Titanium Alloys at Elevated Temperature - Structural Development and Service Behavior

298 Pages·2001·30.77 MB·English

by  Winstone

TITANIUM ALLOYS AT ELEVATED
TEMPERATURE: STRUCTURAL
DEVELOPMENT AND SERVICE
BEHAVIOUR
Edited by
M. R. Winstone
MICROSTRUCTURE OF mGH
TEMPERATURE MATERIALS
Number 4
Series Editor
A. Strang
Book 0755
First published in 2001 by
10M Communications Ltd
1 Carlton House Terrace
London SW1Y 5DB
10M Communications Ltd 2001
(Some individual papers Crown Copyright)
All rights reserved
10M Communications Ltd
is a wholly-owned Subsidiary of
The Institute of Materials
ISBN 1-86125-140-8
Typeset and printed in the UK by
Keyset Composition, Colchester
Printed and bound in the UK at
The University Press, Cambridge
Preface
The commercial exploitation of titanium alloys has a short history, still less
than 50years. This period has seen a substantial expansion of titanium usage,
in terms of quantity and diversity of application. Although once considered to
be an exotic and expensive material, titanium is now used in many sectors of
industry and prospects for further market penetration are good. The successful
processing of titanium alloys into high performance components. that operate
at elevated temperature, high stress and in aggressive environments requires a
detailed understanding of the microstructure of titanium.
The High Temperature Materials Performance Committee of the Institute of
Materials has organised a series of conferences that concentrate on micro-
structural aspects of materials. This volume contains the papers presented
during a two-day conference focused on the evolution of the microstructure
in titanium alloys; the development of the optimum structure during
processing and the subsequent effects of elevated temperature service.
The papers include invited keynotes highlighting the benefits and
challenges of using titanium alloys in various market sectors, alongside
submitted technical papers that concentrated on microstructural evolution,
thermomechanical processing, advanced fabrication, process modelling, and
structural control in Ti intermetallics. The papers provide an insight into the
status of titanium metallurgy across the world since the conference was
attended by delegates from nine countries.
Iam indebted to the Organising Committee Members for their tireless efforts
in generating a programme of high technical quality, refereeing the papers
and creating an excellent environment for stimulating discussions.
Mike Winstone
Chairman, Organising Committee
Committee Members:
Prof. W. J. Evans Dr A. Partridge
Prof. H. M. Flower Dr D. Rugg
Prof. I. P.Jones Dr R.Thomas
Prof. J. R. Nicholls
ix
Contents
Preface vi
SeriesEditor's Preface vii
Keynote Papers
Market Development - TheImplications for Research and Development 1
R. Thomas
Titanium Alloys in High Performance Automotive Engine Applications 9
M. Cope
Modelling Structural Development in the Manufacture of
Titanium Alloys 17
J. W. Brooks
Forging
Microstructural Characterisation and Modelling of Ti6Al4VAlloy
During Thermomechanical Processing in the bPhase Field 29
R. Ding, Z. X. Guo, W. Sha and A. Wilson
The Useof High Temperature X-Ray Diffractometry to Study Phase
Transformations in Ti-6AI-4V 41
R. Pederson, o. Babushkin, R. Warren and F. Skystedt
Influence of Strain Parameters on the Deformation Resistance
of Ti-6AI-4V Titanium Alloy at 1173-12 73K 51
K. Kubiak, W. Ziaja, M. Motyka and J. Sieniawski
Mechanical Properties of Closeddie Forgings of Ti-6AI-2Mo-2Cr
as a Function of Heat Treatment Parameters 59
K. Kubiak, W. Ziaja and M. Motyka
Differential Scanning Calorometry Study and Computer Modelling
of {3==? {3 Transformation in Ti-6AI-2Sn-4Zr-2Mo Alloy 69
S. Malinov, Z. Guo, W. Sha, Z. X. Guo and A. F. Wilson
Thermomechanical Processing of Tialloys: the application of a Novel
Technique to Examine Sub-{3Transus Isothermal Forging of
Ti-6AI-2Sn-4Zr-6Mo 89
M.Jackson, R.J. Dashwood, L.Christodoulou, H. M. Flower
v
vi CONTENTS
Non-Burning Alloys
Effect oj Pre-Heat-Treatment on Microstructure and Mechanical
Properties of Ti-25V-15Cr-2AI (wt%) Alloy 103
Y. G. Li,M. H. Loretto, D. Rugg and W. Voice
Effect ojX (Fe, Cr, Co, etc.) on the Morphology and Formation
of TiCin TiAlloys with Carbon Additions 113
Z. Q. Chen, Y. G. Liand M. H. Loretto
Oxidation Behaviour oj a New High Temperature Titanium
Alloy - Ti40 Bum Resistant Titanium Alloy 123
Y. Q. Zhao, L. Zhou, H. L.Qu, K. Y. Zhu and H.Wu
Fabrications
Welding of Ti-l OV-2Fe-3AI: a Comparison oj Techniques 133
I. C. Wallis and A. Wisbey
Residual Stresses,Texture and Microstructure in Electron
Beam Welds oj1M! 834 151
J.-R. Cho, S. M. Roberts, R. C. Reed and K. T. Conlon
TheMicrostructure and Superplastic Properties ojMechanically
Milled Ti-6AI-4V+ 0.5% Boron 165
T. M. Godfrey, A. Wisbey, A. Brown, R. Brydson and C. Hammond
Elevated Temperature Fatigue Crack Growth and Time Dependent
Behaviour in Ti-6246 177
J. P. Jones, M. R. Bache, W. J. Evans and S. Williams
Surface Engineering
Surface Engineering oj TiAlloysfor High Temperature Applications 187
J. R. Nicholls, M.J. Deakin and T. Rose
Surface and Substrate Stability oj Titanium Alloys Usedin Aerospace 219
C. D. Jones
Modification oj the Microstructure and Properties of Ti-1AI-1Mn
Titanium Alloy Due toNitriding and Oxynitriding under
GlowDischarge Conditions 229
J. R. Sobiecki, T. Wierzchon, T. Karpinski, J. Rudnicki
CONTENTS vii
Aluminides
Practical Advice on the Use oj Ti-45A~2-2-XD Gamma Titanium
Aluminide 237
w. Voice
Hot Plastic Flow and Workability oJ'Y-TiAI Based Alloys 251
Y. Y. Cui, R. Yang and Z. X. Guo
Effect of Grain Refinement on Continuous Cooling Phase
Traniformations in Some TiAl-Based Alloys 263
D.Hu
Deterioration of Mechanical Properties Caused by Omega Phase
in Major Alloyed TiAI-Based Alloys 277
Z. W. Huang, P. Bowen and W. Voice
Prediction ofw Phase Formation in Ti-A~X Alloys 291
G. Shao and P. Tsakiropoulos
Thermal Processing oj an Orthorhombic (Ti2A1Nb) Based Alloy 301
P. M. Sarosi, A. Partridge and I. P. Jones
Author Index 311
Subject Index 315
Titanium Market Developments:
The Implications for Research and
Development
ROGER THOMAS
Timet UKLtd, PO Box 704, Witton, Birmingham B6 7UR,UK
ABSTRACT
Research and development activity on titanium alloys is, as for many other
materials, stimulated and driven by the actual and potential uses for the material.
Applications provide the context for development work, and often provide
justification for funding of projects. In doing so, they also help us to formulate
and prioritise the questions that stimulate pure research. The enticing com-
bination of properties which titanium offers has justified the expenditure of
very substantial resources on titanium research over the last 60 years. This
presentation is an attempt to update the commercial context for titanium
research.
BACKGROUND
Ranked by natural occurrence, titanium is a very common element, but the
titanium industry remains small compared with the other metal producing
industries (see Fig. 1). This is mainly because the reactive nature of titanium
requires an extraction process, which iscapital intensive and energy intensive,
requires vacuum melting of discrete ingots and requires hot working opera-
tions to be followed by removal of oxidised surfaces. Also, the very scale of
the industries producing competing materials gives economics of scale of
production, and of scale of development effort which makes substitutions
with titanium difficult.
Figure 2 summarises the history of the titanium industry (excluding the
former Soviet Union). In the early decades of the industry, the need for
improved performance of military jet engines drove research and develop-
ment, and the strategic significance of the metal in the Cold War led
governments to encourage industrial production. The study of high
temperature deformation of titanium and its alloys, both during industrial
production, and during service, was a key theme in the development of the
jet engine. As understanding of creep, fatigue and their interactions grew,
alloys with increasing service temperature capability could be developed,
and applied at higher temperatures in the compressor sections of jet engines
1
2 TITANIUM ALLOYS AT ELEVATED TEMPERATURE
1.
]
1 5
38 1
Titanium 25 1.0
Thesteet tnd: oroaucea annualtitanium tonneae in about2.5hours!
tle<?1P11
Fig. 1 Metal industry comparison.
History and Forecast
70
60
50
40
30
20
10
0
50 55 60 65 70 75 80 85 90 95 2000
EIMlttaryAero C Commercial Aero m Core Industrial IIIEmerging Industries C Net Exp limp Ilrw Adj
Fig. 2 Titanium wrought product shipments.
3
TITANIUM MARKETDEVELOPMENTS: THE IMPLICATIONS FOR RESEARCHAND DEVELOPMENT
and for the technology to be transferred to civilaircraft engines. In the United
Kingdom, this process resulted in the progressive production of a series of
alloys with increasing maximum service temperatures (Fig. 3). Analogous
developments were made in other titanium producing countries.
CURRENTAPPLICATIONS
Control of high temperature deformation in alpha-beta and near alpha alloys
allowed titanium alloys to be used for increasing proportions of the weight of
jet engines (Fig. 4), so that modern engines typically consist of 30-350/0
titanium. This proportion seems to have reached a plateau in the last decade.
Titanium alloy developments such as cast titanium aluminide components,
or burn-resistant alloys may give further opportunities to improve engine
performance. On the other hand the pressures to build engines to a cost
limit; the properties of 'new' competing materials such as aluminium
composites, and the need to improve fuel efficiency by increasing the
temperature in the compressor may lead to other materials to be substituted
for titanium.
In parallel with the development of titanium alloys in aircraft engines, an
increasing amount of titanium alloys has been used in airframes and alloys
with appropriate properties for the applications have been developed. In
addition to the 'workhorse' 6% aluminium, 40/0 vanadium alloy, the cold
workable 3% aluminium, 2~% vanadium is used for hydraulic tubing; the
~ 500+-------------------------
g
:c
-t-----
[ 400
ro
(,j
Q.I
5 300
~
Q.I
~ 200
Q.I
t-
100
o
1954 1958 1959 1968 1977 1984
Year of Introduction
Fig. 3 History of UK alloy development.
4
TITANIUM ALLOYS AT ELEVATED TEMPERATURE
i
•
I
!
.B,.
Year
Fig. 4 Titanium content of the aeroengine.
high strength beta alloys Ti-21S and Ti-15-3 are cold formed into sheet metal
fabrications; and alloys such as Ti-O-2-3 are used for high strength, thick
section forgings. In all these cases, a thorough understanding of
deformation, microstructural evaluation, and component properties is
essential for economic production and reliable components.
MARKETOPPORTUNITIESAND METALLURGICALISSUES
As Fig. 2 indicates, applications for titanium outside the aircraft industry,
primarily based on the corrosion resistance of the metal, started to emerge
early inthe industry's history. In the last decade, gradually reducing the cost of
titanium, and the surplus global supply of the metal following the end of the
Cold War, has led to fresh initiatives to expand and diversify non-aircraft
applications of titanium.
There have been some notable successes. The Guggenheim museum in
Bilbao has provided a photogenic icon, which has stimulated many other
projects using titanium in architecture. Titanium golf heads have used an
astonishing amount of material it is claimed that in 1996, more titanium was
used in golf clubs than in military aircraft! The need for weight reduction in
land weapons systems has made titanium a necessary material, both for
structures and applique armour. Perhaps most significantly, the use oftitanium
in the automotive industry is making the transition from racing cars to