Nov 12 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesMechanical PropertiesThermal PropertiesOther DesignationsFabrication and Heat Treatment Machinability Forming Welding Heat Treatment Hot Working AgingApplications
Introduction
Magnesium is a silvery-white metal which is used as an alloy element for zinc, lead, aluminum, and other nonferrous alloys. Magnesium alloys are designated using the ASTM and SAE system in which the first part denotes the two main alloying elements in the alloy and the second part represents their percentages. They are light weight and have high machinability. They are anodized to enhance their corrosion resistance property.
Magnesium ZK60A alloy is a heat treatable magnesium alloy. It has higher ductility than magnesium AZ60A alloy.
The following datasheet gives an overview of magnesium ZK60A alloy.
Chemical Composition
The following table shows the chemical composition of magnesium ZK60A alloy.
| Element |
Content (%) |
| Magnesium, Mg |
94 |
| Zinc, Zn |
4.80-6.20 |
| Zirconium, Zr |
≥ 0.45 |
Physical Properties
The physical properties of magnesium ZK60A alloy are given in the following table.
| Properties |
Metric |
Imperial |
| Density |
1.83 g/cm3 |
0.0661 lb/in³ |
Mechanical Properties
The mechanical properties of extruded magnesium ZK60A alloy are listed in the following table.
| Properties |
Metric |
Imperial |
| Tensile strength |
365 MPa |
52900 psi |
| Yield strength (@ strain 0.200%) |
305 MPa |
44200 psi |
| Compressive yield strength (at 0.2% offset) |
250 MPa |
36300 psi |
| Ultimate bearing strength |
585 MPa |
84800 psi |
| Bearing yield strength |
405 MPa |
58700 psi |
| Shear strength |
180 MPa |
26100 psi |
| Shear modulus (typical for steel) |
17 GPa |
2470 ksi |
| Elastic modulus |
44.8 GPa |
6498 ksi |
| Poisson's ratio |
0.35 |
0.35 |
| Elongation at break (in 50 mm) |
11% |
11% |
| Hardness, Brinell (500 kg load, 10 mm ball) |
88 |
88 |
| Hardness, Knoop (estimated from Brinell) |
113 |
113 |
| Hardness, Rockwell A (estimated from Brinell) |
37.5 |
37.5 |
| Hardness, Rockwell B (estimated from Brinell) |
55 |
55 |
| Hardness, Vickers (estimated from Brinell) |
100 |
100 |
| Machinability (relative rating, 100=best) |
100 |
100 |
Thermal Properties
The following table outlines the thermal properties of magnesium ZK60A alloy.
| Properties |
Metric |
Imperial |
| Thermal expansion co-efficient (@ 0-100°C/32-212°F) |
26 µm/m°C |
14.4 µin/in°F |
| Thermal conductivity |
120 W/mK |
833 BTU in/hr.ft².°F |
Other Designations
Other designations that are equivalent to magnesium ZK60A alloy include:
Fabrication and Heat Treatment
Machinability
Magnesium ZK60A alloy has high machinability. It is flammable and a lubricant is used to perform this operation. The machinist is required to constantly monitor the operation with a magnesium fire arresting kit.
Forming
Magnesium ZK60A alloy can be formed by preheating at 260°C (500°F).
Welding
Magnesium ZK60A alloy can be welded using resistance welding method. Arc welding method is not preferred for welding this alloy.
Heat Treatment
Magnesium ZK60A alloy is heat treated at 499°C (930°F) for 2 h followed by quenching in hot or warm water.
Hot Working
Magnesium ZK60A alloy can be hot worked at 260°C (500°F).
Aging
Magnesium ZK60A alloy is aged at 149°C (300°F) for 24 h.
Applications
Magnesium ZK60A alloy is used in different aircraft applications such as brake housings, instrumentation bodies, landing gear, ribs and spars.