Microstructure and mechanical properties of similar and dissimilar laser welds of dp600 and dp1000 steel sheets used in the automotive industry

Year 2021, Volume: 5 Issue: 1, 8 - 14, 01.01.2021

Oğuz Tunçel , Hakan Aydın , Şükriye Çetin

https://doi.org/10.31127/tuje.649975

Cited By: 5

Abstract

Dual-phase (DP) steel sheets are the most widely used steel group in the automotive industry. When these steel sheets are used in car body components, welding is inevitably needed during the manufacturing process. Although the resistance spot welding (RSW) is the most widely used welding method in the automotive industry, the newly popular laser welding has gained more importance in the welding of these steel grades in recent years. In this work, the DP600 and DP1000 steel sheets were joined as double-sided with the pulsed Nd: YAG (Neodymium-doped Yttrium Aluminum Garnet (Y3Al5O12)) laser welding. Performing similar or dissimilar weld of DP steel sheets is an inevitable demand in the modern automotive industry. So, in this study similar (DP600-DP600, DP1000-DP1000) and dissimilar (DP600-DP1000) steel sheets were welded in the flat position with the butt joint. In order to evaluate welding performance, microstructural studies and mechanical tests were performed, and experiments carried out in this context include optical microscope studies, tensile tests and Vickers microhardness measurements. The tensile strength of the similar welded joints is a little bit lower than the base metals (BM). But, for dissimilar weld, the tensile strength is even lower than DP600-DP600 joint. And the microstructure of the welded joints are composed of martensite, retained austenite and bainite in the fusion zone and a mixture of martensite, bainite, ferrite, retained austenite and tempered martensite in heat affected zone (HAZ).

Keywords

Nd:YAG laser welding, DP600 steel, DP1000 steel, Mechanical properties, Microstructure

Supporting Institution

Bursa Uludağ Üniversitesi Bilimsel Araştırma Projeleri Birimi

Project Number

HDP(MH)-2017/47

Thanks

This study is supported by the Scientific Research Fund (BAP) of Uludag University (Project Contract No. HDP(MH)-2017/47)

References

• ASTM E8/E8M. (2009). Standard Test Methods for Tension Testing of Metallic Materials.
• Bandyopadhyay K, Panda S K, Saha P, Baltazar-Hernandez V H & Zhou Y N (2016). Microstructures and failure analyses of DP980 laser welded blanks in formability context. Materials Science and Engineering: A, 652, 250–263. DOI: 10.1016/j.msea.2015.11.091
• Di H, Sun Q, Wang X & Li J (2017) Microstructure and properties in dissimilar/similar weld joints between DP780 and DP980 steels processed by fiber laser welding. Journal of Materials Science & Technology, 33(12), 1561-1571. DOI: 10.1016/j.jmst.2017.09.001
• Dong D, Liu Y, Yang Y, Li J, Ma M & Jiang T (2014) Microstructure and dynamic tensile behavior of DP600 dual phase steel joint by laser welding. Materials Science & Engineering: A, 594, 17–25. DOI: 10.1016/j.msea.2013.11.047
• Fernandes F A O, Oliveira D F & Pereira A B (2017). Optimal parameters for laser welding of advanced high-strength steels used in the automotive industry. Procedia Manufacturing, 13, 219–226. DOI: 10.1016/j.promfg.2017.09.052
• Hazratinezhad M, Mostafa Arab N B, Sufizadeh A R & Torkamany M J (2012) Mechanical and metallurgical properties of pulsed neodymium-doped yttrium aluminum garnet laser welding of dual phase steels. Materials and Design, 33, 83–87. DOI: 10.1016/j.matdes.2011.06.070
• Hekmatjou H & Naffakh-Moosavy H (2018). Hot cracking in pulsed Nd:YAG laser welding of AA5456. Optics and Laser Technology, 103, 22–32. DOI: 10.1016/j.optlastec.2018.01.020
• Liu Y, Dong D, Wang L, Chu X, Wang P & Jin M (2015). Strain rate dependent deformation and failure behavior of laser welded DP780 steel joint under dynamic tensile loading. Materials Science and Engineering: A, 627, 296–305. DOI: 10.1016/j.msea.2014.12.103
• Mohammadpour M, Yazdian N, Yang G, Wang H P, Carlson B & Kovacevic, R (2018). Effect of dual laser beam on dissimilar welding-brazing of aluminum to galvanized steel. Optics and Laser Technology, 98, 214–228. DOI: 10.1016/j.optlastec.2017.07.035
• Parkes D, Xu W, Westerbaan D, Nayak S S, Zhou Y, Goodwin F, Bhole S & Chen D L (2013). Microstructure and fatigue properties of fiber laser welded dissimilar joints between high strength low alloy and dual-phase steels. Materials and Design, 51, 665–675. DOI: 10.1016/j.matdes.2013.04.076
• Saha D C, Westerbaan D, Nayak S S, Biro E, Gerlich A P & Zhou Y (2014) Microstructure-properties correlation in fiber laser welding of dual-phase and HSLA steels. Materials Science and Engineering: A, 607, 445–453. DOI: 10.1016/j.msea.2014.04.034
• Sharma R S & Molian P (2011) Weldability of advanced high strength steels using an Yb: YAG disk laser. Journal of Materials Processing Technology, 211(11), 1888–1897. DOI: 10.1016/j.jmatprotec.2011.06.009
• Sun Q, Di H S, Li J C & Wang X N (2016). Effect of pulse frequency on microstructure and properties of welded joints for dual phase steel by pulsed laser welding. Materials and Design, 105, 201–211. DOI: 10.1016/j.matdes.2016.05.071
• Wang J, Yang L, Sun M, Liu T & Li H (2016) Effect of energy input on the microstructure and properties of butt joints in DP1000 steel laser welding. Materials and Design, 90, 642–649. DOI: 10.1016/j.matdes.2015.11.006
• Węglowski M S, Kwieciński K, Krasnowski K & Jachym R (2009). Characteristics of Nd:YAG Laser Welded Joints of Dual Phase Steel. Archives of Civil and Mechanical Engineering, 9(4), 85–97. DOI: 10.1016/S1644-9665(12)60072-7
• Xia M, Biro E, Tian Z L & Zhou Y N (2008) Effects of heat input and martensite on HAZ softening in laser welding of dual phase steels. ISIJ International, 48(6), 809–814. DOI: 10.2355/isijinternational.48.809
• Yuce C, Tutar M, Karpat F, Yavuz N & Tekin G (2017). The effect of process parameters on the microstructure and mechanical performance of fiber laser-welded AA5182 aluminium alloys. Strojniski Vestnik/Journal of Mechanical Engineering, 63, 510–518.