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MAGNESIUM
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ABOUT MAGNESIUM
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Magnesium is the ideal material for applications where weight saving is a priority, having the lowest density of all structural metals. Almost as light in weight as plastic, magnesium has the advantage of greater strength and rigidity along with inherent EMI shielding, durability, heat-dissipation and full recyclability.

Magnesium is:

  • a quarter the weight of steel
  • one third lighter than aluminium
  • has the best strength to weight ratio of common structural metals
  • has exceptional die-casting characteristics

Magnesium is the metal of the future and today with the die casting demand for use in the automotive sector expected to double in the next decade.

Magnesium (Mg) is the eighth most abundant element and the sixth most common metal in the earth's crust. It comprises about 2.5 percent of the composition of the earth's surface but does not occur naturally in its metallic form.

Magnesium is a necessary element for all living organisms both animal and plant. Chlorophyll, the photo-synthetic green material in plants is structured around a magnesium atom, while in animals, magnesium is a key component of bones and tissues. Magnesium is the lightest of all structural metals and has a melting point of 650 degrees centigrade, its major attributes are:

  • USES: Magnesium is non-toxic, non-magnetic, and used in car parts, laptop computers, mobile phones and power tools.
  • WEIGHT: Lightest of all structural metals, 75 percent lighter than steel and 33 percent lighter than aluminium
  • STRENGTH: Has exceptional strength to weight ratio of load bearing parts to steel and aluminium
  • DIE CASTING: Molten magnesium viscosity makes for improved die-casting for larger more complex components
  • VIBRATION: Excellent ability to absorb energy vibration, acts as a damper and is highly dent resistant
  • ENVIRONMENT: Lightweight parts are the key to reducing vehicle weight and therefore improving automotive fuel efficiency and reducing greenhouse gas emissions
Magnesium alloy characteristics:
  • The lightest of all structural metals
  • Excellent stiffness and strength-to-weight ratio
  • Outstanding EMI shielding properties
  • High conductivity, electrical and thermal
  • Withstands high operating temperatures
  • Cost-effective against plastics
  • High dimensional accuracy and stability
  • Exceptional thin wall capability
  • Good environmental corrosion resistance
  • Good finishing characteristics
  • Full recyclability

 

  


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TECHNICAL DATA
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Characteristic physical properties of magnesium alloys

Property

Unit

Temperature

Magnesium alloys

AZ91

AM60

AM50

Density

kg/m3

20°C

1810

1800

1770

Liquidus temperature

°C

  

598

615

620

Melt-on temperature

°C

  

420-435

420-435

420-435

Linear expansion

um/m

20-100°C

26

26

26

Thermal conductivity

W7(k-m)

20°C

51

61

65

Electrical conductivity

MS/m

20°C

6,6

-

9,1

Mechanical properties of magnesium alloys

Property

Unit

Magnesium alloys

AZ91

AM60

AM50

Tensile strength Rm

MPa

240 (250)

225 (240)

210 (230)

Permanent elongation limit Rp02

MPa

160 (160)

130 (130)

125 (125)

Crushing yield point

MPa

160

130

125

Breaking elongation

%

3 (7)

8 (13)

10 (15)

Modulus of elasticity

GPa

45

45

45

Modulus of elasticity in shear

GPa

17

17

17

Brinell hardness

 

70

65

60

Impact strength Charpy, without notch

J

6 (9)

17 (18)

18 (18)

Mechanical properties of magnesium alloys with room temperature. The values in brackets show the property values for test bars cast separately.

Shearing resistance and compression resistance of die casting alloys

Material group

Shearing resistance N/mm2

Compression resistance N/mm2

Aluminium alloys

0,8 x tensile strength

1,5 x tensile strength

Zinc alloys

0,8 x tensile strength

1,5 x tensile strength

Magnesium alloys

0,5 to 0,8 x tensile strength

2,0 x tensile strength

Shearing resistance and compression resistance of die casting alloys

Further material properties of die casting alloys

Material group

E-Module kN/mm2

Coefficient of thermal expansion 20 to 100°C um

Melting range °C

Specific thermal capacity kW'S

Electrical conductivity S ° m

Thermal conductivity W

m'K

K'g

mm2

K'cm

Aluminum alloys

68... 78

20.... 24

510... 645

0,96

12... 28

0,84... 1,63

Zinc alloys

80... 85

27

380 ... 390

0,102... 0,108

15... 16

0,92 ... 1,05

Magnesium alloys

40... 45

26

470 ... 620

1

6... 10

0,50 ... 0,84

The values are reference values and depend on the composition of the alloy and on its microstructural status.

Machining of magnesium parts

From all well-known design metals, magnesium and its alloys are the easiest to machine. Advantages:

  • low specific cutting forces and therefore low energy required
  • high tool lives
  • short chips caused by the formation of shearing chips
  • high surface quality
  • high cutting speeds and therefore higher forward feeds.

Magnesium alloys can be machined with higher speed and higher forward feeds than other metals. These advantages reduce the cost of machining considerably by: Lower invest in machines and tools, lower machine and working costs and less scrap.

 

  
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