PROCESSING AND PROPERTIES OF 2091 AND 8090 FORGINGS

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Submitted on 1 Jan 1987

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PROCESSING AND PROPERTIES OF 2091 AND 8090 FORGINGS

D. Marchive, M. Charue

To cite this version:

D. Marchive, M. Charue. PROCESSING AND PROPERTIES OF 2091 AND 8090 FORGINGS.

Journal de Physique Colloques, 1987, 48 (C3), pp.C3-43-C3-48. �10.1051/jphyscol:1987306�. �jpa- 00226529�

JOURNAL DE PHYSIQUE

Colloque C3, suppigment au n09, Tome 48, septembre 1987

PROCESSING AND PROPERTIES OF 2091 AND 8090 FORGINGS

D. MARCHIVE and M.O. CHARUE

F o r g e a l , B.P. 45, F - 6 3 5 0 2 I s s o i r e C e d e x , F r a n c e

This study was conducted t o evaluate t h e p o t e n t i a l use o f c u r r e n t l y a v a i l a b l e 2091 and 8090 a l l o y s as forging m a t e r i a l .

Three d i f f e r e n t product forms have been s t u d i e d :

-

...

-

...

-

1

-

A l a r g e m a j o r i t y o f Aerospace p r e c i s i o n d i e f o r g i n g s a r e p r e s e n t l y made u s i n g 7075 T73 a l l o y . FORGEAL1s i n i t i a l aim was t o o b t a i n a l e v e l o f guaranteed p r o p e r t i e s o f 7075 T73 f o r t h e A1-Li p r e c i s i o n d i e forgings. Such p r o p e r t i e s a r e shown on t a b l e 1.

Table 1 : P r o p e r t y t a r g e t s o f A1-Li p r e c i s i o n d i e f o r g i n g s 1.2 FORGEAL1s experience

Fig. 1 shows a s e l e c t i o n o f A1-Li p r e c i s i o n d i e f o r g i n g s produced by FORGEAL.

A1-LI a l l o y s are w e l l adapted for t h e manufacture o f p a r t s w i t h r i b s and t h i n webs t y p i c a l o f d i e forging.

Transverse d i r e c t i o n 440

370 4

- T-L

3 27 Mechanical p r o p e r t i e s

TS (MPa) YS (MPa) EL (%) F r a c t u r e thouqhness

K1C (MPafi)

Lonq d i r e c t i o n 455 385 7

- ^L-T

32 Corrosion r e s i s t a n c e E x f o l i a t i o n c o r r o s i o n

(EXCO Test) I n t e r g r a n u l a r c o r r o s i o n

(MIL H 6088 - A t t a c k depth) Stress c o r r o s i o n

(AIR 9048 - 30 days)

.

E~

=s 150 pm

Q- 2 285 MPa

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1987306

0 - 4 4 JOURNAL DE PHYSIQUE

1.3 2091 a l l o y

The study s t a r t e d w i t h 2091 a l l o y i n 1985. I t has n o t been p o s s i b l e up t o now t o ob- t a i n t h e 7075 T73 p r o p e r t i e s w i t h 2091 a l l o y p r e c i s i o n d i e f o r g i n g s .

However, w i t h such an a l l o y , i t i s p o s s i b l e t o achieve d i f f e r e n t combinations o f pro- p e r t i e s which might be o f i n t e r e s t t o t h e Aerospace i n d u s t r y .

* T6 temper (peak aged) : h i g h mechanical p r o p e r t i e s b u t low c o r r o s i o n r e s i s t a n c e .

* T7x temper : good c o r r o s i o n r e s i s t a n c e b u t medium s t r e n g t h . Table 2 shows compared p r o p e r t y l e v e l s o f T6 and T7x tempers.

Table 2 : Comparison o f T6 and T7x c o n d i t i o n s Mechanical p r o p e r t i e s

Long d i r e c t i o n

---

TS (MPa) YS (MPa)

EL (%)

Ifan~vefse-Gfec tion

TS (MPa) YS (MPa)

EL (%)

Corrosion r e s i s t a n c e E x f o l i a t i o n c o r r o s i o n I n t e r g r a n u l a r c o r r o s i o n

S t r e s s c o r r o s i o n Short transverse d i r e c t i o n

One may n o t i c e t h e h i g h l e v e l s o f TS and YS f o r t h e T6 temper and t h e good r e s u l t s o f EXCO and i n t e r g r a n u l a r c o r r o s i o n t e s t s f o r t h e T7x temper.

One c o n d i t i o n o r t h e o t h e r may be choosen according t o t h e f i n a l use of t h e p a r t . 1.4 8090 a l l o y

Table 3 shows t h e r e s u l t s obtained f o r an A320 window frame ( f i g . 2) u s i n g 8090 T6x.

They a r e compared w i t h r e s u l t s taken from t h e same p a r t u s i n g 2091 T7x.

T6

520 440 10 470 390 7

E~

250 - 400 j ~ m

4~ 100 MPa

The 8090 T6x provides a h i g h s t r e n g t h and a c o r r o s i o n r e s i s t a n c e e q u i v a l e n t t o t h a t o f conventional a l l o y s .

T7x

450 365 8,5 430 330 695

E~

30 - 150 ~ r n 2 1 7 5 MPa

Table 3 : Average p r o p e r t i e s on Airbus window frame 2091 T7x / 8090 T6x Mechanical p r o p e r t i e s

L-T TS (MPa) YS (MPa)

EL (%)

E x f o l i a t i o n c o r r o s i o n I n t e r g r a n u l a r c o r r o s i o n

2091 T7x

445 360 6,5 E ~ / E ~ 100 - 200 yrn

8090 T6x

505 425 5,5 E ~ / E ~ 80 - 120 ) ~ m

However such a c o n d i t i o n r e s u l t s i n lower d u c t i l i t y ( l o s s o f 1 t o 3 % on f r a c t u r e elongation).

Both a l l o y s (8090 and 2091) show t h e same anisotropy w i t h a l o s s o f s t r e n g t h a t 60° C.

1.5 Conclusion

S t r i c t l y speaking, t h e replacement o f 7075 T73 p r e c i s i o n d i e f o r g i n g s by A1-Li p a r t s w i t h same p r o p e r t y l e v e l s i s n o t p o s s i b l e f o r t h e time being. But FORGEAL i s now a b l e t o o f f e r t h e t h r e e f o l l o w i n g p r o p e r t y combinations u s i n g 8090 and 2091 i n d i f f e r e n t tempers :

Table 4 : Comparison o f 2091 T6, 2091

t h r e e p o s s i b l e T7x, 8090 T6

proper combinations f o r p r e c i s i o n f o r g i n g s : The Aerospace i n d u s t r y w i l l choose s u i t a b l e a l l o y and-temper according t o t h e r e q u i - r e d working c o n d i t i o n s o f each p a r t .

2

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F i g . 3 shows an a i r c r a f t wheel u s i n g 8090 a l l o y . The t y p i c a l l e v e l s o f mechanical p r o p e r t i e s obtained under T6 c o n d i t i o n f o r t h i s p a r t a r e i n t h e f o l l o w i n g t a b l e :

Table 5 : T y p i c a l mechanical p r o p e r t i e s D i r e c t i o n

Long Transverse

One may see t h a t TS and YS a r e s a t i s f a c t o r y as compared w i t h values o b t a i n e d u s i n g conventional a l l o y s , b u t f r a c t u r e e l o n g a t i o n values a r e n o t s u f f i c i e n t mainly i n t h e transverse d i r e c t i o n .

W i t h i n t h e n e x t few months one o f FORGEAL's t a r g e t s f o r t h i c k products w i l l be t o im- prove t h e d u c t i l i t y i n t h e s h o r t transverse d i r e c t i o n by o p t i m i z i n g t h e q u a l i t y of metal, t h e p r o d u c t i o n processes and heat treatments.

TS ( M P ~ ) 510 490

YS (MPa) 470 450

EL ( % ) 4 2,5

C3-46 JOURNAL DE PHYSIQUE

2.2 2091 hand f o r q i n q s

Hand forged blocks of t h i c k n e s s e s ranging from 60 t o ~ 1 5 0 mm have been produced using 2091 a l l o y .

A l l c a r a c t e r i z a t i o n s were made a f t e r cold compression ( 3 % i n t h e s h o r t t r a n s v e r s e d i r e c t i o n ) immediatly a f t e r quenching.

O J , C

1352 12 H 0 H 11 H 2 4 H 48 H 17 I1 AGEING 135.C l4l.C I4S.C 150.C ISP'C IG04C TAEATYEI~IS

The t a b l e 6 shows t h e mechanical p r o p e r t i e s e v o l u t i o n a s a function of t h e ageing treatment. An important l o s s o f d u c t i l i t y a s w e l l a s a considerable reduction i n t h e p l a s t i c f i e l d w i l l appear when t h e maximum T6 hardness i s reached.

1s lW#l

I f t h e replacement of conventional a l l o y s i s forseen, then two c o n d i t i o n s may be con- s i d e r e d :

'ts lW.#

so0 .

4SO .

4 0 0 .

350 .

so0 .

-

Two p r o p e r t i e s still remain a t a low l e v e l ( a s f o r t h e 8090 a l l o y ) ( s e e t a b l e 7 ) : t h e f r a c t u r e elongation i n t h e s h o r t t r a n s v e r s e d i r e c t i o n and t h e f r a c t u r e though- ness i n t h e S-L d i r e c t i o n .

4-

+

.

+ + + ^{4- 4. .I_}

+

+ +

'

'

Table 6 : Ageing curve on forged blocks

o e

a

8 Thickness 120 mm

Cold comressed irnmediatly a f t e r quenching : 3 %

S-T

Table 7

The stress corrosion resistance in the short transverse direction is equivalent to that of 2214 T6 alloy, hence not sufficient enough to allow the replacement of the 7000 series alloys.

The T8x52 condition corresponding to an ageing treatment of 12 H at 135O C, which is sufficient to obtain the property levels of 2024 T352 for thickness up to 150 mm (see table 8).

Table 8

2.3 Conclusion

Under heat treatment conditions reaching the maximum strength, the 2091 and 8090 alloys show an insufficient ductility in the short transverse direction in the both cases of hand forgings and die forgings.

Research work is going on to replace high strength alloys such as 2214 or 7xxx.

On the other hand, under T8x52 cohdition, 2091 alloy shows properties equivalent to those of 2024 T352 for plates and forged parts.

3

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Based on all the above results the precise use of A1-Li forgings is still being in- vestigated with customers, with attractive property combinations already available for some applications.

(3-48 JOURNAL DE PHYSIQUE

F i g . 1 Selection of Al-Li precision die forgings - Courtesy of AMD/BA

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Fi g.2 Airbus A320 Window frame F i g . 3 Aircraft wheel using 8090 C o u r t e s y of AEROSPATIALE courtesy of MESSIER-HISPANO-BUGATTI