Ying Yan
,
Wan-Peng Deng
,
Zhan-Feng Gao
,
Jing Zhu
,
Zhong-Jun Wang
,
Xiao-Wu Li
金属学报(英文版)
doi:10.1007/s40195-016-0373-6
To explore the coupled effect of temperature T and strain rate ε˙ε˙ on the deformation features of AZ31 Mg alloy, mechanical behaviors and microstructural evolutions as well as surface deformation and damage features were systematically examined under uniaxial tension at T spanning from 298 to 523 K and ε˙ε˙ from 10-4 to 10-2 s-1. The increase in T or the decrease in ε˙ε˙ leads to the marked decrease in flow stress, the appearance of a stress quasi-plateau after an initially rapid strain hardening, and even to the occurrence of successive strain softening. Correspondingly, the plastic deformation modes of AZ31 Mg alloy transform from the predominant twinning and a limited amount of dislocation slip into the enhanced non-basal slip and the dynamic recrystallization (DRX) together with the weakened twinning. Meanwhile, the cracking modes also change from along grain boundaries (GBs) and at twin boundaries (TBs) or the end of twins into nearby GBs where the DRX has occurred. The appearance of a stress quasi-plateau, the formation of large-sized cracks nearby GBs, and the occurrence of continuous strain softening, are intimately related to the enhancement of the non-basal slip and the DRX.
关键词:
AZ31
,
Mg
,
alloy
,
Uniaxial
,
tension
,
Temperature
,
Strain
,
rate
,
Deformation
,
Damage
,
Twinning
Wei JIN
,
Ying YAN
,
Jian WANG
,
Mingzhou CAO
,
Rui YANG
材料科学技术（英）
The mechanical behavior and the effect of pre-strain on recovery behavior of Ti50Ni47Fe3 (at. pct) alloy were investigated systematically by tensile and recovered tests accompanied by electrical resistance measurement. Ti50Ni47Fe3 alloy has different deformation behaviors at different temperature ranges, the deformation curves in different temperature range can be classified into four kinds. The start temperature of recovery increases with the increase of pre-strain. There exists an optimal deformation condition, at which the specimen exhibits maximum free recovery strain. With increasing pre-strain the recovery stress increases and reaches the maximum at 8% pre-strain. R-phase to parent transition offered about 0.2% recovery strain. With pre-strain increasing the recovery stress increases and reaches to the maximum at 8% pre-strain. The recovery stress is corresponding with the critical stress of stress-induced martensitic transformation.
关键词:
Deformation
,
null
,
null
,
null
,
null
Hongwei JIANG
,
Chunfeng LI
,
Haiping YU
,
Zhiheng ZHAO
材料科学技术（英）
Calculation of magnetic pressure is the basis of application of electromagnetic forming (EMF). This paper carries out a numerical simulation of magnetic pressure under the influence of die by means of finite element method. The analysis model of electromagnetic bulging with die is created by using ANSYS, and the distribution of magnetic pressure acting on the tube and the die is obtained. The differences between EMF and other technologies and the effect of die on tube formability are analyzed. The die has important influence upon the calculation accuracy. The simulating conclusions with different discharge energy and current frequency are verified through the technologic tests. The distribution of magnetic pressure acting on the tube agrees well with the measurements of the deformed tube.
关键词:
Electromagnetic bulging
,
null
,
null
,
null
Jinxia LI
,
Xianghua LIU
,
Guodong WANG
材料科学技术（英）
The relationships among the deformation, texture and deep drawing properties of IF steel were investigated. By adopting double cold rolling (DCR) technology, the deep drawing property has been developed evidently. With the aid of orientation distribution function (ODF) analysis, it was found that the main reason for good property is the counterbalance in intensity of the ideal texture component {111}<011> and {111}<112>.
关键词:
Texture
,
null
,
null
,
null
Ping YANG
材料科学技术（英）
Channel die compression and initial textures are used to activate different deformation mechanisms in a fine-grained magnesium alloy AZ31. The $\sigma$-$\varepsilon$ curves, microstructures and, particularly, textures are analyzed to reveal different deformation mechanisms and to compare with those of coarse grained samples. Dominant double-prismatic slip, {101ˉ2} twinning and basal slip are detected in three types of samples, respectively, which is similar to those of coarse grained samples. The detrimental effect of shear band formation or {101ˉ1} twinning is limited in fine grained microstructure. In addition to the higher flow stress at low temperature an early decrease in flow stress at higher temperature is also found in fine-grained samples in comparison with their coarse-grained counterparts. This softening is ascribed to the early dynamic recrystallization or grain boundary glide.
关键词:
Magnesium alloy
,
null
,
null
,
null
