Grain coarsening in semi-solid state and tensile mechanical properties of thixoformed AZ91D-RE

For thixoforming to be possible, the microstructure of the starting material must be non-dendritic, which can be ob- tained by the strain induced melt activation （SIMA） route. Based on the SIMA route, as-cast AZ91D alloy with the addition of yttrium was deformed by cyclic closed-die forging （CCDF）....

Full description

Saved in:
Bibliographic Details
Published in:Journal of rare earths 2013-03, Vol.31 (3), p.319-326
Main Authors: WANG, Liping, CHEN, Tian, JIANG, Wenyong, FENG, Yicheng, DONG, Wenxue, WANG, Zhiwei, LIANG, Zhenqiang, ZHU, Yan
Format: Article
Language:English
Subjects:
AZ91D镁合金
Coarsening
Elongation
Grains
magnesium alloy
Magnesium base alloys
Mechanical properties
microstructure
Ostwald熟化
partial remelting
Rare earth metals
rare earths
Semi-solid processing
thixoforming
Ultimate tensile strength
半固态触变成形
应变诱发熔体激活法
拉伸力学性能
晶粒粗化
极限抗拉强度
极限拉伸强度
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:For thixoforming to be possible, the microstructure of the starting material must be non-dendritic, which can be ob- tained by the strain induced melt activation （SIMA） route. Based on the SIMA route, as-cast AZ91D alloy with the addition of yttrium was deformed by cyclic closed-die forging （CCDF）. Microstructure evolution of CCDF formed AZ91D-RE alloy during partial remelting were investigated. Furthermore, the mechanical properties of thixoformed AZ91D-RE magnesium alloy components were also studied. The results showed that prolonged holding time resulted in grain coarsening and the improvement in degree of spheroidization. The coarsening behaviour of solid grains in the semi-solid state obeyed Ostwald ripening mechanism. The coarsening rate constant of CCDF formed AZ91D-RE during partial remelting was 324 um3/s at 550 ℃. The value of yield strength, ultimate tensile strength and elongation to fracture of four-pass CCDF formed AZ91D-RE magnesium alloy were 214.9, 290.5 MPa and 14%, respectively. Then the four-pass CCDF formed alloys were used for thixoforming. After holding at 550 ℃ for 5 min, the values of yield strength, ultimate tensile strength and elongation to fracture of thixoformed component were 189.6 MPa, 274.6 MPa and 12%, respectively. However, prolonged holding time led to remarkable decrease in mechanical properties ofthixo- formed components.
ISSN:1002-0721
2509-4963
DOI:10.1016/S1002-0721(12)60279-8