DOI QR코드

DOI QR Code

Hardness Estimation of Laser Welded Boron Steel Welds with the Carbon Equivalent

탄소 당량식을 이용한 고강도 보론강의 레이저 용접부 경도 예측

  • 전인환 (한국생산기술연구원 용접.접합그룹) ;
  • 김철희 (한국생산기술연구원 용접.접합그룹) ;
  • 김재도 (인하대학교 기계공학과 대학원)
  • Received : 2016.06.23
  • Accepted : 2016.08.16
  • Published : 2016.10.31

Abstract

The hardness of laser weldments has been predicted by using several carbon equivalent equations and estimation models. In this study, authors extended the model to boron steel sheets which are adopted for the hot press forming process. four kinds of boron steels with the strengths from 1500 MPa to 1900 MPa were considered and the hardness profiles of weldments was measured from the experiments of this study and the references. The traditional "Kaizu" equation could predict the hardness with an accuracy of -4.9% error although the Kaizu equation does not consider the boron content. Modified carbon equivalents were suggested by adding a term as like 5B or 14B into the Kaizu equation, and it could improve the accuracy of the prediction model.

Keywords

References

  1. T. Senuma, Physical metallurgy of modern high strength steel sheets, ISIJ international, 41(6) (2001), 520-532 https://doi.org/10.2355/isijinternational.41.520
  2. M. Takahashi, Development of high strength steels for automobiles, Nippon Steel Technical Report, No. 88 (2003), 2-6
  3. H. Karbasian and A. E. Tekkaya, A review on hot stamping, Journal of Materials Processing Technology, 210(15) (2010), 2103-2118 https://doi.org/10.1016/j.jmatprotec.2010.07.019
  4. I. Chang, Y. Cho, H. Park and D. So, Importance of Fundamental Manufacturing Technology in the Automotive Industry and the State of the Art Welding and Joining Technology, J. of Welding and Joining, 34(1) (2016), 21-25 (in Korean) https://doi.org/10.5781/JWJ.2016.34.1.21
  5. T.-K. Han, K.-Y. Lee and J.-S. Kim, Recent developments and weldability of advanced high strength steels for automotive applications, J. of Welding and Joining, 27(2) (2009), 13-18 (in Korean) https://doi.org/10.5781/KWJS.2009.27.2.013
  6. C.-H. Kim, J.-K. Choi, M.-J. Kang and Y.-D. Park, A study on the $CO_2$ laser welding characteristics of high strength steel up to 1500 MPa for automotive application, Journal of Achievements in Materials and Manufacturing Engineering, 39(1) (2010), 79-86
  7. C. Kim, M. Kang and Y. Park, Laser welding of Al-Si coated hot stamping steel, Procedia Engineering, 10 (2011), 2226-2231 https://doi.org/10.1016/j.proeng.2011.04.368
  8. M. Kang, C. Kim and J. Lee, Weld strength of laser-welded hot-press-forming steel, Journal of Laser Applications, 24(2) (2012), 022004 https://doi.org/10.2351/1.3699080
  9. M. Kang, C. Kim and S. Bae, Laser tailor-welded blanks for hot-press-forming steel with arc pretreatment, International Journal of Automotive Technology, 16(2) (2015), 279-283 https://doi.org/10.1007/s12239-015-0029-y
  10. M. Kang, Y.-M. Kim and C. Kim, Effect of heating parameters on laser welded tailored blanks of hot press forming steel, Journal of Materials Processing Technology, 228 (2016), 137-144 https://doi.org/10.1016/j.jmatprotec.2015.06.028
  11. C. Kang, T. Han, B. Lee and G. Chin, Hardness of laser welded AHSS with a strength over 600 MPa for automotive, Proceedings of 4th International Congress on Laser Advanced Materials Processing, (2006), Paper No. 06-276
  12. Y. Ito and K. Bessyo, Weldability Formula of High Strength Steels, Related to Heat-affected Zone Cracking, IIW Doc., (1968), IX-567-568
  13. N. Yurioka and H. Suzuki, Determination of necessary preheating temperature in steel welding, Welding Journal, 62(6) (1983), 147s-153s
  14. T. Kasuya and Y. Hashiba, Carbon equivalent to assess hardenability of steel and prediction of HAZ hardness distribution, Nippon Steel Technical Report, No. 95 (2007), 53-61
  15. S. Kaizu, Y. Shinbo and M. Ono, Relationship between vickers hardness of laser weld and chemical composition of steel sheets, Preprint of the National Meeting of JWS, 55 (1994), 118-119
  16. T. Taka and T. Yamamoto, The hardness of laser welded metal in steel sheets, Proceeding of 34th Material Processing Conference by Japan Laser Processing Society, 1995-3 (1995), 113-122
  17. M. Uchihara and K. Fukui, The Formability of Tailor Welded Blanks Using High Strength Steel Sheets, Quarterly J. of the Welding Society, 23(4) (2005), 541-548 https://doi.org/10.2207/qjjws.23.541
  18. M. Ono, A. Yoshitake and M. Omura, Laser weldability of high-strength steel sheets in fabrication of tailor welded blanks, Welding International, 18(10) (2004), 777-784 https://doi.org/10.1533/wint.2004.3321
  19. C.-Y. Kang, Hardening Characteristics and Carbon Equivalent in Laser Welds of Advanced High Strength Steels for Automobile, Journal of KWJS, 29(6) (2011), 15-25 (in Korean)
  20. T.-K. Han, B.-G. Park and C.-Y. Kang, Hardening characteristics of $CO_2$ laser welds in advanced high strength steel, Metals and Materials International, 18(3) (2012), 473-479 https://doi.org/10.1007/s12540-012-3014-2
  21. T.-J. Park, J.-W. Yu, J.-I. Kang, T.-K. Han, K.-K. Chin and C.-Y. Kang, Effect of B contents on hardness characteristic of disk laser beam welded CP steels, J. of Welding and Joining, 29(1) (2011), 107-114 (in Korean) https://doi.org/10.5781/KWJS.2011.29.1.107
  22. K. Fahlstrom, K.-A. Persson, J. K. Larsson and E. V. Ferrer, Evaluation of laser weldability of 1800 and 1900 MPa boron steels, Journal of Laser Applications, 28(2) (2016), 022426 https://doi.org/10.2351/1.4944102
  23. T. Taylor, G. Fourlaris, P. Evans and G. Bright, New generation ultrahigh strength boron steel for automotive hot stamping technologies, Materials Science and Technology, 30(7) (2014), 818-826 https://doi.org/10.1179/1743284713Y.0000000409
  24. Manganese-boron steels MBW$^{(R)}$ for hot forming, Thyssen-Krupp Steel Europe AG, November 2014 (https://www.thyssenkrupp-steel.com/en/products/sheetcoated-products/manganese-boron-steel/manganese-boron-steel.html)
  25. http://www.dvs-aft.de/AfT/AfT-Tagung/Files/Anlage_9_Praesentation-Laurenz-END.pdf (accessed 06/21/2016)
  26. M. Kang and C. Kim, Analysis of laser and resistance spot weldments on press-hardened steel, Materials Science Forum, 695(2011), 202-205 https://doi.org/10.4028/www.scientific.net/MSF.695.202
  27. J. Ion, K. E. Easterling and M. Ashby, A second report on diagrams of microstructure and hardness for heat-affected zones in welds, Acta Metallurgica, 32(11) (1984), 1949-1962 https://doi.org/10.1016/0001-6160(84)90176-7
  28. T. Kasuya, N. Yurioka and M. Okumura, Methods for predicting maximum hardness of heat-affected zone and selecting necessary preheat temperature for steel welding, Nippon Steel Technical Report, No. 65 (1995), 7-14
  29. N. Yurioka, Prediction of weld metal strength, IIW DOC (2003), Doc No. IX-2058-03
  30. N. Den Uijl, H. Nishibata, S. Smith, T. Okada, T. Van Der Veldt, M. Uchihara and K. Fukui, Prediction of post weld hardness of advanced high strength steels for automotive application using a dedicated carbon equivalent number, Welding in the World, 52(11-12) (2008), 18-29

Cited by

  1. Tensile–Shear Fracture Behavior Prediction of High-Strength Steel Laser Overlap Welds vol.8, pp.5, 2018, https://doi.org/10.3390/met8050365