Mechanical and metallurgical properties of titanium alloy Friction Stir Welded butt joints

• Autorzy: Fratini L. , Buffa G.

Warianty tytułu

PL

Mechaniczne i metalurgiczne własności stopów tytanu łączonych metodą zgrzewania tarciowego z mieszaniem

• Języki publikacji: EN

Abstrakty

EN

Friction Stir Welding (FSW) is a solid state welding process patented in 1991 by TWI; initially adopted to weld aluminum alloys, is now being successfully used also for magnesium alloys, copper and steels. The wide diffusion the process is having is due to the possibility to weld both materials traditionally considered difficult to be welded or "unweldable" by traditional fusion welding processes due to peculiar thermal and chemical material properties, and complex geometries as sandwich structures and straightening panels. Additionally, the process allows welding a wide range of sheet thickness (up to 50mm) avoiding typical fusion welding processes defects, like cavities and porosities, with no shielding gas, filling material or joint preparation. Recently, research is focusing on titanium alloys thanks to the high interest that such materials are getting from the industry due to the extremely high strength-weight ratio together with good corrosion resistance properties. Welding of titanium alloys by traditional fusion welding techniques presents several difficulties due to high material reactivity resulting in bonding with oxygen, hydrogen, and nitrogen with consequent embrittlement of the joint. In this way FSW can represent a cost effective and high quality solution. In the paper the effect of two different tool geometries on welding temperatures acquired during FSW of the widely commercially diffused Ti-6A1-4V alloy is analyzed. Experimental results are compared with temperatures numerically calculated by means of a FEM Lagrangian model of the process developed by the authors. The study of the temperatures reached at the varying of the tool dimensions leads to a deeper knowledge of the process as well as to the possibility to predict the microstructural evolutions occurring during the weld and dramatically influencing the mechanical properties of the obtained joints.

PL

Zgrzewanie tarciowe z mieszaniem (FSW) jest metodą zgrzewania materiałów w stanie stałym opatentowaną w 1991 roku przez TWI. Początkowo wykorzystywana była do zgrze-wania stopów aluminium, a obecnie z powodzeniem stosowana również do stopów magnesu, miedzi i stali. Niniejsza praca skupia się natomiast na zgrzewaniu stopów tytanu. Stopy te są bardzo obiecującym materiałem charakteryzującym się wysoką wartością współczynnika wytrzymałości w stosunku do masy oraz odpornością na korozję. Zgrzewanie stopów tytanu metodami tradycyjnymi niesie ze sobą kilka trudności spowodowanych łatwością wchodzenia materiału w reakcję z tlenem, wodorem i azotem, powodując tym samym kruchość zgrzewu. Alternatywą jest metoda FSW, która jest tanim i zapewniającym wysoką jakość rozwiązaniem. W artykule przedstawiono analizę wpływu prędkości kątowej narzędzia na osiąganą temperaturę podczas zgrzewania metodą FSW stopu Ti-6A1-4V. Uzyskane wyniki badań eksperymentalnych przeanalizowano pod kątem otrzymywanych własności w obszarze zgrzewu.

Słowa kluczowe

EN

friction stir welding; titanium; temperature

• Wydawca: Wydawnictwa AGH
• Czasopismo: Computer Methods in Materials Science
• Rocznik: 2011
• Tom: Vol. 11, No. 1
• Strony: 167--172
• Opis fizyczny: Bibliogr. 13 poz., rys.

Twórcy

autor

Fratini L.

autor

Buffa G.

• Dipartimento di Ingegneria Industriale Universita di Palermo Viale delle Scienze,

Bibliografia

• Buffa, G., Campanile G., Fratini, L., Prisco, A., 2009, Friction stir welding of lap joints: Influence of process parameters on the metallurgical and mechanical properties, Mater. Sci. and Eng. A, 519, 19.
• Fratini, L., Buffa, G., Micari, F., Shivpuri, R, 2009, On the material flow in FSW of T-joints: Influence of geometrical and tecnological parameters, Int. J. of Adv. Manuf. Technol, 44, 570.
• Fratini, L., Buffa, G., Shivpuri, R., 2010, Mechanical and metallurgical effects of in process cooling during friction stir welding of AA7075-T6 butt joints, Acta Mater., 58, 2056.
• Fratini, L., Micari, F., Buffa, G., Ruisi, V.F., 2010, A new fixture for FSW processes of Titanium alloys, Annals of CIRP, 59/1: 271-274.
• Guerra, M., Schmidt, C, McClure, L.C., Murr, L.E., Nunes, A.C., 2003, Flow patterns during friction stir welding, Mater Charact, 49: 95-101.
• Lee, W.-B., Lee, C.-Y., Chang, W.-S., Yeon, Y.-M., Jung, S.-B., 2005, Microstructural investigation of friction stir welded pure titanium, Materials Letters, 59(26):3315-3318.
• Liu, H.J., Fujii, H., Maeda, M., Nogi, K., 2003, Tensile properties and fracture locations of friction-stir-welded joints of 2017-T351 aluminum alloy, J. of Mat. Proc. Tech., 142, 692-696.
• Mironov, S., Zhang, Y., Sato, Y.S.,Kokawa, H., 2008, Development of grain structure in (3-phase field during friction stir welding of Ti-6A1-4V alloy, Scripta Materialia, 59 (1), 27-30.
• Pasta, S., Reynolds, A.P., 2008, Residual stress effects on fatigue crack growth in a Ti-6A1-4V friction stir weld, Fatigue and Fracture of Engineering Materials and Structures, 31 (7), 569-580.
• Rhodes, C.G., Mahoney, M.W., Bingel, W.H., Spurling, R.A., Bampton, C.C., 1987, Effects of Friction Stir Welding on Microstructure of 7075 Aluminum, Scripta Materialia, 36, 69-75.
• Winter, E.F.M., Sharp, M.L., Nordmark, G.E., Banthia, V.K., 1990, Design considerations for aluminium spaceframe automotive structures, SAE technical series, Report No 905178.
• Zhang, Y., Sato, Y.S., Kokawa, H., Park, S.H.C., Hirano, S, 2008, Microstructural characteristics and mechanical properties of Ti-6A1-4V friction stir welds, Materials Science and Engineering A, 485 (1-2), 448-455.
• Zhang, Y., Sato, Y.S., Kokawa, H.,Park, S.H.C., Hirano, S.. 2008, Stir zone microstructure of commercial purity titanium friction stir welded using pcBN tool, Materials Science and Engineering A, 488 (l-2),25-30.