Havar (alloy)
Havar, or UNS R30005, is an alloy of cobalt, possessing very high mechanical strength. It can be heat-treated. It is highly resistant to corrosion and is non-magnetic. It is biocompatible. It has high fatigue resistance. It is a precipitation hardening superalloy.
Havar is composed of 42.0% of cobalt, 19.5% of chromium, 12.7% of nickel, 2.7% of tungsten, 2.2% of molybdenum, 1.6% of manganese, 0.2% of carbon, 0.02-0.08% of beryllium, and balance of iron. Its melting point is about 1480 °C. It will retain three quarters of its room temperature strengths up to 510 °C. Its density is 8.3 g/cm3. Its thermal conductivity is 13.0 W/m·K. Its tensile strength is 960-970 MPa and its modulus of elasticity is 200-210 GPa. It can be joined by welding at 70 °C, and reaches rate of 56 mm/year at boiling point.
Havar is difficult to machine, as it undergoes rapid work hardening under the cutting tool. The tool should be as sharp as possible and the machine should be rigid, with minimal backlash. Higher power is required than to machine ordinary steels of similar hardness.
