材料期刊网

DEVELOPMENT OF CONSTITUTE EQUATIONS FOR Ti-6Al-4V ALLOY UNDER HOT-WORKING CONDITION

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

氢对Ti-6Al-4V合金的高温增塑作用

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

超塑性变形Ti-6Al-4V合金中接近重位点阵取向α晶界滑动机制的TEM研究

赵林若 , 张少卿 , 颜呜皋

材料研究学报

用TEM 研究了超塑性变形Ti_(-6)Al_(-4)V 合金中接近重位点阵取向(near-CSL)的α晶界,发现在部分晶界上晶界位错(GBD:)的衍衬象变得漫散,但仍然保持线状特征;某些GBD 有局部的分解和束集反应;在α晶界与晶内亚结构的交界处,GBS 通过束集反应形成新的组态;构成晶界坎的各个界面上,GBD 排列的位向各不相同,晶界坎可向晶内发射点阵位错。

关键词: 超塑性 , Ti-6Al-4V alloy , grain boundary sliding

Hydrogen Treatment of Cast Ti-6Al-4V Alloy

ZHANG Shaoqing PAN Feng Institute of Aeronautical Materials , Beijing , 100095 , China.

材料科学技术（英文）

This paper presents the results of an investiga- tion of the effect of hydrogen treatment on microstructures and tensile and low cycle fatigue properties of a Ti-6Al-4V cast alloy.The phase transformation and the refining mechanism of the cast microstructure during the process of hydrogen treatment were studied.It was found that after hydrogen treatment,the coarse Widmansttten structure of the as-cast Ti alloy was transformed into a very fine and equiaxed α+β microstructure without any GBα phase.The tensile strength and ductility and the low cycle fatigue life of the hydrogen treated specimens were significantly im- proved.

关键词: Ti-6Al-4V , null , null , null , null , null

Damage of Ti-6Al-4V Alloy Induced by Hypervelocity Impact

Journal of Spacecraft and Rockets

The impact of macro- and microdamage behaviors of Ti-6Al-4V alloy has been examined using a two-stage light gas gun. Disks with thicknesses from 2 to 20 mm cut from a forged and annealed Ti-6Al-4V alloy bar with the diameter of 70 mm, and plates cut from a rolled Ti-6Al-4V alloy sheet with a thickness of 1 mm, were employed as single- and multilayer targets, respectively. The impact velocities of the spherical steel, 4.0-mm-diam projectiles, ranged from 1 to 4 km/s. For the impacted targets, the crater shape and dimension, microstructures and microhardness distributions in the vicinity of craters were characterized by complementary techniques such as optical microscopy, scanning electron microscopy, and Vickers microhardness measuring. Based on the experimental results, the penetration resistance of the annealed Ti-6Al-4V alloy and the critical impact velocity to form the debris clouds in the Ti-6Al-4V alloy sheet were obtained.

关键词: ballistic plug formation;dynamic deformation;titanium-alloy;behavior;penetration;velocity;targets;metals

Superplastic Forming and Diffusion Bonding for Sandwich Structure of Ti-6Al-4V Alloy

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

Apatite formation on anodized Ti-6Al-4V alloy in simulated body fluid

Metals and Materials International

Titania layers were successfully prepared on the surfaces of Ti-6Al-4V alloy via anodic oxidation in H(2)SO(4) or Na(2)SO(4) solutions at room temperature. The titania layers consisted of pure rutile or a mixture of anatase and rutile structures after the Ti-6Al-4V alloy had been anodized in 1.0 M H(2)SO(4) solution at 150 V or 0.5M Na(2)SO(4) solution at 100 or 130 V. Good apatite-forming ability was demonstrated in simulated body fluid. However, surface layers with mainly titanium metallic phase or a pure anatase structure did not possess the ability to induce apatite formation. Anodic oxidation is an effective method to prepare bioactive Ti-6Al-4V alloy that can be used as an artificial bone substitute under load-bearing applications.

关键词: alloys;anodization;surface;x-ray diffraction;apatite;bioactive titanium metal;chemical surface-treatment;heat-treatments;oxide-films;oxidation;coatings;ability;bone;ca

Effect of Triple Annealing Treatment on Stress Relaxation of Ti-6Al-4V Alloy

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

EFFECT OF HYDROGEN ON HIGH TEMPERATURE PLASTICITY OF Ti-6Al-4V ALLOY

XU Zhensheng GONG Bo ZHANG Caibei LAI Zuhan Northeast University of Technology , Shenyang , China

金属学报(英文版)

The effects of various hydrogen contents on the flow stress(σ),strain rate sensitivity expo- nent(m)and the tensile elongation(δ)of Ti-6Al-4V alloy were studied.The microstructure of the alloy was also investigated.The results indicate that,a suitable amount of hydrogen in the alloy can reduce the flow stress in the temperature range 800—860℃. Consequently,the superplastic temperature can be decreased and the ductility improved.

关键词: Hydrogen , null , null , null

Research on Laser Direct Deposition Process of Ti-6Al-4V Alloy

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