Effect of pre-rolling path on mechanical properties of rolled ZK60 alloys

Pre-cold rolling with low reductions(<3%)was used to improve the mechanical properties of rolled ZK60 plates.The effects of rolling path on mechanical properties were investigated in detail.Both pre-cold rolling along the transverse direction(TD)and pre-cold rolling along the normal direction(ND)can increase the yield strength.However,pre-cold rolling along the TD is more effective than pre-cold rolling along the ND in improving the comprehensive mechanical properties.After pre-cold rolling to 3%reduction,the sample rolled along the TD and the sample rolled along the ND have similar tensile yield strength(~270 MPa).However,the former has a higher compressive yield strength,lower yield asymmetry and larger toughness than the latter.Moreover,pre-cold rolling can also enhance precipitation hardening effect.However,aging treatment cannot further improve the yield strength of pre-cold rolled samples.Finally,the related mechanism is discussed.

Influence of free-end torsion on compressive behavior of extruded AZ31 rod at various temperatures

The influence of free-end torsion on compressive behavior of an extruded AZ31 rod at various temperatures was studied.Pre-torsion generates a high density of dislocations and a large number of{1012}twins in the matrix,which can largely enhance the compressive yield strength at RT and 100℃.However,with increasing temperature,hardening effect via pre-torsion gradually decreases.When the compressive temperature reaches 300℃,pre-torsion reduces the compressive yield strength.Moreover,initial dislocations and twins via torsion help to refine the sub-structure and accelerate the continuous dynamic recrystallization during compression at 200℃.Thus,twisted sample exhibits more rapid flow softening behavior than the as-extruded sample at 200℃.When compressed at 300℃,the twins and dislocations via torsion were largely eliminated during the holding time,and the discontinuous dynamic recrystallization was enhanced.It is found that the compression curves of twisted sample and as-extruded sample tended to be coincident at 300℃.Related mechanisms were discussed in detail.