MAIN ALUMINIUM ALLOYS

The following table is giving the main designations of the 6 welding alloys, except for the 4000 family, and comparing the french designations to the others.

4. Influence of conditions of manufacture - metallurgical States

The alloys of families 2000, 6000 and 7000 can be hardened by heat treatment of solution treatment and quenching, followed by a age hardening which is made :
- either at the ambient temperature (maturation or natural ageing),
- or by heating (returned or accelerated maturation or artificial ageing).
The solution treatment, thermal treatment at high temperature can be done in a furnace, but for certain alloys, in particular those of family 6000, it can be done during an operation of hotworking.

The table below gives the standardized designation of the states valid in France and in Europe.

Operations	treatment in furnace	Hotworking
Quenching + natural ageing	T4	T1
Quenching + artificial ageing	T6	T5

Alloys and delivery states typical characteristics

The table below gives typical values of the composition and a certain number of physical properties of alloys usually used.

Alloy	Composition in %								Voluminal mass kg.dm-3	Electric conductivity %IACS	Thermal conductivity W.m-1.K-1
	Fe	Si	Cu	Mn	Mg	Cr	Zn	Pb
6082		1,00		0,7	0,9				2,71	41	174

The table below gives typical values of the mechanical characteristics, properties of implementation and standard application of these alloys.

Alloy	State	Mecanical Characteristics			Corrosion resistance	Welding Aptitude	Machining	Aptitude for the deformations	Aptitude for anodising	Applications
		Rm MPa	Rp02 MPa	A%
1050A	O	80	30	42	A	A	C	A	A	Building, Kitchen
	H24	115	80	25	A	A	B	B	A
2017A	T4	420	280	18	C	D	A	C	C	Gen. Mech.
2024	T3	465	320	18	C	D	B	D	C	Aeronautics
2030	T3	450	390	10	C	D	A	C	C	Free Machining
5083	O	305	160	23	A	A	C	B	A	Chemical,cryo transport
	H116	335	230	20	A	A	B	B	A
5086	O	278	135	25	A	A	C	B	A	Chemical, cryo C. naval
	H22	310	225	18	A	A	B	D	A
5754	O	220	100	23	A	A	C	B	A	Hollow ware, marine
	H24	270	215	10	A	A	B	D	A
6060	T5	220	190	16	A	B	C	C	A	Building
6082	T6	315	280	12	A	B	C	C	A	Transport
7075	T6	565	495	11	C	D	B	D	B	Aero

A : very good - B : good -C : medium -D : bad

Sommaire

Classification of alloys according to their use

Macining - Free Machining - welding - Structural uses

- corrosion resistance - Composition - Anodic Oxydation

Machining - Free Machining

Aluminium and its alloys are machined with facility with respect of taking some precautions at the high cutting speeds and of using adapted tools. The aluminium alloys are machined better than pure aluminium; it is in particular the case of alloys with age hardening. Generally, the alloys with high mechanical characteristics, and thus with low capacity of cold deformation cold, are machined well.

The best adapted alloys to machining are :
2017A T4, 2024 T3 ,2618A T851
5083 H111
6082 T6
7075 T651

The specific alloys for free machining contain lead or lead and bismuth (elements which support the fragmentation of the chip largely) are :
2011 T3, 2030 T3
6262 T9

Welding

If in a general way all the aluminium alloys are weldable, they do not behave all in an identical way; it is necessary to distinguish three classes from alloys:

* the alloys without age hardening (families 1000, 3000 and 5000) They have a good weldability; when they are used with the state annealed, they do not undergo a loss sensitive of mechanical characteristics on the welded parts. On the other hand when they are in a hammer-hardened state, the hardening due to work hardening disappears in the vicinity of the welding. Alloys - typical states are : 1050A O, 3003 O, 5083 H111, 5086 O; the addition of chromium in the last two alloys still improves their weldability.

* alloys with age hardening free from copper (family 6000 and certain alloys of family 7000).
The thermal cycle of welding affects the mechanical characteristics of the base metal which is generally in a quenched-tempered state; this loss is final for alloys of family 6000 except if it is possible to carry out a new treatment of income on the welded structure; the alloys of family 7000 find a notable part of their initial characteristics by maturation at the ordinary temperature.
The typical alloys are : 6060 T5, 6082 T6 ,7020 T5.

* The alloys with age hardening containing copper (family 2000 and certain alloys of family 7000)
These alloys are not easily weldable because, on the one hand, they are prone to the splits during the solidification of the welding, and, on the other hand, their mechanical characteristics after welding are strongly decreased. However these alloys are more or less sensitive to these phenomena: the 2618A T851 is not very sensitive to the splits. The use of process TIG with great concentration of energy and increased gas protection allows a notable improvement of the results.

Structural uses

The aluminium alloys are very much used for structural applications competing with steels. The elastic module of aluminium alloys, which the third of that of steels, led, to avoid too significant bendings, to increase the thicknesses of the sections compared to those of steels; so the reduction resulting from the replacement of steel by an aluminium alloy is not in the report/ratio of the densities but lies between 40 % and 60 %. However, the possibility of obtaining with aluminium alloys some complex profiles makes it possible to compensate for the weak elastic module of metal by a form of the profiles which leads to high moment of inertia.
Alloys - States most used : :
5083 H22, 5086 H24 ,5754 H24
6005A T5 ,6061 T6, 6082 T6
7020 T5

Corrosion Resistance

The aluminium alloys are famous to be well resistant to corrosion. However, under certain conditions of exposure, they can undergo a damage. This one can appear in various forms which depend on the composition of alloy and its metallurgical state.

Composition

* More the content impurities iron and silicon is weak, more aluminium and its alloys resist corrosion.
* The alloys of family 3000 resist as well corrosion as the aluminium of commercial purity.
* The alloys containing some copper (family 2000 and certain alloys of family 7000) resist corrosion badly.
* The alloys of family 5000 resist corrosion well if the magnesium content does not exceed 4 %. Beyond this content, it is necessary to treat thermically metal (H116 state).
* The alloys of family 6000 have a good behavior and this more especially as they have a very good aptitude for the anodization which forms a layer of thick and protective alumina.
* The alloys of family 7000 without copper resist corrosion well. Certain alloys with low zinc content are used like plating of protection of alloy 7000 sheets with copper intended for aeronautics.

Anodic oxydation

Anodic oxidation or anodization makes it possible to build an oxide coating much thicker than the natural alumina film; this layer confers thus on metal:
- a good protection against corrosion,
- an improvement of the aspect of surface, which will last in time; moreover the anodic layer can be coloured,
- a modification of several properties of surface such as for example: electric insulation, capacity reflectors, surface hardness, coefficient of friction.
The aluminium alloys do not lend themselves in a way identical to the treatment of anodization. The alloys most suited belong to families 1000, 5000 and 6000. The alloys containing of copper are with difficulty anodisables

Family 1000: the layer is all the more transparent as the contents iron and silicon are weak.
Family 2000: the layer has a limited thickness and is porous what decreases its protective capacity.
Family 3000: the layer has a more or less gray colour.
Family 5000: the layer is grey and depends on the other elements of addition (chromium and manganese).
Family 6000: the process of anodization is largely used in the metal fittings.
Family 7000: the conditions of anodization must be adjusted with the composition and the type of required protection.

Aluminium

Nominale Chemical Composition% :

Si	Fe	Cu	Mn	Mg	Cr	Zn	Ti	Al
0,40 à 0,80	max 0,70	0,15 à 0,40	max 0,15	0,8 à 1,2	0,04 à 0,35	max  0,25	max  0,15	Solde

Typical Mechanical characteristics :

Etat	Rp 0,2 hbar	RM hbar	A 5,65 %	HB brinell	densité
O	6	12	28	30	2,7
T4	13	23	23	65	2,7
T6	27	31	13	95	2,7

European Standards:

Composition : NF EN 573-1

NF A 02.104 : 6082 A
ISO : Al Si 1 Mg Mn

Aluminium

Nominal chemical composition % :

Si	Fe	Cu	Mn	Mg	Cr	Zn	Ti	Al
0,7 à 1,3	max 0,5	max 0,10	0,40 à 1,0	0,6 à 1,2	max 0,25	max  0,20	max 0,10	Solde

Typical Mechanical characteristics :

Etat	Rp 0,2 hbar	RM hbar	A 5,65 %	HB brinell	densité
T6	28	31	12	80/100	2,7

European standards:

Composition : NF EN 485-2

Mechanical characteristics :

-Bars, Tubes, Shaped Threads : NF EN 755-2

- Bars,Stretched Tubes : NF EN 754-2