Elektron® RotaMag®

Elektron® RotaMag® forgings can be used where pressure tightness or machinability are required. Parts that are dimensionally stable during and after machining is also an important design consideration.

Forgings in Elektron® RotaMag® find application in high strength parts for:

• Satellites
• Helicopter gearboxes and rotor hubs
• Bicycle frames
• Roadwheels
• Missile frames and interstage fairings
• Brake housings
• Landing gear struts

• Uns No. M11800
• AMS4360
• ASTM B91-12
• FEDERAL QQ-M-40B

Aluminium: 7.8–9.2%
Zinc: 0.2–0.8%
Manganese: 0.12–0.5%
Magnesium: Balance

Billets are normally provided fully homogenised to promote ease of forging.

Specific gravity: 1.8
Coefficient of thermal expansion: 26 x 10^-6K^-1
Thermal conductivity: 76 Wm^-1K^-1
Specific heat: 1,100 Jkg^-1K^-1
Electrical resistivity: 145 nΩm
Modulus of elasticity: 45 GPa
Poissons ratio: 0.35
Melting range: 470–595˚C

Specification minimum tensile properties.

AZ80A-T5 die forgings

0.2% proof stress: 193 MPa
Tensile strength: 290 MPa
Elongation: 2%

AZ80-F die forgings

0.2% proof stress: 179 MPa
Tensile strength: 290 MPa
Elongation: 5%

The grain refinement of forging billets is a key factor affecting the ease of which the metal can be forged. Elektron® RotaMag® forging billet undergoes a special grain refining process to ensure a fine uniform structure. Grain size is controlled to below 200 µm for 300 mm diameter billet.

Elektron® RotaMag®, like all magnesium alloy forgings, machines faster than any other metal. Providing the geometry of the part allows, the limiting factor is the power and speed of the machine rather than the quality of the tool material. The power required per cubic centimetre of metal removed varies from 9 to 14 watts per minute depending on the operation.

All the normal chromating, anodizing, plating and finishing treatments are readily applicable.

As-fabricated (F) forgings can be converted to the precipitation treated temper T5 by heating to 177˚C for 16–24 hours, followed by air cooling.