Abstract:An extensive investigation has been carried out on the friction stir welded butt joint consisting of a
2219MCS ring and a 2219C10S barrelꎬ and the effect of welding speed and the location of the 2219MCS ring on the
microstructureꎬ microhardness distribution and mechanical properties of the butt joint has been systematically analyzed
in this paper. The results showed that the 2219MCS ring whether located in the advancing side or retracting side is the
weak link of the joint due to the original coarse grain. The microhardness distribution of the joint showed the typical
“W” type with the TMAZ of the 2219MCS ring the lowest. The optimized investigation results showed that the per ̄
formance of the joint with the 2219MCS ring located in the retracting side is more than the joint with the 2219MCS
ring located in the advancing side. When the welding speed is 180 to 220 mm/ min and the 2219MCS ring located in
the retracting sideꎬ the room temperature mechanical strength can be up to 330 MPaꎬ the low temperature strength 420
MPaꎬ and the ductility all more than 3.5%. The face bending angle can reach 180° without crack on the jointꎬ but
some cracks occurred on the parent metal of the 2219MCS ring. The back bending performance is so poorꎬ and the
crack occurred and spreaded along the TMAZ of the 2219MCS ring.