Study on Ultrasonic Welding (2 nd Report)

On Multiple Spot Welding, Spot Welding of Copper Alloys and of Titanium or zirconium to Steels

Abstract

In this study an investigation was made in many ways about multiple spot welding as a preliminary research of ultrasonic seam welding and about spot welding as to the relationship between aging phenomena and joining properties, and lining of titanium or zirconium to steel.
In multiple spot welding it is needlees to say that joining properties are affected by ultrasonic power, tip pressure, joining time, shapes of tip and head of anvil and so on, but under the same joining condition they are fairly affected by the pitch (distance from spot center to spot center) and directien of tip motion. Pitch should be chosen properly so that the part joined already may not be interfered by the next joining.
In the joining of Cu-Be alloy (2.1% Be) water cooled from 750°C to Ag-Cu Alloys (90, 75, 60 Ag), the best joining properties were obtained in the case of Cu-Be alloy aged at 350°C for 15 to 30 min.. In this case, tensile shear strength of joint was about twice as large as that of material (as received, 1/2H) to Ag-Cu alloy.
No good joining properties were obtained in the case of being aged at 350°C for less than 10 min. or at 450°C for 60 min..
Comparing the joining properties of a material (as received, 1/2 H) to the same one with that of a material water cooled from 750°C to the same one, the former was better.
About joining properties of Ag-Cu alloys, the one that contained more silver was better.
Joining titanium or zirconium to mild steel or 18-8 stainless steel could be made by choosing suitahie ultrasonic welding condition.
Under the same joining condition still better joining part can be obtained by electrolytically polishing or zinc plating that surface to be joined of mild steel or 18-8 stainless steel, or putting in silver insert.
Mild steel and 18-8 stainless steel of which structures were the more unstable showed the better joining properties.