Effect of Friction Welding Condition and Weld Faying Surface Properties on Tensile Strength of Friction Welded Joint between Pure Titanium and Pure Copper

Abstract

This paper describes the effect of the friction welding condition and the weld faying surface properties on the tensile strength of the friction welded joint between pure titanium (Ti) and pure copper (OFC). The joint strength of the joint, which was made with the weld faying surface of the Ti side specimen finished with a surface grinding machine, was investigated. The joint did not have 100% efficiency and OFC side fracture regardless of the friction welding conditions. When the joint was made with a friction pressure of 75 MPa, the joint efficiency was approximately 64% regardless of the forge pressures, and all joints fractured at the weld interface, although that efficiency exceeded that of the joints made with other friction pressures. To improve the joint efficiency, one was made with a Ti side specimen whose weld faying surface was finished by buff polishing. The joint efficiency was increased to approximately 85%, although the joint fractured at the weld interface. Moreover, a joint at a friction pressure of 75 MPa with a forge pressure of 270 MPa or higher was obtained with an OFC side fracture, although it did not achieve 100% efficiency. The fact that the joint did not fracture at the OFC base metal was due to the mechanically mixed layer at the weld interface that depended on the maximum height of the Ti side weld faying surface. To clarify the reason why the joint did not achieve 100% joint efficiency, the tensile strength of the OFC base metal with the addition of various compressive stresses was investigated. When the compressive stress was higher than the yield stress of the OFC base metal, its tensile strength was lower than that without a compressive load. Moreover, the tensile strength along the radial direction of the OFC base metal was also slightly lower than that of the longitudinal direction. Hence, the fact that the joint did not also achieve 100% efficiency was due to the decrease in the tensile strength of the OFC base metal by the Bauschinger effect and the difference of the anisotropic property with as-manufactured condition.

Effects of friction welding conditions on tensile strength of friction welded joint between 5052 Al alloy and pure copper

“…5. A similar mechanically mixed layer was also observed even in several friction welded joints for dissimilar materials combination as reported by many researchers (Ruge, et al, 1986;Yilmaz, et al, 1996;Fuwano, et al, 2000;Straffelini, et al, 2004;Meshram, et al, 2007;Arivazhagan, et al, 2008;Kimura, et al, 2011) in addition to CP-Al/OFC joint (Aritoshi, et al, 1991;Kimura, et al, 2015). Figure 8 shows the cross-sectional appearances of the weld interfaces of joints at various friction times.…”

“…7b). Hence, it is desirable to be set of an opportune friction time which generate less mechanically mixed layers of the joint because that layer will be affected to the joint strength (Aritoshi, et al, 1991;Kimura, et al, 2011Kimura, et al, , 2015 in addition to the IMC interlayer as reported by some researchers (Nakanishi, et al, 1976;Lee, et al, 2005;Chen, et al, 2006;Saeid, et al, 2010;Wei, et al, 2016). However, all joints fractured from the weld interface as shown in Fig.…”

“…In this instance, the sufficient data could be obtained in order to understand the temperature distribution of the radius direction in the weld interface and the temperature change at those locations, although the temperature on the weld interface during the friction process was able to estimate as those or higher. All weld faying surfaces of specimens were polished with a surface grinding machine before joining in order to eliminate the effect of surface roughness on the mechanical properties of dissimilar material joints (Hasui and Matsui, 1983;Futamata, et al, 1989;Fuji et al, 1994Fuji et al, , 1995Kimura, et al, 2005Kimura, et al, , 2011.…”

Joining phenomena and tensile strength of friction welded joint between pure aluminum and pure copper

“…The materials were machined to 12 mm diameters for the weld faying (contacting) surface (referred to as faying surface). All faying surfaces of specimens were polished with a surface grinding machine before joining in order to eliminate the effect of surface roughness on the mechanical properties of dissimilar material joints (Fuji, et al, 1994;Kimura, et al, 2005cKimura, et al, , 2011b.…”

“…Furthermore, the authors also clarified the joining mechanism and the joint mechanical properties of friction welded joint for some dissimilar material joints as following combinations: Al-system materials and low carbon steel (LCS) (Kimura, et al, 2009a(Kimura, et al, , 2009b(Kimura, et al, , 2013, Cu-system materials and LCS (Kimura, et al, 2009c(Kimura, et al, , 2009d, pure Ti and LCS (Kimura, et al, 2014), and pure Cu and pure Ti (Kimura, et al, 2011a(Kimura, et al, , 2011b. If combinations of dissimilar materials such as Al-system materials and Cu-system materials can be joined using the same welding method as that shown in previous reports (Kimura, et al, 2002a(Kimura, et al, , 2002b(Kimura, et al, , 2002c(Kimura, et al, , 2003a(Kimura, et al, , 2003b2005a;2005b, 2009a, 2009b, 2009c, 2009d, 2011a, 2011b, 2013, 2014, the joining mechanism will be clarified. In particular, to clarify the relationship between joining phenomena and tensile strength of that combination joint is strongly important, because that will be estimated for expansion in the use of the electricity industry field.…”