Titanium Alloys: Russian Aircraft and Aerospace Applications

214 Pages·2005·21.09 MB·English

by  Valentin N. Moiseyev

Titanium Alloys
Russian Aircraft and
Aerospace Applications
Advances in Metallic Alloys
A series edited by J.N. Fridlyander, All-Russian
Institute of Aviation Materials, Moscow, Russia and
D.G. Eskin, Netherlands Institute for Metals Research,
Delft, The Netherlands
Volume 1
Liquid Metal Processing: Applications to Aluminum Alloy Production
I.G. Brodova, P.S. Popel and G.I. Eskin
Volume 2
Iron in Aluminum Alloys: Impurity and Alloying Elment
N.W. Belov, A.A. Aksenov and D.G. Eskin
Volume 3
Magnesium Alloy Containing Rare Earth Metals: Structure and Properties
L.L. Rokhlin
Volume 4
Phase Transformations of Elements Under High Pressure
E.Yu Tonkov and E.G. Ponyatovsky
Volume 5
Titanium Alloys: Russian Aircraft and Aerospace Applications
Valentin N. Moiseyev
Titanium Alloys
Russian Aircraft and
Aerospace Applications
Valentin N. Moiseyev
Boca Raton London New York Singapore
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3273_Discl.fm Page 1 Monday, June 20, 2005 7:21 AM
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Library of Congress Cataloging-in-Publication Data
Moiseyev, Valentin N.
Titanium alloys in Russia / Valentin N. Moiseyev.
p. cm. -- (Advances in metallic alloys ; v. 5)
Includes bibliographical references and index.
ISBN 0-8493-3273-7 (alk. paper)
1. Titanium alloys--Russia (Federation) I. Title. II. Series.
TN693.T5M58 2005
620.1'89322--dc22 2005041889
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00 Contents v-vi.fm Page v Wednesday, May 18, 2005 1:36 AM
Contents
Introduction 1
Chapter 1 Structure of Titanium Alloys 5
1.1 Effect of impurities on the properties of titanium 5
1.2 Interaction of titanium with other elements 9
1.3 Solid α- and β-solutions in titanium alloys 13
1.4 Chemical compounds in titanium alloys 17
1.5 Stability of solid α- and β-solutions 22
1.6 Phase transformations in titanium alloys 25
1.7 Enhancement of mechanical strength of titanium alloys 29
1.8 Enhancement of high-temperature strength of titanium alloys 35
References 42
Chapter 2 Structural Titanium Alloys 47
2.1 General characteristics 47
2.2 High-ductility low-strength alloys 51
2.3 Medium-strength alloys 67
2.4 High-strength alloys 84
References 116
Chapter 3 High-Temperature Titanium Alloys 119
3.1 General characteristics 119
3.2 Martensite-type high-temperature alloys 121
3.3 High-temperature pseudo-α-alloys 141
References 147
Chapter 4 Functional-Purpose Titanium Alloys 149
4.1 Titanium alloys operated at low temperatures 149
4.2 Special-purpose corrosion-resistant titanium alloys 150
4.3 Intermetallics-based titanium alloys 156
4.3.1 Titanium aluminides 157
4.3.2 Titanium nickelide 159
4.3.3 Eutectoid-based alloys 161
4.4 Titanium alloys for production of cast shapes 162
References 167
Chapter 5 Technological Properties of Titanium Alloys 169
5.1 Formation of the structure and properties in hot deformation
of titanium alloys 169
5.2 Heat treatment of titanium alloys 174
00 Contents v-vi.fm Page vi Wednesday, May 18, 2005 1:36 AM
vi THE RISE OF THE SUPERCONDUCTORS
5.2.1 Annealing 176
5.2.2 Hardening heat treatment (quenching and aging) 180
5.3 Welding of titanium alloys 181
5.4 Surface engineering of titanium alloys 186
5.4.1 Interaction of titanium with atmospheric gases
during heating 186
5.4.2 Effect of mechanical treatment on titanium alloy
castings 188
5.4.3 Surface hardening of titanium alloy items 189
References 191
Chapter 6 Applications of Titanium and Titanium Alloys 195
6.1 Titanium alloys in the aircraft industry 196
6.2 Titanium in engine manufacturing 199
6.3 Titanium in rocket manufacturing 201
6.4 Titanium in shipbuilding 202
6.5 Titanium in the chemical engineering industry
and other fields 202
References 205
Subject Index 207
00 Introduction 1-3l.fm Page 1 Wednesday, May 18, 2005 1:36 AM

Introduction
Titanium is a rather new metal and is, probably, the last addition to the comparatively
small group of structural materials for large-capacity constructions. Along with iron,
aluminum, magnesium, copper, and nickel, it becomes one of the essential metal
materials for modern machine building, as its reserves in the Earth’s crust are rather
big.
The advantages of titanium as a structural material are well known. The major
stimulus for titanium to be used in various engineering fields are its high specific
strength and high-temperature strength within a broad temperature range, and also a
high corrosion resistance in most aggressive media.
Titanium used in industries is usually not technical-grade titanium but its alloys,
which exceed the nonalloyed metal by mechanical strength, high-temperature
strength and other useful properties. The temperature range of the best application of
titanium alloys is from the deep-freeze temperatures (cryogenic alloys) up to
500–600°C (high-temperature alloys).
A characteristic feature of titanium and its alloys is high sensitivity to im-
purities, especially atmospheric oxygen and nitrogen. Oxygen, nitrogen and other
impurities form alloys of the type of interstitial solid solutions or metallide phases
with titanium and significantly affect the properties of metal when present even in
minor amounts (decimal and sometimes even hundredth fractions of a percent). This
explains the large number of grades of initial spongy titanium cast to produce semi-
products. Russian state standard 17303-72 establishes the following grades and
chemical compositions for initial spongy titanium (Table 1).
Comparison of titanium with other structural metals shows it to be the most
refractory and to have lower values of thermal conductivity, electrical resistance and
ooooooooooo
Table 1 Grades and chemical compositions of spongy titanium.
Grade Maximal Chemical composition, %, no more than
hardness, HB
(10/1500/30) N C Cl Fe Si Ni O
2 2
TG-90 90 0.02 0.02 0.08 0.06 0.01 0.05 0.04
TG-100 100 0.02 0.03 0.08 0.07 0.02 0.05 0.04
TG-110 110 0.02 0.03 0.08 0.09 0.03 0.03 0.05
TG-120 120 0.03 0.04 0.08 0.01 0.03 0.05 0.06
TG-130 130 0.03 0.04 0.10 0.13 0.04 0.05 0.08
TG-150 150 0.04 0.05 0.12 0.20 0.04 0.05 0.10
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2 VALENTIN N. MOISEYEV
Table 2 Physical properties of titanium and other metals.
Properties Ti Mg Al Fe Cu
Melting temperature, °C 1665 650 660 1535 1083
Density, g/cm3 4.51 1.74 2.70 7.86 8.94
Thermal conductivity, Cal/cm s deg 0.0407 0.35 0.57 0.17 0.92
Electrical resistance, µΩ cm 55.4 4.40 2.68 10.0 1.72
Heat capacity, Cal/g deg 0.126 0.245 0.211 0.109 0.093
Coefficient of thermal expansion, ×106, deg–1 8.9 25.7 24.0 11.9 16.4
Young’s modulus, kgf/mm2 11200 4500 7250 20000 12250
and thermal expansion. By density, titanium is attributed to light metals and occupies
an intermediate position between aluminum and iron (Table 2).
Similar to iron, titanium is a polymorphic metal and has a phase transformation
at a temperature of 882°C. Below this temperature, the hexagonal close-packed
lattice of α-titanium is stable; above it, the body-centered cubic lattice of β-titanium.
There is a great variety of commercial titanium alloys which differ by their
structures, physical, chemical, and mechanical properties, and applications.
All titanium alloys are divided into three groups by the type of structure: (i)
alloys based on solid α- and β-solutions, (ii) alloys based on solid solutions with some
amount of a chemical compound and (iii) alloys based on a chemical compound.
The most numerous and traditional group are titanium alloys which represent
solid solutions. As a rule, they are structural alloys with a high ratio of strength and
ductility, satisfactory fusion weldability, capability of hardening heat treatment,
good thermal stability, and other properties required for modern structural materials.
Solid-solution titanium alloys retain high strength at temperatures up to 350–450°C.
Solid-solution alloys with chemical compounds are also widespread. This is a
class of titanium alloys based on α-, (α+β), and β-solid solutions with an amount of
disperse formations of a chemical compound, which ensures a significant
enhancement of strength and high-temperature strength. Commercial titanium alloys
contain a minor amount of a chemical compound or the initial stage of its formation
in the α- or (α+β)-matrix. Aluminum (Ti Al), silicon (Ti Si ), carbon (TiC), boron
3 5 3
(TiB), etc., are used as alloying elements forming chemical compounds in titanium.
Other, more complex chemical compounds can be formed in multicomponent alloys.
Development of solid solution-based alloys with a chemical compound made it
possible to increase the operational temperatures up to 500–600°C.
Titanium alloys based on chemical compounds have been developed
comparatively recently and quickly became the focus of attention owing to their
properties, unique in some cases. There are at least three types of such materials,
which are of commercial interest. These are heat-resistant alloys based on titanium
aluminides Ti Al (α -phase), TiAl (γ-phase); shape memory alloys based on
3 2
titanium nickelides (TiNi) and fire-safe alloys based on the eutectoid (α+Ti Cu and
2
α+TiCr). The latter type can only conditionally be attributed to alloys based on a
chemical compound; however, their functional properties are determined by
eutectoid which includes the compound.
00 Introduction 1-3l.fm Page 3 Wednesday, May 18, 2005 1:36 AM
TITANIUM ALLOYS: RUSSIAN AIRCRAFT AND AEROSPACE APPLICATIONS 3
Alloys based on aluminides can be operated at temperatures up to 700–800°C.
In Russian practice, there are over 30 commercial titanium alloys that are
divided into the following groups by their preferable applications: structural alloys,
high-strength thermally hardened alloys, high-temperature alloys, alloys for fabri-
cation of cast shapes, alloys with special properties (for cryogenic temperatures, for
very aggressive media, shape memory alloys, etc.).
The monograph considers titanium alloys with respect to these groups and
applications. Along with the description of the physical and mechanical properties
of various-purpose alloys, we discuss the general regularities in the change of alloys’
structure and properties depending on their chemical composition and heat treatment.
The data in Introduction make it possible to predict the behavior of various alloys at
all stages of production, and also in operation of fabricated products at elevated
temperatures and stresses.
We present the major parameters of titanium alloys’ treatment, taking into
consideration their structural features and the requirements to their physical and
mechanical properties.
The chapter on special-purpose titanium alloys discusses (besides alloys for
cryogenic temperatures, with decreased tendency to oxidation, corrosion-resistant
and shape memory alloys) a new direction in developing and using titanium alloys
based on chemical compounds and solid solution-based alloys with intermetallic
compounds.
In conclusion, we look at the experience and efficiency of using titanium alloys
in various fields of machine building.
The monograph is intended for metallurgists, physical metallurgists, design and
process engineers, and metallurgical students.