The activation of twinning and texture evolution during bending of friction stir welded magnesium alloys

The present study aims to investigate the twinning behavior and texture evolution during bending of a friction stir welded (FSW) AZ31 Mg alloy. Two kinds of three-point bending tests (designated as Surface test and Base test) were applied at room temperature. Strong texture-dependent twinning characteristics were revealed after bending. The largest numbers of extension twins were observed in SZ-side after Surface test and in SZ-center after Base test. The texture-dependent twinning activity was well explained by the calculated Schmid factor based on a speculated local stress state. Some extension twins were likely connected with each other and formed twin chain or twin band, and most of the neighboring twins present a high geometrical compatibility factor (larger than 0.8), implying that the local strain compatibility played an important role in the formation of connected twins.