徐振声
,
宫波
,
张彩碚
,
赖祖涵
金属学报
测定了各种氢含量对Ti-6Al-4V合金的流变应力(σ),应变速率敏感指数(m)和延伸率(δ)的影响,并对其微观结构进行了观察研究。结果表明,适量的氢对该合金在800—860℃范围内具有减少流变应力和降低超塑温度以及增加塑性的作用。
关键词:
氢
,
Ti-6Al-4V alloy
,
strain rate sensitivity
,
high temperature superplasticity
,
microstructure
L. X. Li and D. S. Peng (Department of Materials Science and Engineering
,
Central SouthUniversity of Technology
,
Changsha 410083
,
China)
金属学报(英文版)
The deformaton behavior of Ti - 6Al - 4V alloy under hot - working condition has been studied by compression testing in the temperature range 750 - 950℃ and strain rate range 0.05 - 15s -1. The flow stress decreases with the increase of temperature and with the decrease of strain rate. After a steep initial strain hardening, a flow softening occurs. This softening is mainly ascribed to the temperature rise and dynamic recmptallisation.By a simple extension, a classical sinushyperbolic constitutive equation can be used to describe the flow behavior of Ti - 6Al - 4V alloy. flow stress is described as a function of strain, strain rate and temperature. The parameters Q, n andaare the same at differ- ent deformation conditions, and A is a funciton of strain.
关键词:
Ti-6Al-4V alloy
,
null
,
null
Wenbo HAN
,
Kaifeng ZHANG
,
Guofeng WANG
,
Xiaojun ZHANG
材料科学技术（英文）
Superplastic forming and diffusion bonding (SPF/DB) is a well-established process for the manufacture of components almost exclusively from Ti-6Al-4V sheet material. The sandwich structure of Ti-6Al-4V alloy is investigated. The effects of the microstructure on the SPF/DB process were discussed. The microstructure at the interfaces and the distribution of thickness were researched.
关键词:
Superplastic forming
,
null
,
null
,
null
ZHANG Caibei BIAN Weimin LAI Zuhan GONG Bo Northeast University of Technology
,
Shenyang
,
China
金属学报(英文版)
The microstrueture and various hydrides precipitated in Ti-6A1-4V alloys containing hydrogen 0.16,0.58,0.87,1.49 wt-%,respectively,have been studied by means of TEM and X-ray diffraction.The Ti_3Al phase may precipitate when H over 0.58 wt-%.In the same time,the morphology of hydrides gradually changed from rugged sheets to narrow laths as H contents increased.The microstructure of highly H-doped alloys is obviously fine.A mas- sive hydride and the hydride with tetragonal lattice were observed in the specimen containing 1.49 wt-%H.The twin hydrides were found in the alloys with different H contents and the electron diffraction patterns of the twin hydrides can be served as a simple criterion for distin- guishing the cubic and tetragonal structures.
关键词:
titanium hydride
,
null
,
null
,
null
CHE Chengwei ZHANG Zhiming DONG Xianglin LIU Chengliang Harbin Institute of Technology
,
Harbin
,
150006
,
ChinaInstitute of Metal Research
,
Academia Sinica Shenyang
,
110015
,
China
材料科学技术（英文）
The behaviour of oxidation at elevated tem- peratures and fretting in the laser-alloyed layer of Ti-6Al-4V with the addition of Pr was studied. The results show that the addition of Pr changes the structure of oxide scale of Ti-6Al-4V,controls the short-range diffusion of oxygen to the scale/substrate interface and increases the adhe- sion and ductility of the scale,thus changing the oxidation kinetics and considerably reducing oxidation rate.The analysis of fretting test shows that the existence of high hardness layer in the al- loyed zone,fine dendrites perpendicular to the sur- face of the high hardness layer and the oxide scale produced during fretting at elevated temperatures are all beneficial to the improvement of wear resist- ance.
关键词:
laser modification
,
null
,
null
,
null
王学滨
,
杨梅
,
赵扬锋
稀有金属材料与工程
采用能描述非均质性的具有内部长度的梯度塑性理论推导了颈缩区域的非均匀的塑性拉伸应变.描述了颈缩区域的外形轮廓,并计算了当颈缩区域的体积保持不变时的颈缩区域的塑性伸长.由于外形轮廓已被确定,因而导出了真应力的表达式.目前得到的关于真应力-真应变曲线解析解的优越性在于:所需要的参数具有明确的物理意义,如:采用软化模量描述脆性;采用弹性模量描述弹性;采用特征长度描述材料的非均质性;模型中含有标定长度可用于研究结构的尺寸效应等.将目前得到的解析解与前人通过实验得到的钛及Ti-6Al-4V的真应力-真应变曲线进行了对比,验证了本文考虑微小结构效应及局部化颈缩的真应力-真应变曲线的解析解.另外,还发现Ti-6Al-4V的脆性及非均质性要高于商业纯钛.前人试验发现的局部化带在2种材料内部的传播速度的差异可以通过它们具有不同的脆性得到解释.
关键词:
真应力-真应变曲线
,
微结构
,
钛
,
Ti-6Al-4V合金
,
尺寸效应
,
颈缩
,
应变局部化
S.Y. Gao
,
Y.Z. Zhang
,
L.K. Shi
,
B.L. Du
,
M.Z. Xi
,
H.Z. Ji
,
null
,
null
,
null
,
null
,
null
,
null
,
null
,
null
,
null
,
null
,
null
金属学报(英文版)
Laser direct deposition (LDD) of metallic components is an advanced technology of combining CAD/CAM (computer aided design/computer aided manufacturing), high power laser, and rapid prototyping. This technology uses laser beam to melt the powders fed coaxially into the molten pool by the laser beam to fabricate fully dense metallic components. The present article mainly studies the LDD of Ti-6Al-4V alloy, which can be used to fabricate aircraft components. The mechanical properties of the Ti-6Al-4V alloy, fabricated by LDD, are obtained using the tension test, and the oxygen content of used powders and deposited specimens are measured. In the present article, it can be seen that the mechanical properties obtained using this method are higher than the ones obtained by casting, and equal to those got by wrought anneal. One aircraft part has been made using the LDD process. Because of this aircraft part, with sophisticated shape, the effect of the laser scanning track on the internal soundness of the deposited part was discussed.
关键词:
laser direct deposition
,
null
,
null
Yong LIU
,
Jingchuan ZHU
,
Zhongda YIN
,
Mingwei LI
材料科学技术（英文）
The effect of triple annealing on stress relaxation of Ti-6Al-4V alloy as well as the microstructure after stress relaxation were studied. The results showed that triple annealing treatment enhanced the resistance of stress relaxation performance, and when the temperature was rising, this effect became notable. The stress relaxation deformation mechanism is of dislocation creep at 400℃ and recovery creep at 600℃.
关键词:
Triple annealing
,
null
,
null
