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New Processing techniques for 
Aluminum Alloys 


Frankford Arsenal 


OCTOBER 1972 

The Library ot the 

APR 23 1974 

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National Technical information Service 
U. S. DEPARTMENT OF COMMERCE 


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DOCUMENT CONTROL DATA . R & D 


ontciNATiNO ACTIVITY (Corpotmtm muthor) 

FRANKFORD ARSENAL 
Philadelphia, PA 19137 


2«. REPORT SECURITY CLASSIFICATION 

UNCLASSIFIED 


26. CROUP 


N/A 


3. REPORT TITLE 


I NEW PROCESSING TECHNIQUES FOR ALUMINUM ALLOYS 


4. DESCRIPTIVE NOT€.S (Typ» ol report end Inclusive dmtes) 

Technical research article 


B. AUTHORIS) (First naine^ middle Initial, last name) 

JEFFREY WALDMAN HAROLD hlARKUS 


HARRY SULINSKI 

e. REPORT DATE 

October 1972 

7a. TOTAL NO. OF Pi^CCS 

>J7 

76. NO. OF REFS 

15 

M. CONTRACT OR GRANT NO. 

AMCMS Code: 502E. 11.294 

6. PROJECT NO. 

DA Project: 1T062105A328 

Ce 

d. 

9a. ORIGINATOR'S REPORT NUMBERIS) 

Frankford Arsenal Report A72-5 

06. OTHER REPORT NO(S) (Any Other numbers that may be assigned 
this report) 

10. DISTRIBUTION STATEMENT 

This document has been approved for public release and sale; its distribution is 
unlimited. * 

It. SUPPLEMENTARY NOTES 

12. SPONSORING MILITARY ACTIVITY 

IS. ABSTRACT 

AMMRC 

.. ..— 


% M ^ V 

The Materials Engineering Division at Frankford Arsenal is involved in an ex¬ 
tensive research and development effort aimed at upgrading the properties of high 
strength aluminum alloys through the development of new processing techniques. 
Three areas of the work are presented. The first is concerned with solidification 
processing. Data are presented which show that, by eliminating the second phase 
particles, the mechanical properties of high strength aluminum alloys are iiq)roved, 
especially in the short transverse direction. The second area involves the develop¬ 
ment of new techniques for processing aluminum alloy ingots so that the resulting 
wrought products have a much finer grain size than that of conventionally processed 
material. Results are given vdiich show that the specially processed fine grain 
material has better ductility and toughness than conventionally processed material 
at equivalent strength levels. The final area deals with thermal mechanical pro¬ 
cessing of wrought products. A new thermal mechanical treatment is described which 
enables one to produce aluminum alloys having a better combination of strength and 
ductility than is possible with conventional processing. 


Reproduced by . 

NATIONAL TECHNICAL 
INFORMATION SERVICE 

U S Department of Commerce 
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! Aluminum Alloys 

^ Solidification 

1 Homogenization 

1 Ingot Processing 

1 Recrystallization 

?. Thermal Mechanical Treatments 

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The findings in this report are not to be construed 
as an official Department of the Army position unless 
so designated by other authorized documents* 


Digitized by the Internet Archive 
in 2018 with funding from 

University of Illinois Urbana-Champaign Alternates 


https://archive.org/details/newprocessingtecOOwald 


New Processing Techniques for Aluminum Alloys 


/■ 


J. Waldman, H. Sulinski, and H. Markus 

Pitman-Dunn Laboratory 
Frankford Arsenal 
Philadelphia, Pa. 19137 

ABSTRACT 

Tne Materials Engineering Division at Frankford Arsenal is involved 
in an extensive research and development effort aimed at upgrading the 
properties of high strength aluminum alloys through the development of 
new processing techniques. Three areas of the work are presented. The 
first is concerned with solidification processing. Data are presented 
which show that oy eliminating the second phase particles, the mechanical 
properties of high strength aluminum alloys are improved, especially in 
the short transverse direction. The second area involves the development 
of new techniques for processing aluminum alloy ingots so that the 
resulting wrought products nave a much finer grain size than that of con¬ 
ventionally processed material. Results are given which show that the 
specially processed fine grain material has better ductility and toughness 
than conventionally processed material at equivalent strength levels. The 
final area deals with thermal mechanical processing af wrought products. 

A new thermal mechanical treatment is described which enables one to 
produce aluminum alloys having a better combination of strength and due-' 
tillty than is possible with conventional processing. 


I 


INTRODUCTION 


Although high strength aluminum alloys are used in Army materiel 
because of their light weight, ease of fabrication and good mechanical 
properties, their utilization in Army components could be substantially 
increased if high strength aluminum alloys having improved ductility and 
good secondary properties could be developed. This is especially true 
in thick sections. Over the past years Frankford Arsenal has been con¬ 
ducting studies aimed at improving the strength and secondary properties 
of the 7000 series alloys through the use of improved processing tech- 
niques. This paper describes recent significant accomplishments in three 
areas of processing research on high strength aluminum alloys: 

(1) solidification and homogenization, (2) ingot processing and 
(3) thermal mechanical treatments. , , 

SOLIDIFICATION AND HOMOGENIZATION 
The strength and ductility of commercial high strength wrought 
aluminum alloys are impaired by the presence of undissolved phases in 
the microstructure. These phases arise from two sources: insoluble 
impurity phases and soluble phases that were not dissolved due to 

12 3 

inadequate homogenization treatments. Studies at Frankford Arsenal * * 

/ C £ 

and under contract with Professor M. C. Flemings of M.I.T. * * have 
shown that eliminating the undissolved phases through control of purity, 
ingot solidification rates and homogenization treatments has led to 
alloys with improved properties. 

The work was carried out on the 7000 series aluminum alloys, 
primarily 7075 (Al™5.6% Zn-2.5% Mg-1.6% Cu),^ but the results are 


2 


applicable to the 2000 and 6000 series alloys as well. It was found 

that the amount of undissolved phases in the microstructure could be 

significantly reduced by (1) low impurity content (2) small dendrite 

arm spacing (DAS) in the ingot (3) proper homogenization time and 

temperature and (4) mechanical working of the ingot. 

Studies showed that the insoluble impurity phases are mainly iron- 

rich due to the extremely limited solubility of iron in aluminum.^ 

2 

Thus, in the research, iron was limited to 0.01%. Silicon was also 

limited to less than 0.01% as a precautionary measure since it also has 

2 

low solubility in aluminum. The specifications for commercial 7075 
permit up to 0.5% max. iron and 0.4% max. silicon.^ 

The DAS is an important parameter affecting the kinetics of 
dissolution of the undissolved soluble phases because it is a measure 
of the diffusion distance atid hence, the time involved in the homogeni¬ 
zation process.^ The finer the DAS the shorter the time required for 
dissolution of the material. It was found that if the DAS is greater 
than 100 microns, complete dissolution of the soluble phases will not 
be achieved in reasonable times. By maintaining proper control of the 
casting procedures to achieve rapid local solidification rates, i.e. by 
using direct chill casting techniques, a very small DAS can be produced 
even in large ingots. 

To achieve a structure that is completely free of undissolved 
soluble phases, the homogenization temperature must be chosen so that the 
composition of the alloy is in the aluminum-rich solid solution phase 
field. In the experiments on 7075, a homogenizing temperature of 900°F 


3 


produced a completely homogeneous material, i.e. a material free of 
undissolved soluble phases.^ 

Mechanical working of the ingot at an elevated temperature prior to 
or as part of the homogenization treatment was found to decrease the 

4 

time required for complete homogenization. In fact, the greater the 
mechanical work, the less the time required for homogenization because 
the working decreases the diffusion distance between the second phase 
particles. 

Figure 1 shows the longitudinal, transverse and short transverse 

raicrostructures of commercial and specially processed (homogeneous) 

2 

7075-T6 plate. Note the absence of the second phase in the homogenized 

material. The tensile properties of these materials for 2 in. thick 

2 

plate are shown in Figure 2. It can be seen that the strengths of the 
materials are about the same whereas the ductility, as measured by 
reduction in area, of the homogeneous material is much greater than that 
of its commercial counterpart. This difference is especially notable 
in the short transverse direction. The properties of the homogeneous 
material are essentially isotropic whereas there is considerable direc¬ 
tionality present in the properties of the commercial material. 

The properties of several 7075-T6 2 in. thick plate, each contain- 

3 

ing a different amount of undissolved second phase, were documented. 

The materials examined included a commercial plate and one containing 
no undissolved second phase. The completely homogeneous 7075 plate was 
treated by heating 48 hrs/860°F + 48 hrs/900°F, quenched and aged to the 
T6 temper. The other plate materials examined were homogenized for 


4 


various times at 860°F, quenched and aged to the T6 temper in order to 
vary the degree of undissolved second phase. The significant difference 
between the various 7075-T6 plate materials was the increase in reduc¬ 
tion in area with decreasing amounts of undissolved second phase. 

(Figure 3). Similar results were obtained on 0,030 in. thick 7075-T6 
sheet.^ It was also found that in 7075-T6 sheet the strength increases 
with increasing degree of homogenization because of the increase in the 
concentration of solute elements in the matrix.^ 

Secondary properties such as fracture toughness and fatigue strength 
are improved by homogenization, especially in the short transverse 

3 

direction. (Figures 4, 5 and 6). Specifically, the plane strain 
fracture toughness in the short transverse direction in 2 in. thick 
7075-T6 plate is 22,000 psi'T/in. for commercial material and 40,000 psi 
T^rT. for completely homogeneous material. The fatigue strength in the 
short transverse direction in commercial 7075-T6 is 22,000 psi and is 

3 

27,000 psi in homogeneous 7075-T6 . It is interesting to note that the 
fatigue strengths of the two materials are equal in the longitudinal 
direction; their value is 27,000 psi showing that the fatigue strength 
of homogeneous 7075-T6 appears to be isotropic. 

INGOT PROCESSING 

Work carried out by Istituto Sperimentale del Metalli Leggeri (ISML) 
(Milan, Italy) under a US/Italy Cooperative Research Program on Aluminum 

g 

Alloys showed that properties related to ductility, such as elongation, 
reduction in area and toughness are improved by the use of an intermediate 
thermal mechanical treatment (ITMT) designed to produce a wrought product 


/ 


5 


with grains that are finer than those obtained by conventional processing 

Preliminary work has also indicated that ITMT processed forged plate may 

9 

exhibit improved stress corrosion resistance. Realizing the potential 
advantages of ITMT, a program was initiated at Frankford Arsenal to 
investigate the effect of the ISML technique as well as alternate proced¬ 
ures of ingot processing on the structure and properties of wrought 
aluminum products.In this paper the initial results obtained on 
wrought high purity homogeneous 7075 sheet and plate are presented. Work 
is in progress at Frankford Arsenal on a complete documentation of the 
effect of ITMT procesiSing on the. mechanical properties and secondary 
properties of 1 and 2 in. thick plate of such 7000 series alloys as 7075, 
7075-Zr, X7007 and 7050 and such 2000 series alloys as 2024 and 2219. 

ISML-ITMT involves a new concept in ingot processing in which ingots 
in a partially homogenized condition are worked at a relatively low tem¬ 
perature, recrystallized, homogenized and then conventionally worked (hot 
rolled) into wrought products. Since optimization of the ITMT process 
has not been completed at this time, materials have been examined in the 
as-recrystallized (AR) condition (a structure containing fine equiaxed 
grains) and the as-recrystallized + hot rolled (AR+HR) condition (a struc 
ture containing fine elongated grains) to determine the effect of grain 
morphology. Examples of the structures of AR and AR+HR+T6 ISML-ITMT 7075 
sheet are shown in Figure 7.^^ 

The key feature of the ‘ISML-ITMT method is that the anti-recrystal- 
lizing element in the 7075 ihgot, Cr, is maintained in supersaturated 
solid solution in the aluminum during both the partial homogenization 


6 


treatment and the low temperature deformation step making it ineffec- 

g 

tive in preventing recrystallization into a fine grain structure. 

Following the recrystallization step, the Cr is precipitated during the 
homogenization treatment as the E phase (Al^gCr 2 Mg 2 ) to prevent grain 
growth or recrystallization during any subsequent processing of the ITMT 

g 

material. In contrast, recrystallization does not occur during con¬ 
ventional processing because in the early stages of processing the Cr is 

precipitated as the E phase along the original cast grain boundaries; 

8 10 

this leads to coarse elongated grains. (Figure 8). Work at Frankford 
Arsenal also showed that if the Cr was precipitated prior to the initial 
deformation in the ISML-ITMT process, recrystallization into fine grains 

411 ^ 10*11 

will not occur. 

Additional studies at Frankford Arsenal have indicated however that 
if the Zn, Mg and Cu are present as precipitate particles prior to the 
initial deformation it is possible to recrystallize 7075 into fine grain 
material even though the Cr is present as the E phase during the process¬ 
ing. These studies led to the development of another ITMT method, 

FA-ITMT.In this method, the Cr is precipitated out of solution by 
a long time homogenization treatment of the ingot and then the Zn, Mg, and 
Cu are precipitated out of solution by annealing the homogenized ingot 
prior to the initial deformation. The structure of FA-ITMT fine grain 
7075 sheet in the AR and AR+HR+T6 conditions are shown in Figure 

Initial work at Frankford Arsenal on ITMT plate has been limited 
to the production and evaluation of both ISML-and FA-ITMT 7075-T6 1 in. 


7 


thick plate in the as-recrystallized condition. (Figure 10 and 11).^^ 
Although there is a duplex structure in the AR ISML-ITMT 1 in. thick 
plate (Figure 10a) the overall grain structure is significantly finer 
than that of the commercial 7075-T651 1 in. thick plate (Figure 12). The 
grain size of the FA-ITMT material is also finer than that of the coramer- 
jial 7075~T651. Increasing the recrystallization temperature to 960°F 
eliminated the duplex structure and produced fine equiaxed grains in the 
ISML-ITMT plate (Figure 10).^^ 

The tensile properties of conventionally processed, ISML-ITMT and 
FA-ITMT homogeneous 7*^75-T6 sheet and plate are shown in Table 
It can be seen that the fine grained ITMT 7075-T6 has equivalent strength 
and significantly better ductility than the conventionally processed 
material. Also, Table I clearly shows the added benefits to be gained 
by utilizing ITMT with the concepts of homogenization. 

The stress corrosion tests of the ITMT and conventionally processed 
7075-T6 1 in. thick plate indicate that the fine grained ITMT material 
may have a slightly better stress corrosion resistance than the con¬ 
ventionally processed material.^^ Additional testing is being conducted 
to verify these results. 

Other work at Frankford Arsenal has shown the dependence of the ten- 

11 

sile properties on the grain size of the wrought plate. (Figure 13) 

It can be seen that there is only a slight dependence of the yield 
strength on grain size. Although this behavior is contrary to the usual 
strengthening effect of a fine grain size in pure metals and solid solu¬ 
tion alloys, a negligible grain size dependence of the yield strength 

12 

has also been reported in 2024-T4, The pronounced dependence of the 

ductility on grain size in 7075-T6 can also be seen from Figure 13. 

8 


THERMAL MECHANICAL TREATMENTS 


Thermal mechanical treatments as discussed in this section are those 
processes which combine thermal treatments and mechanical processing 
techniques to improve the properties of aluminum alloy mill products 
such as sheet and plate over those obtained in the standard T6 condi¬ 
tion. (Solution heat treated, quenched and artificially aged). A 
common thermal mechanical treatment is the T8 temper which involves 
solution treating, quenching, cold working and then artificially aging. 
Since the cold work is applied prior to aging, the aging kinetics are 
affected. In the 2000 and 6000 series, the cold work accelerates the 
aging kinetics and the strength is greater than that in the T6 tamper. 

The T8 temper is a commercial temper in these alloy systems. Cold work 
prior to aging does not have a favorable influence on the aging kinetics 
of 7000 series alloys and the strength in the T8 temper is no better 
than that in the T6 temper. For these reasons, T8 is not a commercially 
used temper in 7000 series alloys. The failure of the 7000 series alloys 
to respond favorably to cold work following solution'~heat treatment may 

be due to the fact that the 7000 series alloys harden In the T6 temper 

13 

almost entirely by GP zones and that cold work decreases the rate of 

14 

G.P. zone formation. 

One means of raising the strength of the 7000 series alloys is the T9 
temper. However, this temper is only a mechanical treatment which 
involves cold working the material in the T6 condition. In the T9 temper, 
the cold working does not influence the aging kinetics because the cold 


9 


work is applied after aging is essentially completed; the effects of 
aging and cold work are only additive. Cold working the T6 temper 
material does increase its strength, but the ductility of the material 
is greatly reduced. Also, since the T9 temper is not readily applied 
commercially, it is not used in the 7000 series alloys. 

Based on the above information, ISML, under the US/Italy Cooperative 

Research Program previously mentioned, developed a new thermal mechanical 

8 15 

treatment termed Final Thermal Mechanical Treatment (FTMT) * for 7000 
series alloys, which gives better combinations of strength and ductility 
than can be obtained by the use of conventional treatments. Although 
FTMT was developed primarily for the 7000 series, it has been shown to 
give similar results for the 2000 and 6000 series alloys. FTMT consists 
of the application of plastic deformation between an Initial and a final 
artificial aging step. That is, FTMT involves solution heat treatment, 
quench, natural age for 3 to 7 days , low temperature artificial age, cold 
work, and final artificial age either at a higher temperature than the 
first artificial aging step or for a longer time at the same temperature 
as the first artificial aging step. For example, in the FTMT of 7075 alloy 
the first artificial aging step is carried out at about 220°F, the working 
is 10 to 30% at room temperature (although working temperatures up to 375*^^ 
are acceptable), and the final artificial aging step is carried out in the 
temperature range of 220° to 250°F.^ 

The yield strength and corresponding elongation of several 7000 
series commercial purity sheet alloys in the FTMT and T9 conditions are 


10 


It can be seen that for a given treatment, 


plotted in Figure 
T9 or FTMT, the strength increases and the elongation decreases. 

However, FTMT gives a better combination of strength and elongation 
than does the T9 temper; for a given strength, the elongation is 
greater in the FTMT than in the T9 temper and for a given elongation, 
the strength is greater in the FTMT than in the T9 temper. 

Recent work at Frankford Arsenal has involved the application of 

FTMT to homogeneous plates of 7039, 7075, X7007 and X7050.^^ As can 

1 • 

be seen from Table II the same benefits achieved in FTMT sheet are 

recognized in FTMT plate. Work on the effect of FTMT on the secondary 

properties of 7000 series alloys is in progress at Frankford Arsenal. 

It has been reported that extruded 7075 in the FTMT temper has better 

fatigue strength than extruded 7075“T6.^^ 

There has been little research on the mechanisms involved in FTMT. 

8 15 

However, on the basis of electron microscopy observations * and aging 
14 

studies it appears that the improvements achieved with FTMT are due 
to the presence of a finely distributed G.P. zone structure prior to 
deformation and the stability of the dislocation structure (produced by 
the deformation step) during the final aging step. 

Although the work at Frankford Arsenal has involved the applica¬ 
tion of FTMT to produce material with substantially higher strength than 
T6 material, other recent work used FTMT to produce 7075 that will have 

the strength of the T6 temper and the stress corrosion immunity of the 
18 

T73 temper. With regard to the engineering applications of FTMT, 
Frankford Arsenal has successfully applied FTMT to Small caliber 


11 


library 
UNtVERSnX w 


aluminum cartridge cases to obtain improved strength properties at 

19 

critical locations in the cartridge case. 

SUMMARY 

Recent work at Frankford Arsenal on upgrading the properties of 
high strength aluminum alloys through improved processing techniques is 
presented. The results show: (1) Elimination of the undissolved second 
phase by controlled solidification and homogenization techniques improves 
the mechanical properties of high strength aluminum alloys, especially in 
the short transverse direction, (2) New ingot processing techniques 
termed Intermediate Thermal Mechanical Treatments (ITMT)produce wrought 
aluminum alloy products that have a much finer grain size, significantly 
better ductility and at least equivalent stress corrosion resistance to 
conventionally processed materials at equivalent strength levels, (3) A 
new thermal mechanical treatment, Final Thermal Mechanical Treatment 
(FTMT), produces wrought high strength aluminum alloys that have a^better 
combination of strength and ductility than is possible with conventional 
treatments. 

By using controlled solidification and homogenization techniques in 
conjunction with the ITMT and FTMT processes, potential new avenues of 
approach are available for producing aluminum alloys with superior 
engineering properties. 


12 


ACKNOWLEDGEMENTS 


The authors wish to thank Messrs, D, H, Kleppinger and C. J. Porembski 
Branch Chief, and Group Leader, respectively. Materials Engineering 
Division, Pitman-Dunn Laboratory, Frankford Arsenal for many helpful 
discussions in this work. 


13 


REFERENCES 


1- Antes, H. W., Lipson, S. and Rosenthal, H., "Strength and Ductility 
of 7000 - Series Wrought-Aluminum Alloys as Affected by Ingot 
Structure," Trans. TMS-AIME vol. 239 No. 10 (1967) 1634 - 1642 

2“ Antes, H. W. and Markus, H., "Homogenization Improves the Properties 
of 7000 Series Aluminum Alloys," Met. Eng. Quart, vol. 1€ No. 4 
(1970) 9-11 

3- Mulherin, J. H. and Rosenthal, H., "Influence of Nonequilibrium 
Second-Phase Particles Formed During Solidification upon the Mech¬ 
anical Behavior of an Aluminum Alloy," Met. Trans, vol. 2 No. 2 (1971) 
427 - 432 

4- Singh, S. N. and Flemings, M. C., "Solution Kinetics of a Cast and 
Wrought High Strength Aluminum Alloy Trans TMS-AIME vol. 245 No. 8 
a968) 1803 - 1809 

5- Singh, S. N. and Flemings, M. C., "Influence of Ingot Structures and 
Processing on Mechanical Properties and Fracture of a High Strength 
Wrought Aluminum Alloy," Trans TMS-AIME vol. 245 No. 8 (1969) 1811 - 
1819 

6;^ Reti, A. M., "Thermomechanical Processing of Aluminum Alloys," Sc.D. 
thesis (1970) Massachusetts Institute of Technology, 

7- "Registration Record of Aluminum Association Alloy Designations and 
Chemical Composition Limits for Wrought Aluminum Alloys" Aluminum 
Association, New York,^N. Y. 10017 (March 1, 1972) 


14 


8- DiRusso, E., "Improvements of the Properties of High Strength Aluminum 
Alloys by Means of Complex Thermomechanical Treatments," Istituto 
Sperimentale dei Metalli Leggeri (ISML), Milan, Italy, Report No, 71/ 
21311 April 30, 1971 

9- DiRusso, E., Conserve, M. and Buratti, M."Preliminary Results of 
Mechanical Stress-Corrosion Tests on Plates of 7075 Alloy Produced 
by a New processing Technique, "AGARD Conference Proceedings No, 98, 
Paper 30 January 1972 

10- Waldman, J, and Sulinski, H, V,, "Effect of Ingot Thermal Mechanical 
Processing Treatments on the Grain Size and Properties of Wrought 7075 

'■T . 

Alloy," Presented at the Army Science Conference, West Point, N, Y, 
20-23 June 1972 

- 

11- Waldman, J,, Sulinski, H. and Markus, H., "The Effect of Ingot 
Processing Treatments on the Grain Size and Properties of 7075 Sheet 
and Plate," to be submitted to Met, Trans, 

12- Dean, W, A, and Anderson, W, A,, "Effects of Grain Size in Aluminum 
Alloys," Ultrafine - Grain Metals ed, J, J, Burke and V, Weiss, Proc, 
qf 16th Sagamore Army Materials Research Conference (Aug, 19-22, 1969) 
373-375 

13- Aluminum vol, I ed, Kent R, Van Horn, ASM, (1961) I51 

14- Ceresara, S, and Fiorini, P,, Istituto Sperimentale dei Metalli Leggeri 
(ISML) Milan, Italy Report No, 70/20088 March 9, 1970 

15- Conserva, M,, DiRusso, E, and Gatto, F,, "A New Thermomechanical Treat¬ 
ment for Al-Zn-Mg Type Alloys," Alumlntb, e Nuovo Metallurgi^ No, 9 
(1968) 441-445 


15 


16- Ruch, L. and Sulinski, H., "Final Thermal Mechanical Treatment of 7039, 
7075, X7007 and X7050 Alloys" Frankford Arsenal Report (in preparation) 

17- Ostermann, F., "Improved Fatigue Resistance of Al-Zn-Mg-Cu (7075) 

Alloys Through Thermomechanical Processing," Met. Trans, vol, 2 
No. 10 (1971) 2897 - 2902 

18- Sommer, A. W., Paton, N. E. and Folgner, D. G., "Effects of Thermo¬ 
mechanical Treatments on Aluminum Alloys, "Los Angeles Division of 
North American Rockwell Corporation, Los Angeles, Calif., Air Force 
Materials Laboratory Contract Report. AFML-TR-72-5 (Feb. 1972) 

19- George, H. P., "Metallurgical Advances for Aluminum Cartridge Case 
Application," Frankford Arsenal Report (in preparation) 


16 


TABLE I - Long Transverse Tensile Properties of Homogeneous ITMT 
7075--T6 Sheet (0.160 in. thick) and Plate tl in. thick) 
(ref. 10, 11) 



Yield Strength 

Ultimate 

Tensile 

Elonga- 

Reduc¬ 
tion in 


(0.2% offset) 

Strength 

tion 

Area 

Material 

ksi 

ksi 

% 

% 


Sheet 


Conventional 

69.8 

83.3 

12.8 

31.1 

ISML-ITMT 

71.0 

84.0 

14.6 

44.5 

FA-ITMT 

71.8 

84.1 

14.9 

42.6 

Plate 

* 

Conventional 

72.8 

82.5 

9.5 

15.0 

Conventional 

75.8 

86.0 

12.5 

20.5 

ISML-ITMT 

73.7 

83.2 

18.2 

29.6 

FA-ITMT 

73.9 

83.0 

19.0 

35.1 


* Commercial Purity 


17 









TABLE II - Longitudinal Tensile Properties of Homogeneous 7039, 7075, 


X7007 

and X7050 Plate in 

the T6 and ! 

FTMT Tempers 

. (ref. 



Ultimate 


Reduc- 


Yield Strength 

Tensile 

Elonga- 

tion 


(0.2% offset) 

Strength 

tion in 

in Area 

Material 

ksi 

ksi 

2 in. % 

% 

7039-T6 

49.1 

60.2 

12.7 

35.2 

7039-FTMT 

69.4 

76.6 

9.2 

17.2 

7075~T6 

78.7 

87.0 

11.0 

14.0 

7075-FTMT 

87.0 

92.4 

8.4 

14.0 

X7007~T6 

70.1 

74.6 

14.1 

35.5 

X7007-FTMT 

80.5 

84.0 

9.3 

15.6 

X7050-T6 

84.2 

88.9 

10.8 

30.2 

X7050-FTMT 

92.1 

97.7 

8.6 

27.6 


18 







FIGURE CAPTIONS 


Figure 1. 


Figure 2. 


Figure 3. 


Figure 4. 


Figure 5. 


Figure 6. 


Figure 7. 


Figure 8. 


Figure 9. 


Longitudinal, transverse and short transverse microstruc¬ 
tures of (a) commercial 7075-T6 and (b) specially processed 
7075-T6 plate, (ref. 2) 

Longitudinal, transverse and short transverse tensile 
properties of commercial 7075-T6 and specially processed 
7075-T6 plate, (ref. 2) 

Ductility characteristics of 7075-T6 aluminum alloy as a 
function of direction and second phase concentration, (ref. 3) 
Relationship between the plane strain fracture toughness in 
the short transverse direction and the concentration of second 
phasesoof 7075-T6 aluminum alloy, (ref. 3) 

Longitudinal fatigue characteristics of commercial and 
homogenized 7075-T6 aluminum alloy, (ref. 3) 

Short transverse fatigue characteristics of commercial and 
homogenized 7075-T6 aluminum alloy, (ref. 3) 

Microstructures of ISML-ITMT 7075 sheet, (a) as-recrystallized 
and (b) as-recrystallized + hot rolled + T6. Longitudinal 
sections. Mag. lOOX. Keller’s etch. (ref. 10, 11) 
Microstructure of conventionally processed 7075-T6 sheet. 
Longitudinal section. Mag. lOOX. Keller’s etch. (ref. 10, 11) 
Microstructures of FA-ITMT 7075 sheet, (a) as-recrystallized 
and (b) as-recrystallized + hot rolled + T6. Longitudinal 
sections. Mag. lOOX. Keller's etch. (ref. 10, 11) 


’ > 


19 


Figure 10. 


Figure 11. 


Figure 12. 


Figure 13. 


Figure 14. 


Microstructures of as-recrystallized ISML-ITMT 7075 1 in. 
thick plate. The material was recrystallized at (a) 860°F 

i 

and (b) 960°F for 24 hrs-and quenched. Longitudinal sections. 
Mag. lOOX. Keller’s etch. (ref. 11) 

Microstructure of as-recrystallized FA-ITMT 7075 1 in. thick 
plate. Longitudinal section. Mag. lOOX, Keller's etch. 

(ref. 11) 

Microstructure of commercial 7075-T651 plate (1 in. thick). 
Longitudinal section. Mag. lOOX. Keller's etch. (ref. 11) 
The mechanical properties of 7075-T6 as a function of the 
reciprocal of the square root of the grain size measured 
from a longitudinal section in a direction perpendicular to 
the rolling direction, (ref. 11) 

Yield strength and elongation of 7001, 7005, 7075 and 7139 
alloys in the T6, T9 and FTMT tempers. (ref. 8, 15) 


i 


20 



21 














E3 COMMERCIAL 

iVSn SPECIALLY 
PROCESSED 


H 

3 


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*✓) 


>- 


6 ? 

od 



Figure 2. Longitudinal, transverse and short transverse 
tensile properties of conimercial 7075-T6 and specially 
processed 7075-T6 plate. (ref. 2) 


I 


22 













































































































% ‘VBdv Ni NoiiDnaad 



r*v 


23 


Figure 3. Ductility characteristics of 7075~T6 
aluminum alloy as a function of direction and 
second phase concentration. (ref. 3) 








NlVaj-S BNVId 



24 


Figure 4. Relationship between the plane 
strain fracture toughness in the short 
transverse direction and the concentration 
of second phases of 7075-T6 aluminum alloy, 
(ref. 3) 







25 


Figure 5. Longitudinal fatigue characteristics of commercial 
and homogenized 7075-T6 aluminum alloy. (ref. 3) 




k 


26 


Figure 6. Short transverse fatigue characteristics of commercial 
and homogenized 7075-T6 aluminum alloy. (ref. 3) 




^ . N ^ t.' ^ y’'' ' ■ ( , .v-< ^ . - . ' ‘ ^ / 

. *-1-^ . - . '^r7 I> . v' •« V. . • - / . i I y ^ ^ ' 



(a) 



(b) 


Figure 7. Microstructures ofi ISML-ITMI 7075 sheet 

(a) as-recrystallized and (b) as-recrystallized^+ 

T6. Longitudinal sections. Mag. lOOX. Keller s 


hot rolled + 
etch. 


(ref. 10, 11) 


% > 


27 





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CO • 

0) X 

as 

U iH 

o. 


00 


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s 

g 

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o 

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bor>. 
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28 


Keller's etch. (ref. 10, 11) 


























































FlRure MicroBtructures of FA-ITMT 7075 sheet. . 

(a) as-recrystallized and (b) as-recrystallized + hot rolled + 
T6. Longitudinal sections. Mag. lOOX. Keller s etch. 

(ref. 10, 11) * 

29 






























(a) 860®F (b) 960®? 


Figure 10. Microstructures of as-recrystallized ISML-ITMT 7075 
1 in. thick plate. The material was recrystallized at (a) 860°F 
and (b) 960®F for 24 hrs and quenched. Longitudinal sections. 
Mag. lOOX. Keller's etch. (ref. 11) 



30 
















Figure 
1 in. 
etch. 


11. Microstructure of as-recrystallized 
thick plate. Longitudinal section. Mag. 
(ref. 11) 


FA-ITMT 7075 
lOOX. Keller’s 


31 















































Figure 12. Microstructure of commercial 7075-T651 plate (1 in. 
thick). Longitudinal section. Mag. lOOX. Keller’s etch. 

(ref. 11) 


32 









































eo 


-p- 

1 

1 

-1- 




o 



70 



o 

G 

G 



60 





- 



G 

Y.S. (0.2Z offset), ksl 




□ 

R e A • f X 



50 


A 

E In 1 ln.,Z 


- 






□ 

40 

- 




-1— 

□ 

□ 

□ 

30 





o t? 



□ □ 
□g 

□ □ 

□ 

□ 

20 



AA 

a4j^ 

A ^ ^ - 

A 

10 


1 

1 

1 


0 

0 

2 

4 

6 

8 10 


(D^^) (mra'S 


Figure 13. The mechanical properties of 7075-T6 as a 
function of the reciprocal of the square root of the 
grain size measured from a longitudinal section in a 
direction perpendicular to the rolling direction, 
(ref. 11) 


3.3 




Figure 14. Yield strength and elongation of 7001, 7005, 7075 and 
7139 alloys in the T6, T9 and FTMT tempers. (ref. 8, 15) 


34 









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UNIVERSITY OF ILLINOIS-URBANA 

669.722W14N C001 

NEW PROCESSING TECHNIQUES FOR ALUMINUM A 



8827724