2A70 is a short heat-resistant Al-Cu-Mg-Fe-Ni alloy, which can be strengthened by heat treatment. The alloy has high heat resistance and service temperature of 200-250 ℃. The plasticity in hot state is high and there is no backlog effect. The corrosion resistance of the alloy is acceptable, but it has a profitable corrosion tendency. Its weldability is medium, suitable for resistance spot welding and seam welding, but the performance of arc welding and gas welding is poor. Its machinability is good.


 
2A70 aluminium alloy is used to manufacture piston of internal combustion engine and complex forgings working at 200-250℃, such as compressor impeller, blower impeller, etc. Plate can be used as structure parts at above temperature, and its use is more extensive than another kind of heat-resistant forging aluminium 2A80.
 

Mechanical properties of 2A70 aluminium alloy forgings specified in technical standards
	Temper	Direction	Tension strength Rm/MPa	Prescribed plastic elongation strength  Rp0.2/MPa	Elongation A (%)
Free forgings	T6	Portrait	375	－	5.0
	T6	Long transverse	375	－	5.0
Die forgings	T6	Portrait	380	275	5.0
	T6	Long transverse	380	275	5.0

 
 

Tensile Properties of 2A70 Aluminum Alloy Forgings Stabilized at Room Temperature
Temper	Stabilization treatment		Tension strength Rm/MPa	Elongation strength RP0.2/MPa	Elongation A (%)
	Temperature/℃	Holding time/h
Free forgings and Die forgings	125	100	431	333	10
		1000	431	333	8
		10000	431	333	8
	150	100	431	333	9
		1000	431	333	9
		10000	431	333	9
	175	100	421	353	8
		1000	402	353	8
		10000	397	353	7

 
2A70 aluminium alloy is prone to over-burning. The over-burning temperature is 545 ℃. Therefore, the heating temperature should be strictly controlled during forging and solution heat treatment. The Brinell hardness of the alloy is 130-139HBW under T6, 139HBW for small forgings and 130HBW for neutral forgings.


 
The forging performance of 2A70 aluminium alloy is good. It can be forged by hammer forging or by hydraulic press. The forging temperature of the alloy ranges from 450 to 350 ℃
 

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