Elektrik direnç punta kaynağı ile birleştirilen TBF/DP600 çeliklerinin mikroyapı ve mekanik özelliklerinin incelenmesi

Year 2022, Volume: 37 Issue: 2, 609 - 624, 28.02.2022

Hakan Aydın İmren Ozturk Yılmaz Abdullah Bilici

https://doi.org/10.17341/gazimmfd.808950

Cited By: 2

Abstract

In the study, the effects of welding parameters on microstructure and mechanical properties of electrical resistance spot welded TBF/DP600 steel sheets of 1.2 mm thickness were investigated. TBF steel used in the study was welded both with and without electro-galvanized. Microhardness measurements and tensile shear tests were taken as basis in determining the mechanical properties, while optical microscope was used for microstructural characterization. The nugget size of the spot-welded samples was determined by image processing technique, while the indentation depths at the electrode pressure points of the samples were measured by ultrasonic technique. It was observed from the fusion zone microstructure images that the two steels did not mix completely. Increasing the welding current and welding time increased the mixing ratio in fusion zone, expanded the heat affected zone and increased the nugget size, indentation depth and load bearing capacity. TBF steel was more affected by the thermal cycle during welding than DP600 steel. At high heat input, liquid metal embrittlement based microcrack formations initiating from the surface in the heat affected zone of galvanized TBF steels were observed, while corrosion started rapidly in the welding region of ungalvanized TBF steels. The highest hardness values were observed in ITAB on the TBF steel side. However, a significant softening occurred in the transition zone between the ITAB and base metal on the TBF steel side. The nugget size, indentation depth and load bearing capacity were found to be relatively higher in the galvanized TBF steel group. In dissimilar electrical resistance spot welded TBF/DP600 steel sheets having the same thickness, DP600 steel with lower strength has determined the welding strength. In high heat input during welding process, fractures are of the fusion zone button type with higher welding strength, while fractures are of partial fusion zone button type with lower welding strength in low heat input. If TBF steel is galvanized, relatively higher welding strength was obtained in the welding parameters that provide relatively lower heat input.

Keywords

TBF steel, DP600 steel, Electrical resistance spot welding, Welding parameters, Microstructure, Mechanical properties

Supporting Institution

Beyçelik Gestamp Otomotiv Sanayi A.Ş.

Project Number

-

Thanks

Bu çalışmaya Ar-Ge projesi kapsamında destek veren ve finanse eden Beyçelik Gestamp Otomotiv Sanayi A.Ş.’ne yazarlar olarak teşekkürlerimizi sunmaktayız.

References

• 1. Xie Z., Shang C., Wang X., Wang X., Han G., Misra R., Recent progress in third-generatipn low alloy steels developed under M3 microstructure control, International Journal of Minerals, Metallurgy and Materials, 27, 1-9, 2020.
• 2. McGuire N., Automotive industry lightens up, Tribology & Lubrication Technology; Park Ridge 73(11), 30-34, 36-38, 40-41, 2017.
• 3. Chebolu A., Automotive Lightweighting: A Brief Outline, In: Singh A., Sharma N., Agarwal R., Agarwal A. (eds) Advanced Combustion Techniques and Engine Technologies for the Automotive Sector. Energy, Environment, and Sustainability. Springer, Singapore, 2020. doi:10.1007/978-981-15-0368-9_12.
• 4. Kulkarni S., Edwards D.J., Parn E.A., Chapman C., Aigbavboa C.O., Cornish R., Evaluation of vehicle lightweighting to reduce greenhouse gas emissions with focus on magnesium substitution, Journal of Engineering, Design and Technology, 2018. doi:10.1108/JEDT-03-2018-0042.
• 5. Pervaiz M., Panthapulakkal S., Birat K.C., Sain M., Tjong J., Emerging trends in automotive lightweighting through novel composite materials, Materials Sciences and Applications, 7, 26–38, 2016. doi:10.4236/msa.2016.71004.
• 6. Aydin H., Tutar M., Davut K, Bayram A. Effect of welding current on microstructure and mechanical properties of 15% deformed TWIP steel joined with electrical resistance spot welding, Journal of the Faculty of Engineering and Architecture of Gazi University, 35(2), 803-817, 2020.
• 7. Ozturk Yilmaz I., Bilici A.Y., Aydin H., Microstructure and mechanical properties of dissimilar resistance spot welded DP1000–QP1180 steel sheets, Journal of Central South University, 26(1), 25-42, 2019.
• 8. Aydın H., Tutar M., Bayram A., Strain effect on the microstructure, mechanical properties and fracture characteristics of a TWIP steel sheet, Transactions of the Indian Institute of Metals, 71 (7), 1669-1680, 2018.
• 9. Tutar M., Aydın H., Bayram A., Effect of weld current on the microstructure and mechanical properties of a resistance spot-welded TWIP steel sheet, Metals, 7, 519, 2017.
• 10. Murata T., Hamamoto S., Utsumi Y., Yamano T., Futamura Dr. Y., Kimura T. Characteristics of 1180MPa Grade Cold-rolled Steel Sheets with Excellent Formability. Kobelco Technology Review, 35, 45-49, 2017.
• 11. Ebner S., Suppan C., Schnitzer R., Hofer C., Microstructure and mechanical properties of a low C steel subjected to bainitic or quenching and partitioning heat treatments, Materials Science and Engineering: A, 735(26), 1-9, 2018.
• 12. Nam N.D., Dong T.P., Nam T.T., Hai N.H., Khanh P.M., Influence of the Deformation on the Microstructure and Mechanical Properties of TBF Steel, Journal of the Korean Society for Precision Engineering, 37(8), 595-600, 2020.
• 13. Gibbs P.K., Strain Path Effect on Austenite Transformation and Ductility in TBF 1180 Steel, Theses and Dissertations, 7127, 2019.
• 14. Sugimoto K.I., Hojo T., Kobayashi J., Critical assessment 29: TRIP-aided bainitic ferrite steels, Materials Science and Technology, 33(17), 2005-2009, 2017.
• 15. Nasr El-Din H., Showaib E.A., Zaafarani N., Refaiy H., Structure-properties relationship in TRIP type bainitic ferrite steel austempered at different temperatures, International Journal of Mechanical and Materials Engineering, 12(3), 2017. doi:10.1186/s40712-017-0071-9.
• 16. De Moor E., Speer. J.G., Bainitic and quenching and partitioning steels, Automotive Steels, Design, Metallurgy, Processing and Applications, 289-316, 2017.
• 17. Sugimoto K.-I., Sato S.-H., Kobayashi J., Srivastava A.K., Effects of Cr and Mo on Mechanical Properties of Hot-Forged Medium Carbon TRIP-Aided Bainitic Ferrite Steels, Metals, 9, 1066, 2019.
• 18. Kimura T., Formability of TRIP Type Bainitic Ferrite Steel Sheet, Kobelco Technology Review, 30, 85-89, 2011.
• 19. Doruk E., Pakdil M., Çam G., Durgun İ., Kumru U.C., Otomotiv Sektöründe Direnç Nokta Kaynağı Uygulamaları, Mühendis ve Makina, 57(673), 48-53, 2016.
• 20. AWS D8.9M., Test Methods for Evaluating the Resistance Spot Welding Behavior of Automotive Sheet Steel Materials, An American National Standard, 2012.
• 21. Smithells C.J., Brandes E.A., Brook G.B., Metals Reference Book, 7th Ed. Oxford: Butterworth-Heinemann, 1992.
• 22. Wilzer J., Ludtke F., Weber S., Theısen W., The influence of heat treatment and resulting microstructures on the thermophysical properties of martensitic steels, Journal of Materials Science, 48(24), 8483–8492, 2013.
• 23. Frei J., Rethmeier M., Susceptibility of electrolytically galvanized dual-phase steel sheets to liquid metal embrittlement during resistance spot welding, Welding in the World, 62, 1031-1037, 2018.
• 24. Bhattacharya D., Liquid metal embrittlement during resistance spot welding of Zn-coated high-strength steels, Materials Science and Technology. 34, 1809-1829, 2018.
• 25. Barthelmie J., Schram A., Wesling V., Liquid metal embrittlement in resistance spot welding and hot tensile tests of surface-refined TWIP steels, IOP Conference Series: Materials Science and Engineering, 118:012002, 2016.
• 26. Hall E.O., The Deformation and Ageing of Mild Steel: III Discussion of Results, Proceedings of the Physical Society of London, 64 (9), 747–753, 1951.
• 27. Petch N.J., The Cleavage Strength of Polycrystals, Journal of the Iron and Steel Institute London, 173, 25–28, 1953.