Effect of friction time on flash shape and axial shortening of linear friction welded 45 steel

The influence of friction time on the flash (upset metal) shape and axial shortening during linear friction welding of 45 steel under an appropriate welding condition was examined. It was found that a sound weld with the fine structures could be formed as the friction time not less than 3 s. The axial shortening was exponentially increased with increasing the friction time. The periodical ridges presented in the flash were formed through the reciprocating motion and expelling of the plasticized materials. The flash in the friction direction presents an undulating-ribbon structure, while that in the vertical direction looks like a little curly swirl. The curved ridges were caused by the non-uniform extrusion rates of materials in the middle and edge resulting from the non-uniform temperatures.