7A04 alloy is a heat-treated strengthening alloy of Al-Zn-Mg-Cu system. Its strength is higher than that of hard aluminium. Its yield strength is close to tensile strength and its plasticity is lower. Its sensitivity to stress concentration is strong, especially under the condition of vibration load and repeated static load. Therefore, the design, manufacturing and assembly of parts need to strictly avoid stress concentration and additional stress factors. The heat resistance of the alloy is poor, and it will soften sharply when the temperature is higher than 125 C. The stress corrosion resistance of thick parts in short and transverse direction is poor.
 
7A04 aluminum forgings forged product parts is widely used in the main stress parts of aircraft structure, such as girder, truss, partition frame, skin, wing rib, joint, landing gear parts, etc. It can produce various semi-finished products, such as sheets, strips, profiles, bars, wallboards, pipes, wires, free forgings and die forgings.

Chemical Composition of 7A04 aluminum alloy

Alloy

Si

Fe

Cu

Mn

Mg

Cr

Ni

Zn

Ti

Zr

Others

Al

Single

Total

7A04

0.50

0.50

1.4~2.0

0.20~0.60

1.8~2.8

0.15~0.25

－

5.0~7.0

－

－

0.05

0.15

Rest

 
 

Alloy	Alloy series	Main features	Σb Value/MPa	Working temperature/℃
7A04	B95(Russia）	Yield strength is close to tensile strength, plasticity is low, and sensitivity to stress concentration is strong, especially under the condition of vibration load and repeated static load. Therefore, stress concentration and additional stress factors should be strictly avoided in the design, manufacture and assembly process of parts. The short transverse Kang stress corrosion resistance of the heavy alloy parts is poor.	480~570	<125

Physical Property of 7A04 aluminum forgings forged product parts
Alloy	Type	Temper	δ Specs/mm	Direction	σb/MPa	σp 0.2/MPa		δ %	Standard
7A04	Free forgings	T6	Weight ≤30KG	L	510		420	6	GJB 2351-1995
			Weight>30KG	L	510		420	5
	Die forgings	T6	Weight≤30KG	L	530		440	6
			Weight>30KG	L	430		440	6

 

Alloy	Temper	Aircraft type	Application parts and typical part
7A04	Aluminum forgings forged product parts：T6、T652、T73、T7352	Y8， Y12	Skin, wallboard, all kinds of beams (backlogs, forgings), partition frame, wing ribs, long truss, joints, landing gear parts, etc.

 
 

Type	Alloy	Projected area （m2）Or weight（kg）	Temper	Standard
Aluminum free forgings	5 series	≤3000kg	O、F	GBn223     ASTMB247
	2、6、7 series	≤3000kg	T6、T4、O、F
Aluminum die forgings	5 series	≤2.5m2	O、F
	2、6、7 series	≤2.5m2	T6、T4、O、F

 



7049 aluminium forgings forged product parts are generally used to manufacture parts with the same static strength as 7079-T6 alloy and high stress corrosion cracking resistance, such as landing gear box, hydraulic cylinder and extrusion parts of aircraft and missile parts. The fatigue property of the parts is approximately the same as that of 7075 T6 alloy, but the willfulness is slightly higher.
The general states of 7049 aluminium forgings forged product parts are F, T6, T652, T73 and T7352.
On the basis of 7001 alloy, the content of alloying elements Cu and Cr is reduced, the ratio of Zn/Mg is increased, and the content of impurities Fe and Si is reduced. It is mainly used to produce forgings and backlogs in T73 state, as well as thick and thin plates. The stress corrosion crack growth rate of 7075 T6 alloy is much lower than that of 7075 T651 alloy.
 

7049 Aluminum Chemical Composition

Alloy

Si

Fe

Cu

Mn

Mg

Cr

Ni

Zn

Ti

Zr

Others

Al

Single

Total

7049

0.25

0.35

1.2~1.9

0.20

2.0~2.9

0.10~0.22

~

7.2~8.2

0.10

~

0.05

0.15

Rest

 
 
 
 
 
 
 
 
 
 

Alloy temper	Main features	Main products and status	Application parts and typical parts
7049	The alloy for the purpose of replacing 7079 has high strength, good SCC resistance and poor corrosion resistance.	T73，T7352，T6，T652	Aircraft main landing gear, missile accessories.

 
 
 

Type	Alloy	Projected area（m2）or weight（kg）	Temper	Standard
Aluminum free forgings	5 Series	≤3000kg	O、F	GBn223     ASTMB247
	2、6、7 Series	≤3000kg	T6、T4、O、F
Aluminum die forgings	5 Series	≤2.5m2	O、F
	2、6、7 Series	≤2.5m2	T6、T4、O、F

7050 is a high strength Al-Zn-Mg-Cu alloy, which can be strengthened by heat treatment. On the basis of 7075 superhard aluminium alloy, the chemical composition of the alloy was adjusted, the content of zinc and copper was increased, the grain was refined by zirconium instead of chromium, and the content of impurities such as silicon and iron was reduced. Due to the optimization of chemical composition and the over-aging treatment, the aluminium alloy has high fatigue limit, good toughness, good stress corrosion resistance and good hardenability while maintaining high strength. Its hot working performance is similar to 7075 alloy. It has general weldability and good cutting property.
 
77050 is mainly used for high strength, good fracture toughness, and high stress corrosion cracking resistance and spalling corrosion of the main bearing structural parts, such as aircraft structure with thick plates, extrusions, free forgings and die forgings, such as aircraft structure with thick plates, extrusions, free forgings and die forgings, including fuselage frames, partitions, wing beams, landing gear support parts and rivets. Because the alloy has good hardenability, it is especially suitable for manufacturing large thick section parts. The supply state of the aluminum alloy includes T74, T76 and T73. T74 should be selected for structural parts requiring high strength and stress corrosion cracking resistance; T76 should be generally used for structural parts requiring high strength and anti-spalling corrosion; and T73 is mainly used for rivet materials requiring high strength and good corrosion resistance.
 

The Brinell hardness of 7050 aluminium alloy forging in T74 state is 158HBW.
7150 T77 aluminium forging forged product parts are an improved 7050 Alloy with high strength and good corrosion resistance. The fatigue resistance of 7150 T651 is 10%-15% higher than that of 7075, and the fracture toughness is 10% higher. The SCC resistance of 7150 T651 is similar to that of 7075. Mainly used in large passenger aircraft upper wing structure, body plate girder flange, upper outer panel main wing longitudinal beam, fuselage reinforcement, keel beam, seat guide rail.
 
Reduce heat treatment stress and avoid quenching deformation.
After solution treatment, the free forgings should be pre-compressed before artificial aging, and the permanent deformation is 1.5%-5.0%, so as to eliminate the internal stress.
The formability of the alloy is similar to that of 7075 aluminium alloy. If the initial forging temperature is too high, hot forging is easy to occur, which is disadvantageous to the hammer forging process.
 

Tensile Properties of 7050 Aluminum Alloy T73652 Free Forging at Room Temperature
Thickness/mm	Direction	Tension strength Rm/MPa	Prescribed plastic elongation strength Rp0.2/MPa	Provision of non-proportional compressive strength Rpc0.2/MPa	Elongation A (%)
≤50	Portrait	496	434	441	9
	Long transverse	490	421	448	5
>50--75	Portrait	496	427	434	9
	Long transverse	483	414	441	5
	Short transverse	462	379	421	4
>50--110	Portrait	483	421	427	9
	Long transverse	476	407	434	5
	Short transverse	455	379	421	4

 

7050 7150 Chemical Composition

Alloy

Si

Fe

Cu

Mn

Mg

Cr

Ni

Zn

Ti

Zr

Others

Al

Single

Total

7050

0.12

0.15

2.0~2.6

0.10

1.9~2.6

0.04

~

5.7~6.7

0.06

0.08~0.15

0.05

0.15

Rest

7150

0.12

0.15

1.9~2.5

0.10

2.0~2.7

0.04

~

5.9~6.9

0.06

0.08~0.15

0.05

0.15

Rest

 
 
 
 
 
 

Room Temperature Tensile Properties of Aluminum Alloy T736 State Die Forging
Thickness/mm	Direction	Tension strength Rm/MPa	Prescribed plastic elongation strength Rp0.2/MPa	Provision of non-proportional compressive strength Rpc0.2/MPa	Elongation A (%)
≤50	portrait	496	427	434	7
	transverse	469	386	400	5
>50--100	portrait	490	421	434	7
	transverse	462	379	393	4
>100--125	portrait	483	414	434	7
	transverse	455	372	379	3

 

Tensile Properties of 7050 Aluminum Alloy T736 State Die Forging at Room Temperature
Thickness/mm	Direction	Tension strength Rm/MPa	Prescribed plastic elongation strength Rp0.2/MPa	Provision of non-proportional compressive strength Rpc0.2/MPa	Elongation A (%)
≤50	portrait	496	427	434	7
	transverse	469	386	400	5
>50--100	portrait	490	421	434	7
	transverse	462	379	393	4
>100--125	portrait	483	414	434	7
	transverse	455	372	379	3

 
 
 

Low Temperature Tensile Properties of 7050 Aluminum Alloy Forgings
Alloy Temper	Temperature	Tension Strength Rm/MPa	Prescribed plastic elongation strength  Rp0.2/MPa	Elongation A (%)
7050  T73652	-195	662	572	13
	-80	586	503	14
	-28	552	476	15

 
 

Tensile Properties of 7050 Aluminum Alloy Forgings at High Temperature
Alloy Temper	Temperature/℃	holding time/h	Tension Strength Rm/MPa	Prescribed plastic elongation strength Rp0.2/MPa	Elongation A (%)
7050  T73652	24	-	524	455	15
	100	0.1--10	462	427	16
		100	469	434	16
		1000	462	427	17
	150	0.1	414	386	17
		10	407	386	18
		100	365	352	20
		1000	290	276	23
	175	0.1	379	345	19
		10	324	310	22
		100	248	234	25
		1000	193	172	31
	205	0.1	324	290	22
		10	221	207	27
		100	165	152	32
		1000	131	110	45

 

Room Temperature Shear Properties of 7050 Aluminum Alloy Forgings
	Temper	Shear strength of the following thickness  MPa
		≤50mm	>50--100mm	>100--125mm
Aluminum free forging	T73652	290	283	283
Aluminum die forging	T736	290	283	283

 
 

Type	Alloy	Projected area（m2) or Weight（kg）	Temper	Standard
Aluminum free forging	5 series	≤3000kg	O、F	GBn223     ASTMB247
	2、6、7 series	≤3000kg	T6、T4、O、F
Aluminum die forging	5 series	≤2.5m2	O、F
	2、6、7 series	≤2.5m2	T6、T4、O、F

 
 
7055 aluminium forgings forged product parts are generally used in the T77 state to manufacture aircraft load-bearing structural parts recently produced, such as 7055 T77511 for the upper wing panel of ARJ21-700 regional airliner being manufactured in China, 7055-T77 for landing gear joints and 7055 T76511 for the long truss of the fuselage. 7055 super-strength aluminium alloy is the highest strength alloy in wrought aluminium alloy at present. The microstructure of 7055 alloy is resistant to intergranular cracking and corrosion, and its microstructure has strong ability to hinder dislocation movement.
 
7055 T77 aluminium forgings forged product parts are generally used in large aircraft upper wing skin, truss, horizontal tail, keel beam, seat rail, freight slide. Compressive strength and tensile strength are 10% higher than 7150, and fracture toughness and corrosiveness are similar to 7150.

7050 Alloy Chemical Composition

Alloy

Si

Fe

Cu

Mn

Mg

Cr

Ni

Zn

Ti

Zr

Others

Al

Unit

Total

7055

0.10

0.15

2.0~2.6

0.05

1.8~2.3

0.04

~

7.6~8.4

0.06

0.05~0.25

0.05

0.15

Rest

 
 
 
 

Alloy	Alloy sereis	Main features	Σb Value /MPa	Working temperature/℃
7055	7050 series	7055 is currently the highest alloying degree of 7 x x x series aluminium alloy. Compared with 7150 alloy, it improves tensile and compressive strength while maintaining some important properties such as fracture toughness and corrosion resistance.	643～669	<125

Type	Alloy	Projected area（m2）Or weight（kg）	Temper	Standard
Aluminum free forging	5 series	≤3000kg	O、F	GBn223     ASTMB247
	2、6、7 series	≤3000kg	T6、T4、O、F、T77
Aluminum die forging	5 series	≤2.5m2	O、F
	2、6、7 series	≤2.5m2	T6、T4、O、F、T77

 
 
7175 improves the purity of 7075 alloy. It is mainly used as die forgings. It has three heat treatment states: T66, T74 and T7452. Among them, the static strength of T66 forging is higher than that of 7075 T6 forging, while fatigue, crack resistance and stress corrosion resistance are equivalent. The static strength of T74 die forging and free forging is similar to that of 7075 T6 forging, and the stress corrosion resistance balance is between 7075 T73 and 7075 T76, while the toughness and fatigue properties are comparable to or even better than 7075 T73 forging. The stress corrosion resistance of T74 state is obviously higher than that of 7075 T6 state, approaching 7075 T73 state.
 
7175 alloy is specially used to produce forgings and rolling rings. The material state is T74. The characteristics of 7175 T74 aluminium alloy forgings are that special processing and heat treatment processes are adopted to make the strength close to 7075 T6 alloy forgings and the stress corrosion resistance close to 7075 T73 forgings in the best corrosion state. The reduction of Fe and Si rolling can not only improve the forging properties of the alloy, but also significantly improve the stress corrosion resistance and fracture toughness of the forgings.
 

7175 7075 Aluminum Alloy Chemical Composition

Alloy

Si

Fe

Cu

Mn

Mg

Cr

Ni

Zn

Ti

Zr

Others

Al

Single

Total

7175

0.15

0.20

1.2~2.0

0.1

2.1~2.9

0.18~0.28

~

5.1~6.1

0.10

~

0.05

0.15

Rest

7075

0.40

0.50

1.2~2.0

0.3

2.1~2.9

0.18~0.28

~

5.1~6.1

0.20

~

0.05

0.15

Rest

7075 aluminium forgings are high strength deformed aluminium alloys strengthened by heat treatment at any time. They can produce products of various kinds and sizes. They are the most widely used high strength aluminium alloys at present. It has several heat treatment states: T6, T73 and T76. The strength of T6 state is the highest, but the fracture toughness is low.

Technical Indicators for 7075 T74 Aluminum Alloy Forging
Direction	Rm/MPa	Rp0.2/MPa	A5/%	KIC/(N.mm-2).m1/2	Conductivity/（MS.m-1）
portrait	490	420	9	33.0	22.6
Long transverse	483	400	5	27.5
Section transverse	469	393	4	23.1

 

Calibrated Mechanical Properties of 7175 T74 Alloy Rolled Forged Ring (YS/T 478)
Direction	Thickness/mm	Tension Strength Rm/MPa	Yield strength Rp0.2/MPa	Elongation A5/%
L	<80	≥505	≥435	≥8

 
 

Alloy	Temper	Aircraft model	Application parts and typical parts
7175	T74	A320、Z10、EC120 etc。	Front edge, window frame, fairing joint, control parts, etc.

 

Type	Alloy	Projected area（m2）Or weight（kg）	Temper	Standard
Aluminum free forging	5 series	≤3000kg	O、F 、T74	GBn223     ASTMB247
	2、6、7 series	≤3000kg	T6、T4、O、F
Aluminum die forging	5 series	≤2.5m2	O、F
	2、6、7series	≤2.5m2	T6、T4、O、F、T74