Formation mechanism of abnormal coarse grains on weld seam of extruded ZK60 alloy and the effects on mechanical properties

The abnormal grain growth of ZK60 alloy during porthole die extrusion was studied. The results indicated that the abnormal grains (AGs) discontinuously formed along the weld seam, due to the growth priority of some grains and the restriction on normal grain growth. The grain boundaries with large misorientation angles owned high energy and mobility, and the different sub-grain structures between AGs and normal grains (NGs) provided the driving...