Ultrasonic Welding between Mild Steel Sheet and Al-Mg Alloy Sheet

Transcription

1 [ 25 p (2007)] ** *** ** Ultrasonic Welding between Mild Steel Sheet and Al-Mg Alloy Sheet by WATANABE Takehiko, SAKUYAMA Hideko and YANAGISAWA Atushi Ultrasonic welding between SS400 mild steel sheet and aluminum alloy sheet containing magnesium (A5052) was conducted. In this study, authors investigated the influence of ultrasonic welding condition on the mechanical properties and the interface microstructure of a joint, and examined the effect of an insert metal to improve the joint strength. The main results obtained in this study are as follows. It was possible to ultrasonically weld SS400 mild steel sheet and A5052 sheet. When the clamping force was varied keeping the welding time constant for 1s, the joint strength showed the maximum at the clamping force of 588N and it decreased with the clamping force because the frictional action at the interface decreased with it. When the clamping force was kept constant at 588N and the welding time was varied, the joint strength reached the maximum at the welding time of 2.5s, and the strength of the joint welded for 3s decreased due to the formation of Fe 2 Al 5 intermetallic compound at the interface. Using an insert metal of commercially pure aluminum successfully improved the joint strength and the strength of the joint welded at the welding time of 3s was about three times that of the joint without an insert metal. Key Words: Ultrasonic welding, Mild steel sheet, Al-Mg alloy sheet, Joint strength, Microstructure of interface, Insert metal, Improvement of joint strength ) 2) 3 9) 10) 11 12) Al Mg * ** Member, Niigata University, Graduate School of Science and Technology *** Student member, Niigata University, Graduate School of Science and Technology 0.8 mm SS400 Al 1.2 mm Al Mg A5052 H24 Al 2.84at%MgA mm Al A1050 H24A1050 SS400, A5052 A MPa 250 MPa 106 MPa SS400 A mm 100 mm A mm 25 mm SS400 Ra 0.58 m A5052 A1050 Ra 0.34 m 15 khz 53 m peak to peak 10 mm 10 mm 10 mm 10 mm 0.8 mm Fig. 1 A5052

2 240 Al-Mg Fig. 2 U SEM EDS SS400 Fig mm K A5052 A s 343 N 1764 N Fig N 588 N 412 N Al 13 16) SS400 A N A5052 A N 1176 N A5052 Fig N 588 N A N 540 m 588 N 460 m 14) SS400 Fig s 343 N N 882 N 400 Fig. 2 Schematic illustration for the tensile test of a joint. Fig. 1 Schematic illustration of the apparatus for ultrasonic welding. Enlarged part of the specimens shows the location of a thermocouple to measure the interface temperature. Fig. 3 Relation between tensile load of a joint and clamping force.

3 Fig. 5 Temperatures of a specimen welded at various clamping force. Fig. 4 The appearances of scratches on A5052 surface formed by a welding tip with pyramidal projections. (a): Clamping force of 588N, (b): Clamping force of 1176N SS N 1.0 s SS400 SEM Fig. 6 (a) (b) (c) (b) (c) (b) W S (c) W EP W, S EP 13 14) W Weld S Scrape A5052 EP Electrolytic Polish SS400 W S EP Fig mm 20 17) 1000 Fig. 6 Fracture surface of SS400 (a). Photographs (b) and (c) are SEM micrographs of white part (b) and dark part (c) in the photograph of (a), respectively. Fig N W W Fig N 0.5 s 3.0 s

4 242 Al-Mg Fig. 7 Area ratio of EP, S and W region in fracture surface of SS400 vs. clamping force. Fig. 8 Relation between tensile load of a joint and welding time. Fig. 9 Area ratio of EP, S and W region in fracture surface of SS400 vs. welding time. Fig. 10 Macrostructure and SEM micrograph of the interface of a joint welded under the conditions of 3s welding time and 588N clamping force. SEM micrograph shows the intermetallic compound formed at the interface. Fig s 3.0 s SS400 Fig. 7 Fig. 9 W 3.0 s 3.0 s Fig N 3.0 s SEM 1 m EDS 26.9at%Fe 69.8at%Al 3.3at%Mg Fe Al 18) Fe 2 Al s 3.0 s 3.3 A1050 Mg A5052 A Al Mg 13) Fig N 2.5 s SS400 EDS MgO Mg Mg A ks Mg Mg MgO 13) HV 79.0 HV 80.7 A5052 SS N

5 Fig. 11 Fracture surface of SS400 in the joint made under the conditions of 2.5s welding time and 588N clamping force. Fig. 12 The influence of preheating A5052 on the tensile load of a joint. Fig. 13 The influence of preheating A5052 on the area ratio in the fracture surface of SS s SS400 W S EP Fig. 12 Fig. 13 A5052 Mg W Mg Mg A1050 A5052 SS400 A1050 A mm 25 mm 10 mm 588 N 0.5 s 3.0 s SS400 W S EP Fig. 14 Fig. 15 Fig s 3.0 s 300% 1800 N SS400 W 80% A1050 Fig. 14 Relation between tensile load of a joint welded using an insert metal and clamping force. Fig. 15 Area ratio of EP, S and W region in fracture surface of SS400 in a joint welded using an insert metal. Fig N 3.0 s (a) A1050 SS400 (b) A1050 A5052 (a) A s Fig SEM Al Mg Al Fe Fe 2 Al 5 10) Mg A1050

6 244 Al-Mg Fig. 16 SEM micrographs of the joint interface welded using an insert metal at the welding time of 3s. (a): Interface of SS400/A1050, (b): Interface of A1050/A5052 Fe 2 Al 5 Fig. 16(b) A1050 A SS400 A SS400 A s 588 N 2588 N 2.5 s 3.0 s Fe 2 Al 5 3 A1050 SS400 A s 300% 1) For example, M. Aritoshi and K. Okita: Friction welding of dissimilar metals, J. of Japan Welding Society, Vol.71, No.6, 2000, (in Japanese) 2) For example, T. Kohno: Production of Al/SUS Clad material Using Vacuum Roll Bonding and its Characteristics, J. of Japan welding Society, Vol.71, No.6, 2000, ) T. Watanabe, A. Yanagisawa and H. Takayama: Bonding of steel and aluminum alloy by interfacial active adhesion bonding method, Preprints of the National meeting of Japan Welding Society, Vol.71, 2002, (in Japanese) 4) T. Watanabe and H. Takayama: Joining of Steel to Aluminum Alloy by Interface-Activated Adhesion Welding, Materials Science Forum, Vols , 2003, ) T. Watanabe, A. Yanagisawa and H. Takayama: Solid state welding aluminum alloy to steel using a rotating pin, Quarterly J. of Japan Welding Society, Vol.22, No.1, 2004, (in Japanese) 6) M. Fukumoto, M. Tsubaki, Y. Shimoda and T. Yasui: Welding between ADC12 and SS400 by means of friction stirring, Quarterly J. of Japan Welding society, Vol.22, No.2, 2004, (in Japanese) 7) T. Watanabe, et al: Friction stir welding of aluminum alloy to steel, Welding Journal, Vol.83, No.10, 2004, 277S-282S. 8) K. Kimapong and T. Watanabe: Lap Joint of A5083 Aluminum Alloy and SS400 Steel by Friction Stir Welding, Materials Transactions, Vol.46, No.4, 2005, ) K. Kimapong and T. Watanabe: Effect of Welding Process Parameters on Mechanical Properties of FSW Lap Joint between Aluminum Alloy and Steel, Materials Transactions, Vol.46, No.10, 2005, ) T. Watanabe, Y. Doi A. Yanagisawa and S. Konuma: Resistance spot welding of mild steel toal-mg alloy, Quarterly J. of Japan Welding Society, Vol.23, No.3, 2005, (in Japanese) 11) T.Watanabe and A.Yoneda et al, A Study on Ultrasonic Welding of Dissimilar Metals, 1st report and 2nd report, Quarterly J. of Japan Welding Society, Vol.17, No.2, 1999, (in Japanese) 12) T.Watanabe and A.Yoneda et al, A Study on Ultrasonic Welding of Dissimilar Metals, 2nd report, Quarterly J. of Japan Welding Society, Vol.17, No.2, 1999, (in Japanese) 13) M. Hiraishi and T. Watanabe: Effect of magnesium on ultrasonic weldability of Al-Mg alloy, Quarterly J. of Japan Welding Society, Vol.20, No.4, 2002, (in Japanese) 14) M. Hiraishi and T. Watanabe: Improvement of ultrasonic weld strength for Al-Mg alloy by adhesion of alcohol, Quarterly J. of Japan Welding Society, Vol.21, No.2, 2003, (in Japanese) 15) Electric Industries Association of Japan: Ultrasonic Engineering, Corona Publishing Co., 1995, (in Japanese) 16) N.E.Weare, J.N. Antonevich, R.E. Monrore: Fundamental studies of ultrasonic welding, Welding Journal, Vol.37, No. 8, 1960, 331s- 341s. 17) T. Sato et al edited: Materials Inspection Methods, Japan Institute of Metals, 1959, 28. (in Japanese) 18) T. B. Masalski et al edited: Binary Phase Diagrams, ASM, 1996, CD.