Dec 20 2012
Topics Covered
IntroductionPhysical PropertiesMechanical PropertiesThermal PropertiesOther DesignationsFabrication and Heat Treatment Machinability Forming WeldingApplications
Introduction
Zirconium is a strong, ductile and malleable metal whose physical and chemical properties are similar to that of titanium. It has good corrosion and heat resistance. At elevated temperatures, the finely divided metal is capable of igniting spontaneously in air. It cannot be dissolved in acids or alkalis. Zirconium is used in oxide or zirconia form. Zirconium oxide has low thermal conductivity and high melting point.
The following section will describe in detail about zirconium.
Physical Properties
The physical properties of zirconium are outlined in the following table.
| Properties |
Metric |
Imperial |
| Density |
6.53 g/cm³ |
0.236 lb/in³ |
| Melting point |
1843°C |
3350°F |
Mechanical Properties
The mechanical properties of zirconium are outlined in the following table.
| Properties |
Metric |
Imperial |
| Tensile strength (annealed) |
330 MPa |
47900 psi |
| Yield strength (annealed) |
230 MPa |
33400 psi |
| Modulus of elasticity |
94.5 GPa |
13700 ksi |
| Poissons ratio |
0.34 |
0.34 |
| Elongation at break (annealed) |
32% |
32% |
| Hardness, Brinell (converted from Vickers for 3000 kg load/10 mm ball. Annealed sample) |
145 |
145 |
| Hardness, Rockwell A (converted from Vickers. annealed sample) |
49 |
49 |
| Hardness, Rockwell B (converted from Vickers. Annealed sample) |
78 |
78 |
| Hardness, Vickers (annealed sample) |
150 |
150 |
Thermal Properties
The thermal properties of zirconium are outlined in the following table.
| Properties |
Metric |
Imperial |
| Thermal expansion coefficient (@20-100°C/68-212°F) |
5.80 µm/m°C |
3.22 µin/in°F |
| Thermal conductivity |
16.7 W/mK |
116 BTU in/hr.ft².°F |
Other Designations
Other designations that are equivalent to zirconium include the following:
- ASTM B493
- ASTM B494
- ASTM B523
- ASTM B550
- ASTM B551
- ASTM B653
- ASTM B658
- AWS A5.24
Fabrication and Heat Treatment
Machinability
Zirconium must be machined carefully as the zirconium powder and shavings are flammable. Hence, a flood cooling system, heavy feed and slow speeds are required. The metal also has a tendency to gall.
Forming
Zirconium is ductile and easily workable. However, proper lubricant must be used to prevent galling.
Welding
Gas tungsten arc welding method is best-suited for welding zirconium. Proper shielding is required for welding zirconium, which may otherwise result in weak and brittle welds.
Applications
The following are the major applications of zirconium.
- Jet engines
- Knife blades
- Water-cooled nuclear reactors
- Super alloys
- Chemical processing equipment