The mechanical properties and deformation mechanism of semi-continuously casting and as-extruded AZ70 magnesium alloys in a wide range of grain sizes(from 14 to 103μm)were investigated at 653 K and 1×10-3s -1.It...The mechanical properties and deformation mechanism of semi-continuously casting and as-extruded AZ70 magnesium alloys in a wide range of grain sizes(from 14 to 103μm)were investigated at 653 K and 1×10-3s -1.It is discovered that with reducing grain size,flow stress is weakened and plasticity is improved and even superplasticity exhibits.SEM and OM were used to clarify the deformation mechanism.It is suggested that dynamic recrystallization(DRX)is the coordination deformation mechanism of grain boundary sliding(GBS)for coarse grain,and cavity and intracrystalline slip are the coordination deformation mechanisms of GBS for fine grain.展开更多
To evaluate and predict flow stress and set up hot forging process of AZ70 magnesium alloy,hot compression tests of AZ70 magnesium alloy were carried out on Gleeble 1500D thermo-mechanics tester at 300-420℃and strain...To evaluate and predict flow stress and set up hot forging process of AZ70 magnesium alloy,hot compression tests of AZ70 magnesium alloy were carried out on Gleeble 1500D thermo-mechanics tester at 300-420℃and strain rates of 0.001-1 s- 1 with different compression degrees.It is indicated that temperature and strain rate are the main factor affecting the flow stress and microstructure.Stress increases but average grain size decreases with temperature decreasing and strain rate increasing.The stress model,constituted by introducing temperature-compensated strain rate,the Zener-Hollomon parameter,has a good fitness with the proof stress value under the experimental condition.The reciprocal of grain size at true strain of 1.0 has a linear relation with natural logarithm of Z parameter,and the correlation coefficient,R=0.95,is very significant by examination.The hot deformation activation energy Q of AZ70 alloy is 166.197 kJ/mol by calculation.展开更多
基金Project(2008CB617509)supported by the National Basic Research Program of ChinaProject(30870634)supported by the National Natural Science Foundation of China
文摘The mechanical properties and deformation mechanism of semi-continuously casting and as-extruded AZ70 magnesium alloys in a wide range of grain sizes(from 14 to 103μm)were investigated at 653 K and 1×10-3s -1.It is discovered that with reducing grain size,flow stress is weakened and plasticity is improved and even superplasticity exhibits.SEM and OM were used to clarify the deformation mechanism.It is suggested that dynamic recrystallization(DRX)is the coordination deformation mechanism of grain boundary sliding(GBS)for coarse grain,and cavity and intracrystalline slip are the coordination deformation mechanisms of GBS for fine grain.
基金Project(204085)supported by Key Project of Educational Ministry of China
文摘To evaluate and predict flow stress and set up hot forging process of AZ70 magnesium alloy,hot compression tests of AZ70 magnesium alloy were carried out on Gleeble 1500D thermo-mechanics tester at 300-420℃and strain rates of 0.001-1 s- 1 with different compression degrees.It is indicated that temperature and strain rate are the main factor affecting the flow stress and microstructure.Stress increases but average grain size decreases with temperature decreasing and strain rate increasing.The stress model,constituted by introducing temperature-compensated strain rate,the Zener-Hollomon parameter,has a good fitness with the proof stress value under the experimental condition.The reciprocal of grain size at true strain of 1.0 has a linear relation with natural logarithm of Z parameter,and the correlation coefficient,R=0.95,is very significant by examination.The hot deformation activation energy Q of AZ70 alloy is 166.197 kJ/mol by calculation.
