Abstract
Friction welding of different diameter bars is very important for practical applications. That is affected by the asymmetrical thermal conduction of friction heat and deformation, compared with the symmetrical behaviour of the friction welding of equi-diameter bars.
In this study, friction welding phenomenon of different diameter bars of strainless steel SUS 304 was studied.
The diameter of one bar was fixed as a standard, and the diameter of another bar was changed from the same diameter of the standard bar to large diameter enough to be considered as a plate, then the pair was friction welded. During friction welding, temperature of friction surface, friction torque and brun-off behaviour were examined.
Effect of the ratio of diameter of each bar, d/d0 (d0=standard diameter, d=comparative diameter) on these friction welding behaviour was studied.
Experimental results were as follows;
(1) From the observation of the macrophotograph of joints, deformation of comparative diameter bar decreases with increase of d/d0=1.75 or above. This is the same state of stud to plate welding. (2) Steady state temperature of friction surface rises up with increase of d/d/, and it is close to the constant value with the d/d0 value of more than 2.
(3) As for the friction torque, the initial torque is not so affected by d/d0, but steady torque and terminal torque increase with increase of d/d0 becoming to constant when d/d0 is more than 1.75.
(4) Burn-off behaviours, for example, burn-off rate and total upset decrease with increase of d/d0, and these also become constant for d/d0 above 1.75. These constant value is larger than half of the values at d/d0=1.
