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1.
Ti-6Al-4V (Ti-6-4) sheets of two different grain sizes were exposed to time and temperature conditions representative of superplastic
forming (SPF). The influence of SPF conditions on oxidation rates was evaluated in terms of weight gain, α-case depth, and
microhardness profile. Differences in the response are related to the difference in grain size between the two lots of Ti-6-4.
Fine grain Ti-6Al-4V exhibits faster oxygen diffusion in all three areas examined in this study, weight gain, α-case thickness,
and increased microhardness depth. The differences were found to be significant relative to diffusion analysis and processing
during manufacturing. Results from this work support reduced temperature SPF using fine grain material and the accompanying
benefits in manufacturing superplastic parts.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
2.
Superplastic forming (SPF) of titanium 6Al-4V, with a standard grain size of about 8 μm, is typically performed between 900°
and 920°C. Verknaya Salda Metallurgical Production Association in Russia has developed a fine-grain version of the 6–4 alloy,
with a grain size of about 1 μm, which can be superplastically formed at around 775° C. Since this material diffusion bonds
to itself as well as other standard grain size titanium alloys at this temperature, super-plastically formed and diffusion
bonded (SPF/DB) hardware can be produced. There are several advantages to using this lower forming temperature, including
a smaller amount of alpha case developed on parts, longer press platen and heater life, and less oxidation of the tool surface.
This fine-grained 6–4 material is currently being used in the production of SPF and SPF/DB aerospace components due to these
advantages. 相似文献
3.
Radhakrishna B. Bhat Seshacharyulu Tamirisakandala Daniel B. Miracle 《Journal of Materials Engineering and Performance》2004,13(6):653-659
Addition of boron to titanium alloys produces fine TiB whiskers in situ with excellent thermal stability and good chemical
compatibility with the matrix. These whiskers stabilize a fine-grain microstructure by restricting grain growth at high temperatures
in the β phase field. The hot deformation behavior in the β phase field (temperature range 1050–1200 °C) of Ti-6Al-4V alloys
modified with two different levels of B additions (1.6 and 2.9 wt.%) produced by powder metallurgy was investigated using
hot compression tests in the strain rate range of 10−3 to 10−1 s−1 and hot tensile tests at a nominal strain rate of 6×10−4 s−1. The β phase exhibits superplasticity, which occurs due to stabilization of a fine-grain microstructure by the TiB. Matrix
grain boundary sliding and β/TiB interface sliding appear to contribute to the β superplasticity. The ability to achieve superplasticity
at higher temperatures enable lower flow stresses, improved chemical homogeneity, and high strain rate capability due to enhanced
accommodation processes.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
4.
Reinforced ceramic dies for superplastic forming operations 总被引:2,自引:0,他引:2
Daniel G. Sanders 《Journal of Materials Engineering and Performance》2004,13(6):753-757
Ceramic dies have been developed to meet the need for a dimensionally stable tool, which can withstand the temperatures (425
to 950 °C) and high forming pressures (up to 7 MPa) that are required for superplastic forming (SPF), superplastic forming
with diffusion bonding (SPF/DB), and hot sizing of metal parts. With the improvements that have been made to strengthen fused
silica based ceramics, the performance of ceramic tools is slowly closing in on meeting the same forming complexity as corrosion-resistant
steel (CRES) dies can achieve. Boeing has successfully superplastically formed jet engine wide chord fan blades using ceramic
dies, and many production aircraft parts are being built with Boeing’s patented ceramic die technology.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
5.
Peter Comley 《Journal of Materials Engineering and Performance》2007,16(2):150-154
Most parts made by superplastic forming (SPF) have been formed at an optimum strain rate. The rate is selected to give the
best SPF properties of the material. However, it has been proposed that multi-rate forming, where an initial high strain rate
is successively reduced as the part is strained, can be used to make high strain parts in a much shorter time than traditional
SPF forming. This paper examines the performance of fine grain Ti-6Al-4V alloy at very high initial strain rates, from 10–30
times faster than usual, with step reductions at prescribed levels of strain that still enables a total strain of over 2.1
(800%) to be achieved without degradation of the material. The paper also shows that the forming time to 100% deformation
can be reduced from 55 min to 9 min. This technique can be used by industry to enable faster flow times and lower production
costs of SPF parts.
This article was presented at the AeroMat Conference, International Symposium on Superplasticity and Superplastic Forming
(SPF) held in Seattle, WA, June 6–9, 2005. 相似文献
6.
Larry D. Hefti 《Journal of Materials Engineering and Performance》2008,17(2):178-182
The Superplastically Formed and Diffusion Bonded (SPF/DB) titanium structure in production today for Boeing products, not
including engines, are all diffusion bonded using matched metal tooling and are all fabricated using the common 6Al-4V alloy.
The matched metal tooling concept presents a challenge in obtaining high-quality bonds over large areas due to tolerance build-up
in the tools and the titanium sheets. Boeing Commercial Airplanes (BCA) is currently advancing the state of the SPF/DB process
in several ways. One of these advances is using stop-off between the sheets and diffusion bonding the pack first and then
superplastically forming the stiffening features. This generates a component that is very well bonded in the required locations.
However, this process also has its challenges. One of these involves how to apply the stop-off material in the proper location
using the most cost effective process. Historically, silk screening has been used to define the required pattern for the stop-off
material. This process requires several pieces of equipment including a wash booth since the screen needs to be cleaned after
each part. A paper maskant and laser scribing process has been developed for defining the stop-off pattern. Also, because
diffusion bonding is performed first, when the component is superplastically formed, there is a tendency to form creases on
the surface of the part. Methods have been developed to eliminate these surface creases on the unformed surface. Another advance
in the SPF/DB process is in the titanium alloys being used for products. A fine grain 6Al-4V material has been developed that
bonds and forms at 775 °C. The use of this material will minimize wear on the tools and presses as well as significantly reducing
the amount of alpha case on the part surface.
This article was presented at the AeroMat Conference, International Symposium on Superplasticity and Superplastic Forming
(SPF) held in Baltimore, MD, June 25-28, 2007. 相似文献
7.
Peter N. Comley 《Journal of Materials Engineering and Performance》2008,17(2):183-186
The determination of the superplastic properties of a material, just like any mechanical property, is highly dependent on
the test method, coupon geometry, and analysis of the raw data from the test. Thus the published properties of a material
from one source will differ from that of another source unless a common test method is employed. The ASTM E2448 Standard Test
Method for Determining the Superplastic Properties of Metallic Sheet Materials has been written to provide a common platform
for testing, evaluating, and publishing superplastic properties to a uniform format, useful for both academia and industry.
The Boeing Company is now using ASTM 2448 to quantify the superplastic properties of fine grain Ti-6Al-4V alloy, and is specifying
it to qualify production material to the Boeing Material Standard BMS7-385. The standard includes specimen geometry and testing
conditions, the test machine requirements, and how to analyze the data, including the basic stress vs. strain curve and determination
of ‘m’ value.
This article was presented at the AeroMat Conference, International Symposium on Superplasticity and Superplastic Forming
(SPF) held in Baltimore, MD, June 25-28, 2007. 相似文献
8.
Krajewski Paul E. Morales Arianna T. 《Journal of Materials Engineering and Performance》2004,13(6):700-709
Quick plastic forming (QPF) was developed as a high-volume, hot blow forming process for automobile components, enabling larger
volume applications than traditional superplastic forming (SPF). One critical aspect of the process is the tribological interaction
between the forming tool and the aluminum blank, as this impacts formability, surface quality, and tool durability. While
QPF has been successfully implemented for automobile components, many opportunities exist for improving the tribological condition
during the process, including the die coating or treatment, the lubricant, and the fundamental understanding of aluminum/iron
adhesion under QPF conditions (450 °C). This work reviews key tribological issues affecting QPF and identifies areas where
additional research is required.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
9.
Daniel G. Sanders Mamidala Ramulu 《Journal of Materials Engineering and Performance》2004,13(6):744-752
Superplastic forming (SPF) combined with diffusion bonding (DB) has been used successfully for the fabrication of titanium
aerospace hardware. Many of these applications have been for military aircraft, whereby a complex built-up structure has been
replaced with monolithic parts. Several methods for applying the two- and four-sheet titanium SPF/DB processes have been devised,
including the welding of sheets prior to forming and the use of silk-screened stop-off (yttria) to prevent bonding where it
is undesirable. Very little progress has been made in the past few years toward understanding and modeling the SPF/DB process
using constitutive equations and data by laboratory testing. Concerns that engineers face in designing for fatigue life, acceptable
design loads, and damage tolerance are currently being studied, but the database is very limited. This is a summary of past
work found in the literature and forms the foundation for additional research.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
10.
F. Pitt M. Ramulu P. Labossiere S. Young 《Journal of Materials Engineering and Performance》2004,13(6):735-743
Ductility of three titanium alloys was evaluated after exposure to time and temperature conditions representative of superplastic
forming (SPF). Following exposure, flexural specimens were postprocessed to remove the α-case by one of three methods: no
material removed, the standard amount of material removed by chemical processing, or a reduced amount of material removed
also by chemical processing. Results include the evaluation of the specimens per ASTM E 290-97a and AMS-T 9046, springback
analysis, and prediction of minimum bend radius criteria for the three alloys from finite element method simulation. It was
found that results varied based on alloy and exposure temperature and the reduced postprocessing of titanium SPF parts produced
acceptable results under certain conditions.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
11.
The outboard light housing on the Boeing 737 next generation aircraft was initially designed and manufactured as a cast aluminum
part. Delays in delivery and other quality problems resulted in the part being redesigned as an aluminum superplastically
formed (SPF) part. Advances in material use and tooling were necessary to successfully transition the part to the SPF form.
The resulting part is lower in cost and lighter in weight than the original. This work summarizes the steps taken to implement
the SPF outboard light housing.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
12.
利用电磁成形实验研究氢含量对Ti-6Al-4V合金室温高速压缩性能的影响,通过微观组织观察揭示氢致压缩性能机理。结果表明,氢对Ti6Al4V合金的高速压缩性能存在有益的影响。在电磁成形实验放电能量相同的条件下,Ti-6Al-4V合金的变形率随氢含量的增加呈先增加后降低的趋势。当Ti-6Al-4V合金置氢0.2%(质量分数)时,合金的变形率增加了47.0%。确定了有利于Ti6Al4V合金室温电磁成形时的最佳氢含量。分析了氢致压缩性能的机理。 相似文献
13.
M. Vanderhasten L. Rabet B. Verlinden 《Journal of Materials Engineering and Performance》2007,16(2):208-212
A superplastic Ti-6Al-4V grade has been deformed at a strain rate of 5 × 10−4 s−1 and at temperatures up to 1050 °C. Structural mechanisms like grain boundary sliding, dynamic recrystallization, and dynamic
grain growth, occurring during deformation, have been investigated and mechanical properties such as flow stress, strain hardening,
and strain at rupture have been determined. Dynamic recrystallization (DRX) brings on a decrease in the grain size. This could
be of great interest because a smaller grain size allows a decrease in temperature for superplastic forming. For DRX, the
driving force present in the deformed microstructure must be high enough. This means the temperature must be sufficiently
low to ensure storing of enough dislocation energy but must also be high enough to provide the activation energy needed for
DRX and to allow superplastic deformation. The best compromise for the temperature was found to be situated at about 800 °C;
this is quite a bit lower than the 925 °C referenced in the literature as the optimum for the superplastic deformation. At
this medium temperature the engineering strain that could be reached exceeds 400%, a value high enough to ensure the industrial
production of complex parts by the way of the superplastic forming. Microstructural, EBSD, and mechanical investigations were
used to describe the observed mechanisms, some of which are concurrent.
This article was presented at the AeroMat Conference, International Symposium on Superplasticity and Superplastic Forming
(SPF) held in Seattle, WA, June 6-9, 2005. 相似文献
14.
应力松弛是钛合金在升高温度和加载条件下的一个显著特性,也是热校形和热处理的理论基础。因此研究了一种Ti-6Al-4V钛板在923~1023 K温度范围内、几种应变水平下的拉伸应力松弛行为。结果表明,应力松弛速率随着温度的升高而增加,材料中的残余应力经过一段时间之后趋向应力松弛极限;另外,在相同温度下,不同应力水平的应力松弛极限相同。进而,建立了一种描述应力松弛行为的显式三次延迟函数,本构精度高达97%,可用于工艺设计及理论分析。最后,基于应力松弛和蠕变的关系,提出了一种隐式蠕变型本构方程描述应力松弛行为,并将识别的材料参数输入ABAQUS,数值模拟了Ti-6Al-4V的热应力松弛行为,发现模拟的应力变化规律符合应力松弛曲线,证明了蠕变型本构方程对应力松弛模拟的适用性。 相似文献
15.
Advances in fabricating superplastically formed and diffusion bonded components for aerospace structures 总被引:1,自引:0,他引:1
Larry D. Hefti 《Journal of Materials Engineering and Performance》2004,13(6):678-682
Superplastic forming and diffusion bonding (SPF/DB) production hardware is being fabricated today for aerospace applications.
Metal tooling is being used to bring the titanium sheets into contact so diffusion bonding can occur. However, due to material
sheet and tooling tolerances, good bond quality is difficult to achieve over large areas. A better method for achieving DB
is to use “stop-off” inside sealed sheets of titanium, which constitutes a pack, and then the pack is bonded using external
gas pressure. A good method for heating the pack for this process is to use induction heating. Components using “stop-off”
that were diffusion bonded first and then superplastically formed have shown much better bond quality than components that
were produced using matched metal tooling. This type of tooling has been successful at bonding small areas as long as the
exerted pressure is concentrated on the area where bonding is required. Finite element modeling is providing weight effect
solutions for titanium SPF/DB aerospace structures.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
16.
采用光学显微镜、透射电镜和拉伸试验等手段,研究了多道次两向轧制和单向轧制对不同原始状态(热轧态、水淬态和空冷态)Ti-6Al-4V合金显微组织和力学性能的影响。结果表明,热轧态Ti-6Al-4V合金的组织为片状α相+β相+少量等轴α相,水淬态Ti-6Al-4V合金形成了针状马氏体组织,空冷态Ti-6Al-4V合金形成了网状组织。Ti-6Al-4V合金适宜的两向轧制温度为700 ℃,此时合金中可见颗粒状β相弥散分布在α基体上。两向轧制Ti-6Al-4V合金的抗拉强度和屈服强度从高至低顺序为:水淬态>热轧态>空冷态,且轧向强度要高于横向;相较于单向轧制,两向轧制明显降低了Ti-6Al-4V合金板材拉伸性能的各向异性,且水淬态Ti-6Al-4V合金的轧向和横向强度差异最小,700 ℃轧制Ti-6Al-4V合金的主要细化机制为位错细化。 相似文献
17.
The thermomechanical coupling simulation of the isothermal equal channel angular pressing(ECAP) of Ti-6Al-4V alloy was conducted.The effect of processing parameters,ECAP pass number and the residual billet on the effective strain,stress and temperature distribution was investigated.Based on the coupling simulation results,it is found that the shear factor,ram speed,deformation temperature,channel intersection angle and residual billet significantly affect the ECAP deformation behaviors.Meanwhile,the experimental study of the isothermal ECAP process of Ti-6Al-4V alloy using route C,in which the repeated rotation angle around the longitudinal billet axis before reinsertion in the die was 180°,were conducted at a deformation temperature of 750°C,a ram speed of 0.3 mm·s-1,an outer arc of curvature of 60° and a channel intersection angle of 120°.Furthermore,a large amount of recrystallization occurs and some prior α phase grains grow in the post-ECAP process of Ti-6Al-4V alloy.The yield strength of post-ECAP Ti-6Al-4V alloy increases compared with that of as-received Ti-6Al-4V alloy. 相似文献
18.
The use of β titanium alloys in the aerospace industry 总被引:2,自引:0,他引:2
Beta titanium alloys have been available since the 1950s (Ti-13V-11Cr-3Mo or B120VCA), but significant applications of these
alloys, beyond the SR-71 Blackbird, have been slow in coming. The next significant usage of a β alloy did not occur until
the mid-1980s on the B-1B bomber. This aircraft used Ti-15V-3Cr-3Al-3Sn sheet due to its capability for strip rolling, improved
formability, and higher strength than Ti-6Al-4V. The next major usage was on a commercial aircraft, the Boeing 777, which
made extensive use of Ti-10V-2Fe-3Al high-strength forgings. Ti-15V-3Cr-3Al-3Sn environmental control system ducting, castings,
and springs were also used, along with Ti-3Al-8V-6Cr-4Mo-4Zr (β-C) springs. Beta-21S was also introduced for high-temperature
usage. More recent work at Boeing has focused on the development of Ti-5Al-5Mo-5V-3Cr, a high-strength alloy that can be used
at higher strength than Ti-10V-2Fe-3Al and is much more robust; it has a much wider, or friendlier, processing window. This,
along with additional studies at Boeing, and from within the aerospace industry in general will be discussed in detail, summarizing
applications and the rationale for the selection of this alloy system for aerospace applications.
This paper was presented at the Beta Titanium Alloys of the 00’s Symposium sponsored by the Titanium Committee of TMS, held
during the 2005 TMS Annual Meeting & Exhibition, February 13–16, 2005 in San Francisco, CA. 相似文献
19.
研究了SPF/DB Ti-6Al-4V合金及其激光焊接接头静态拉伸性能和疲劳性能,并获得S-N曲线.通过观察组织特征和疲劳断口形貌,分析了激光焊接对SPF/DB Ti-6Al-4V合金疲劳性能的影响.结果表明,SPF/DB T-6Al-4V合金激光焊接接头的抗拉强度略低于母材抗拉强度,而疲劳强度明显低于母材疲劳强度,约为其抗拉强度的40%.SPF/DB Ti-6Al-4V合金组织为α+β等轴细晶组织,其焊接接头组织为含α,针状马氏体α'和少量β相的魏氏组织结构.焊接接头组织结构的不均匀性,以及组织的粗大化是导致激光焊接接头疲劳性能下降的重要原因.SPF/DB Ti-6Al-4V合金疲劳断裂为塑性断裂,其焊接接头疲劳断裂为准解理断裂,这显著降低激光焊接接头的疲劳性能.而焊接气孔等焊缝表层微小几何不连续缺陷的存在往往成为激光焊接接头疲劳断裂的裂纹源. 相似文献
20.
Xu Hengqiu Li Mingzhe Zhang Rui Wang Dali Hou Fengyan Li Linlin Fan Guisen Shen Yujing Jilin University Changchun China Changchun Institute of Equipment Technology Changchun 《稀有金属材料与工程》2011,(Z3):78-81
In this paper, the process of thermal conventional spinning of Ti-6Al-4V alloy complex shape shell is studied by experiment. Billet for Ti-6Al-4V alloy board is headed in the spinning process for multi-pass conventional spinning forming. With two spinning mandrel, the first is conventional spinning pre-forming and the second is conventional end forming, vacuum heat treatment after each spinning forming. As results, the mandrel preheating temperature impacts the spinning and the appropriate temperature range plays an important role in the process of spinning. With supplemental heating means and infrared thermometer measurement ensure a stable temperature. Multi-passing thermal spinning Ti-6Al-4V alloy thins the billet thickness, using the feature obtaining the wanting complex shape shell of thick bottom and thin mouth. The spinning track, the number of spinning pass, feed rate affect the billet thinning. During thermal spinning process Ti-6Al-4V alloy rebound severe. The size reduction and feed have impact on the rebound. By modifying the spinning parameters and the mandrel repair to ensure the dimensional accuracy of workpiece. Spinning workpiece has fine grain and high strength. 相似文献