All data is for information only------(Home)
	PRODUCT DATA of AA7178-T76

Material

AA7178-T76

General Information

Alloy 7178 is a high strength alloy with magnesium and copper as the major alloying elements. It is heat treatable and develops improved mechanical properties from precipitation hardening.

Chemical Composition

Al-0.25Cr-2.2Cu-2.7Mg-7Zn

	EXPERIENCE IN PRACTICE

Development Status

Commercial Product

Equivalent Designations

AA 7178

	PHYSICAL PROPERTIES

Crystal Structure

Face centered cubic (fcc)

Specific Gravity

2.83

Magnetic Properties

Nonmagnetic

	ELASTIC PROPERTIES

Tensile Modulus

71.7 GPa

Poisson Ratio

0.33

	THERMAL PROPERTIES

Thermal Conductivity

125 W/m.K

Thermal Expansion Coefficient

23.4 μstrain/°C

Specific Heat

0.856 J/g.K

Melting Range

477 to 629 °C

	RELEVANT PROPERTIES FOR USE IN SPACE COMMUNITY

General Corrosion Status

Requires specific corrosion protection

Stress Corrosion Status

Moderate Resistance to SCC: Table 2 Remark: Requires Stress corrosion evaluation form Data Quality: Design Data

EMF vs SCE

-0.74 V

Bimetallic Corrosion

Can be used in a non-controlled environment: Al alloys, Cd Can be used in a clean room environment: Mg, Sn-Pb alloys (all), Sn, Pb, Zn, Be Needs specific measures: All others Test:ECSS-Q-ST-70C Rev.1 Table 5.1 Data Quality: Design Data

Machinability

Machinability of this alloy is good, especially in the annealed condition. Use of oil lubrication during machining is recommended.

Aging

Precipitation heat treatment (Aging) is done at 121 CF for 24 hours to obtain T6 and T651 tempers.

Atomic Oxygen

No effect

	SPECIAL RECOMMENDATIONS

Lessons Learned

In some cases, this alloy responds poorly to black anodising.