WELDING RESEARCH three-sheet aluminum alloy RSWs. Cracks will form and propagate in the interior of the LCGZ or along the interface of SCGZ and LCGZ during the tensile-shear test. 5) The following equations are proposed to predict the critical nugget diameter required to ensure PO failure mode during the tensile-shear tests of three-sheet aluminum alloy spot weld joints (DC )Types I&II&III = 3tID Pf HFL HLCGZ cos��IF cos��PO where t is thickness of the middle sheet, tID is the sheet thickness considering the indentation, Wis the width of the sheet, P is the porosity factor, f is a constant coefficient, IF is the rotation angle when the joint fails in the IF mode, PO is the rotation angle when the joint fails in the PO mode, HFL is the hardness of the failure location, HLCGZ is the hardness of the columnar grain with a large secondary dendrite arm spacing, HBM is the hardness of the base metal, HPMZ is the hardness of the partially melted zone, and HEGZ is the hardness of the equiaxed grain zone. 6) The joint design has a significant effect on the failure mode transition. For three equal-thickness sheet RSWs, the critical weld nugget diameter (DC) required for obtaining a PO failure mode during the tensile-shear test increases in order of Type III, Types I and II, and Type IV. For three unequalthickness sheet RSWs, the DC may be controlled by the thickness of the middle sheet for the joint design of pure shear. This paper preliminarily investigates the failure behavior of triplethin sheet aluminum alloy resistance spot welds under tensile-shear loads. There are many contents that need further research. More thickness combinations should be tested to verify the proposed analytical mode. The failure behaviors of spot welds under other loading conditions, such as coach peel and cross tension, are important issues and need to be studied. The failure behaviors of spot welds of other materials, such as 5000 series alloys, or dissimilar materials, such as 5000 series alloys to 6000 series alloys, are valuable to pursue. Acknowledgments This research is supported by the National Nature Science Foundation of China (Grants 51405334 and 51275342). References 1. Chao, Y. J. 2003. Ultimate strength and failure mechanism of resistance spot weld subjected to tensile, shear, or combined tensile/shear loads. Journal of Engineering Materials and Technology 125: 125–132. 2. Pouranvari, M., and Marashi, S. P. H. 2012. Failure behavior of three-steel sheets resistance spot welds: effect of joint design. Journal of Materials Engineering and Performance 21(8): 1669–1675. 3. Shen, J., Zhang, Y. S., Lai, X. M., and Wang, P. C. 2011. Modeling of resistance spot welding of multiple stacks of steel sheets. Materials & Design 32: 550–560. 4. Harlin, N., Jones, T. B., and Parker, J. D. 2002. Weld growth mechanisms during resistance spot welding of two and three thickness lap joints. Science and Technology of Welding and Joining 7(1): 35–41. 5. Harlin, N., Jones, T. B., and Parker, J. D. 2003. Weld growth mechanism of resistance spot welds in zinc coated steel. Journal of Materials Processing Technology 143–144: 448–453. 6. Nielsen, C. V., Friis, K. S., Zhang, W., and Bay, N. 2011. Three-sheet spot welding of advanced high-strength steels. Welding Journal 90(2): 32-s to 40-s. 7. Pouranvari, M., and Marashi, S. P. H. 2011. Critical sheet thickness for weld nugget growth during resistance spot welding of three-steel sheets. Science and Technology of Welding and Joining 16(2): 162–165. 8. Lei, Z. Z., Kang, H. T., and Liu, Y. G. 2011. Finite element analysis for transient thermal characteristics of resistance spot welding process with three sheets assemblies. Procedia Engineering 16: 622–631. 9 Ma, N., and Murakawa, H. 2010. Numerical and experimental study on nugget formation in resistance spot welding for three pieces of high strength steel sheets. Journal of Materials Processing Technology 210: 2045–2052. 10. Katayama, S., and Kawahito, Y. 2010. Evolution of laser welding to dissimilar materials joining. Transactions of JWRI 39(2): 268–269. 11. Li, Y., Yan, F. Y., Luo, Z., Chao, Y. J., Ao, S. S., and Cui, X. T. 2015. Weld growth mechanisms and failure behavior of threesheet resistance spot welds made of 5052 aluminum alloy. Journal of Materials Engineering and Performance 24(6): 2546–2555. 12. Hongyan, Z., and Jacek, S. 2012. Resistance Welding: Fundamental and Applications, 2nd ed. Boca Raton, CRC Press. 13. Kou, S. 2003. Welding Metallurgy, 2nd ed. New Jersey, John Wiley & Sons, Inc. 14. Drebushchak, V. A. 2008. The Peltier Effect. Journal of Thermal Analysis and Calorimetry 91(1): 311–315. 15. Li, B. Q. 2002. Research on the numerical Simulation of the Process for Aluminum Alloy Resistance Spot Welding and Energy Analysis. PhD Dissertation. Tianjin, Tianjin University. 16. Pouranvari, M., Marashi, S. P. H., and Mousavizadeh, S. M. 2010. Failure mode transition and mechanical properties of similar and dissimilar resistance spot welds of DP600 and low carbon steels. Science and Technology of Welding and Joining 15(7): 625–631. 17. Marya, M., Wang, K., Hector, L. G., and Gayden, X. H. 2006. Tensile-shear forces and fracture modes in single and multiple weld specimens in dual-phase steels. Transactions of the ASME Journal of Manufacturing Science and Engineering 128(1): 287–298. 18. Han, L., Thornton, M., Boomer, D., and Shergold, M. 2011. A correlation study of mechanical strength of resistance spot welding of AA5754 aluminium alloy. Journal of Materials Processing Technology 211: 513–521. 19. Sun, X., Stephens, E. V., Davies, R. W., Khaleel, M. A., and Spinella, D. J. 2004. Effects of fusion zone size on failure modes and static strength of aluminum resistance spot welds. Welding Journal 83(11): 308-s to 318-s. 20. Pouranvari, M., and Marashi, S. P. H. 2011. Failure mode transition in AHSS resistance spot welds. Part I. Controlling factors. Materials Science and Engineering A 528(29–30): 8337–8343. 21. Pouranvari, M., Asgari, H. R., Mosavizadch, S. M., Marashi, P. H., and Goodarzi, M. 2007. Effect of weld nugget size on overload failure mode of resistance spot welds. Science and Technology of Welding and Joining 12(3): 217–225. 22. Pouranvari, M., and Marashi, S. P. H. 2012. Failure mode transition in AISI 304 resistance spot welds. Welding Journal 91(11): 303-s to 309-s. 23. VandenBossche, D. J. 1977. Ultimate strength and failure mode of spot welds in high strength steels. SAE Technical Paper 770214: 955–966. 24. Pouranvari, M., and Marashi, S. P. H. 2013. Critical review of automotive steels spot welding: Process, structure and properties. Science and Technology of Welding and Joining 18(5): 361–403. 25. Kissell, J. R., and Ferry, R. L. 2002. Aluminum Structures: A Guide to Their Specifications and Design, 2nd ed. New York, John Wiley & Sons, Inc. (DC )Type IV = 3 4 (��tHPMZ ��tHBM ) + 3 2 1 2 tHBM �� �� 2 tHPMZ ������ ������ 2 + 4+ 3 fHEGZ + 4+ 3 fHLCGZ ������ ������ W 2 tHBM + 3W 4 tfHBM ������ ������ ��fHEGZ + ��fHLCGZ 490-s WELDING JOURNAL / DECEMBER 2016, VOL. 95
Welding Journal | December 2016
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