On the Joint Mechanism of Ultrasonic Welding

Abstract

The joining mechanism of ultrasonic welding has not yet been explained. We have studied this mechanism by means of microscopic observation, X-ray diffraction, temperature measurement of joined parts, X-ray microanalysis etc. The results obtained were summarized as follows. (1) The sections of joined parts seemed to show that these parts are heated over the recrystallization temperature, according to the microscopic observation. None of intermetallic compounds and other phases were observed by electron microscopy. (2) The recrystallization patterns of X-ray diffraction were observed in the junctions between two different metal foils. Neither phases such as intermetallic compound nor other crystal structure were observed. (3) The temperature of joined parts was measured with an alumel-chromel thermo-couple and on oscillograph, and the temperature rise was found to be most affected by changing ultrasonic power. (4) X-ray microanalysis showed that the interatomic diffusion occurred at the ultrasonic bond between copper and titanium. (5) The joint strength of the bond was much influenced by the aging condition for the age-hardenable alloy; the joint strength of Cu-Be alloys treated at 350°C for 15∼30 min was about twice of that of unaged ones.