A study of the mechanisms involved in initial friction process of continuous drive friction welding

The effects of the welding conditions on the initial friction process of continuous drive friction welding are investigated using 20-Mild steel. The results show that the friction interface will sequentially experience three typical friction behaviours of abrasion, slide and stick before the initial peak torque. The torque in slide stage shows a platform feature, which transforms to stick stage with a rapidly increasing feature of the torque. As the friction pressure increases from 15 to over 60 MPa, the initial joining location (i.e. corona bond) shifts from one-fourth of the specimen radius (1/4R) towards 1/2R. The maximum surface temperatures show initial slow rising, platform and rapid rising features before the highest temperature appears, which is corresponding to the interface friction status of abrasion, slide or stick. The initial joining location virtually coincides with the location where the maximum temperature is attained.