuf Technol 54(1):209–212CrossRefGoogle Scholar
  4. 4.
    Yanagimoto J, Oyamada K (2005) Springback of high-strength steel after hot and warm sheet formings. CIRP Ann Manuf Technol 54(1):213–216CrossRefGoogle Scholar
  5. 5.
    Yanagimoto J, Oyamada K (2007) Mechanism of springback-free bending of high-strength steel sheets under warm forming conditions. CIRP Ann Manuf Technol 56(1):265–268CrossRefGoogle Scholar
  6. 6.
    Kusumi K, Yamamoto S, Takeshita T, Abe M (2008) The effect of martensite transformation on shape fixability in the hot stamping process. Steel Res Int 79:71–76Google Scholar
  7. 7.
    Senuma T, Magome H, Tanabe A, Takemoto Y (2009) New hot stamping technology characterized by its high productivity. Proc of 2nd Int Conf on Hot Sheet Metal Forming of High-Performance Steel, Lulea, pp. 221–228Google Scholar
  8. 8.
    Xing ZW, Bao J, Yang YY (2009) Numerical simulation of hot stamping of quenchable boron steel. Mater Sci Eng A 499(1–2):28–31CrossRefGoogle Scholar
  9. 9.
    Lee MG, Kim SJ, Han HN (2009) Finite element investigations for the role of transformation plasticity on springback in hot press forming process. Comput Mater Sci 47(2):556–567CrossRefGoogle Scholar
  10. 10.
    Bao J, Liu H, Xing Z, Song B, Yang Y (2013) Springback of hot stamping and die quenching with ultra-high-strength boron steel. Eng Rev 33(3):151–156Google Scholar
  11. 11.
    Bok HH, Choi JW, Suh DW, Lee MG, Barlat F (2015) Stress development and shape change during press-hardening process using phase-transformation-based finite element analysis. Int J Plast 73:142–170CrossRefGoogle Scholar
  12. 12.
    Lee M, Baeck S, Kang CG (2012) Investigation of thin boron steel sheet formability in hot deep-drawing processes according to process parameters. Proc Inst Mech Eng B J Eng Manuf 226(5):898–908CrossRefGoogle Scholar
  13. 13.
    Georgiadis G, Tekkaya AE, Weigert P, Weiher J, Kurz H (2014) Investigations on the manufacturability of thin press hardened steel components. Procedia CIRP 18:74–79CrossRefGoogle Scholar
  14. 14.
    Nakagawa Y, Maeno T, Mori K (2015) Forming and quenching behaviours in hot stamping of thin quenchable sheets. MATEC Web Conf 21(05002):1–7Google Scholar
  15. 15.
    Georgiadis G, Tekkaya A E, Weigert P, Horneber S, Kuhnle P A (2017) Formability analysis of thin press hardening steel sheets under isothermal and non-isothermal conditions. Int J Mater Form In pressGoogle Scholar
  16. 16.
    Merklein M, Lechler J, Geiger M (2006) Characterisation of the flow properties of the quenchenable ultra high strength steel 22MnB5. CIRP Ann Manuf Technol 55(1):229–232CrossRefGoogle Scholar
  17. 17.
    Bok HH, Kim SN, Suh DW, Barlat F, Lee MG (2015) Non-isothermal kinetics model to predict accurate phase transformation and hardness of 22MnB5 boron steel. Mater Sci Eng A 626(25):67–73CrossRefGoogle Scholar
  18. 18.
    Billur E, Porzner H, Lorenz D, Holecek M, Vrojlik M, Hoss M, Damenha B, Friberg J, Koroschetz C, Skrikerud M (2015) From part design to part production – virtual hot forming engineering illustrated – focus material modelling. Proc of 5th Int Conf on Hot Sheet Metal Forming of High-Performance Steel, Toronto, pp. 463–470Google Scholar
  19. 19.
    Mori K, Maeno T, Yanagita Y (2016) Deep drawability and bendability in hot stamping of ultra-high strength steel parts. Key Eng Mater 716:262–269CrossRefGoogle Scholar
  20. 20.
    Maeno T, Mori K, Nagai T (2014) Improvement in formability by control of temperature in hot stamping of ultra-high strength steel parts. CIRP Ann Manuf Technol 63(1):301–304CrossRefGoogle Scholar

Copyright information

© Springer-Verlag London Ltd. 2017

Authors and Affiliations

  • Yuki Nakagawa
    • 1
  • Ken-ichiro Mori
    • 1
  • Tomoyoshi Maeno
    • 2
  1. 1.Department of Mechanical EngineeringToyohashi University of TechnologyToyohashiJapan
  2. 2.Division of Materials Science and Chemical Engineering, Faculty of EngineeringYokohama National UniversityYokohamaJapan

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