Dissimilar titanium/aluminum friction stir welding lap joints by experiments and numerical simulation

Abstract

Dissimilar lap joints were produced by friction stir welding (FSW) out of Ti6Al4V titanium alloy and AA2024 aluminum alloy sheets. The joints, welded with varying tool rotation and feed rate, were studied by analyzing the maximum shear strength, Vickers microhardness and optical observations. A dedicated numerical model, able to take into account the presence of the two different alloys, was used to highlight the effects of the process parameters on temperature distribution, strain distribution, and material flow. The combined analysis of experimental measurements and numerical predictions allowed explaining the effects of tool rotation and feed rate on the material flow. It was found that tool rotation had a larger impact on the joint effectiveness with respect to feed rate. A competition between material mixing and heat input occurs with increasing tool rotation, resulting in higher joint strength when lower values of tool rotation are used.

Keywords

Finite element method (FEM) / Ti6Al4V / AA2024 / Friction stir welding (FSW) / Lap joint

References

[1] Leyens C, Kocian F, Hausmann J, et al. Materials and design concepts for high performance compressor components. Aerosp Sci Technol, 2003, 7(3): 201-210.

[2] Elias KL, Daehn GS, Brantley WA, et al. An initial study of diffusion bonds between superplastic Ti-6Al-4V for implant dentistry applications. J Prosthet Dent, 2007, 97(6): 357-365.

[3] Sujata M, Bhargava S, Sangal S. On the formation of TiAl₃ during reaction between solid Ti and liquid Al. J Mater Sci Lett, 1997, 16(13): 1175-1178.

[4] Wang GX, Dahms M, Leitner G, et al. Titanium aluminides from cold-extruded elemental powders with Al-contents of 25-75 at% Al. J Mater Sci, 1994, 29(7): 1847-1853.

[5] Wei Y, Li J, Xiong J, et al. Joining aluminum to titanium alloy by friction stir lap welding with cutting pin. Mater Charact, 2012, 71: 1-5.

[6] Dressler U, Biallas G, Alfaro MU. Friction stir welding of titanium alloy TiAl6V4 to aluminium alloy AA2024-T3. Mater Sci Eng A, 2009, 526(1–2): 113-117.

[7] Wilden J, Bergmann JP. Manufacturing of titanium/aluminium and titanium/steel joints by means of diffusion welding. Weld Cut, 2004, 3(5): 285-290.

[8] Yao W, Wu A, Zou G, et al. Structure and forming process of the Ti/Al diffusion bonding joints. Xiyou Jinshu Cailiao Yu Gongcheng/Rare Met Mater Eng, 2007, 36(4): 700-704.

[9] Gao M, Chen C, Gu Y, et al. Microstructure and tensile behavior of laser arc hybrid welded dissimilar Al and Ti alloys. Materials, 2014, 7(3): 1590-1602.

[10] Elrefaey A, Tillmann W. Solid state diffusion bonding of titanium to steel using a copper base alloy as interlayer. J Mater Process Technol, 2009, 209(5): 2746-2752.

[11] Kim YG, Fujii H, Tsumura T, et al. Three defect types in friction stir welding of aluminum die casting alloy. Mater Sci Eng A, 2006, 415(1–2): 250-254.

[12] Nandan R, DebRoy T, Bhadeshia HKDH. Recent advances in friction-stir welding: process, weldment structure and properties. Prog Mater Sci, 2008, 53(6): 980-1023.

[13] Khodir SA, Shibayanagi T. Friction stir welding of dissimilar AA2024 and AA7075 aluminum alloys. Mater Sci Eng B: Solid-State Mater Adv Technol, 2008, 148(1–3): 82-87.

[14] Liu D, Xin R, Zheng X, et al. Microstructure and mechanical properties of friction stir welded dissimilar Mg alloys of ZK60-AZ31. Mater Sci Eng A, 2013, 561: 419-426.

[15] Li B, Zhang Z, Shen Y, et al. Dissimilar friction stir welding of Ti-6Al-4V alloy and aluminum alloy employing a modified butt joint configuration: influences of process variables on the weld interfaces and tensile properties. Mater Des, 2014, 53: 838-848.

[16] Wu A, Song Z, Nakata K, et al. Interface and properties of the friction stir welded joints of titanium alloy Ti6Al4V with aluminum alloy 6061. Mater Des, 2015, 71: 85-92.

[17] Zhang Z, Shen Y, Feng X, et al. Dissimilar fiction stir welding of titanium alloy and aluminum alloy employing a modified butt joint configuration. Hanjie Xuebao/Trans China Weld Inst, 2016, 37(5): 28-32.

[18] Chen YC, Nakata K. Microstructural characterization and mechanical properties in friction stir welding of aluminum and titanium dissimilar alloys. Mater Des, 2009, 30(3): 469-474.

[19] Chen YH, Ni Q, Ke LM. Interface characteristic of friction stir welding lap joints of Ti/Al dissimilar alloys. Trans Nonferrous Met Soc China (Engl Ed), 2012, 22(2): 299-304.

[20] Chen ZW, Yazdanian S. Microstructures in interface region and mechanical behaviours of friction stir lap Al6060 to Ti-6Al-4V welds. Mater Sci Eng A, 2015, 634: 37-45.

[21] Buffa G, Hua J, Shivpuri R, et al. A continuum based FEM model for friction stir welding: model development. Mat Sci Eng A: Struct, 2006, 419(1–2): 389-396.

[22] Gök K, Aydin M. Investigations of friction stir welding process using finite element method. Int J Adv Manuf Technol, 2013, 68(1–4): 775-780.

[23] Abbasi M, Bagheri B, Keivani R. Thermal analysis of friction stir welding process and investigation into affective parameters using simulation. J Mech Sci Technol, 2015, 29(2): 861-866.

[24] Buffa G. Joining Ti6Al4V and AISI 304 through friction stir welding of lap joints: experimental and numerical analysis. Int J Mater Form, 2016, 9(1): 59-70.

[25] Buffa G, Fratini L, Micari F et al (2012) On the choice of tool material in friction stir welding of titanium alloys. In: Transactions of the North American Manufacturing Research Institution of SME, pp 785–794

[26] Buffa G, Ducato A, Fratini L. FEM based prediction of phase transformations during friction stir welding of Ti6Al4V titanium alloy. Mater Sci Eng A, 2013, 581: 56-65.

[27] Buffa G, Ducato A, Fratini L (2013) Dissimilar material lap joints by friction stir welding of steel and titanium sheets: process modeling. In: AIP Conference Proceedings, pp 491–498