2004 Volume 22 Issue 2 Pages 233-239
The present paper describes the effects of inner diameter on friction torque during friction stage of friction welding with mild carbon steel pipes whose outer diameter is 16 mm. The experimental conditions included inner diameter (i.e., pipe thickness) and friction speed. A conventional friction welding machine was used to join all specimens.
The following conclusions are given.
(1) When various pipes with different inner diameters were welded under same friction welding conditions, the friction torque curves for each pipe is different in the first phase of the friction stage, particularly in the wear stage. That is, the initial torque and elapsed time for initial torque decreased with increasing inner pipe diameter.
(2) The initial torque and elapsed time for initial torque decreased with increasing inner pipe diameter when the joints of solid bars to pipes were welded under the same friction welding conditions.
(3) When pipes of the same inner diameter were welded:
a) the friction torque in the first phase of the friction stage varied due to sparks flashing from the welded interface, and
b) the initial torque and elapsed time for initial torque increased with decreasing friction speed.
(4) The result in (3) indicates that the seizure temperature at low relative speeds at the welded interface was lower than that at high relative speed.