Exera® High-N is a molybdenum and nitrogen alloyed austenitic stainless steel, used for orthopedic implants and fracture fixation devices.
The grade is characterized by:
- Proof strength is up to twice that of Exera® 316LVM in the annealed condition
- Higher corrosion resistance than Exera® 316LVM
- High microcleanliness
- Very good surface finish
- Good forgeability
Standards
-
UNS: S31675 -
BS: 7252-9
Product standard
- ASTM F1586
Chemical composition (nominal)
| C | Si | Mn | P | S | Cr | Ni | Mo | Cu | N | Nb |
|---|---|---|---|---|---|---|---|---|---|---|
| ≤0.06 | ≤0.60 | 4.0 | ≤0.025 | ≤0.003 | 20.5 | 9.5 | 2.4 | ≤0.20 | 0.4 | 0.3 |
Corrosion resistance
Exera® High-N has a very good resistance in physiological environments to:
- General and intergranular corrosion due to high purity and low ferrite content
- Pitting and crevice corrosion due to the high molybdenum content
Exera® High-N is capable of passing the Moneypenny Strauss corrosion test in accordance with ISO / ASTM requirements.
Forms of supply
Wire
Wire can be delivered in the following size ranges.
Spools/coils: diameter 0.1–6 mm
Drawn in straight lengths or ground straightened lengths: 0.6–6 mm
Tolerances
h8: ground finish as standard (tighter tolerances can be offered on request)
h9: drawn and straightened
Other product forms
This material can also be supplied as bar (round) and tube under the trademark Exera® High-N.
Mechanical properties
| Product | Condition | Tensile strength | Proof strength | Elongation A, | ||
|---|---|---|---|---|---|---|
| Rm | Rp0,2 | % | ||||
| MPa | ksi | MPa | ksi | |||
| min | min | min | min | typical | ||
| Wire | 1500 max | 217 max | ||||
| Bar | Annealed | 740 | 107 | 430 | 62 | 35 |
| Bar | Medium | 1000 | 145 | 700 | 102 | 20 |
| Bar | Hard | 1100 | 160 | 1000 | 145 | 10 |
| Tube, thick wall | Bright annealed | 740 | 107 | 430 | 62 | min 35 |
| Tube, thick wall | Cold finished | 1200 | 174 | 1100 | 160 | min 10 |
Specific tensile requirements available on request
Physical properties
| Property | ||
|---|---|---|
| Density ( 20 °C) | 8.0 g/cm3 | 0.29 lb/in3 |
| Modulus of elasticity, x103 (20°C) | 200 MPa | 29.0ksi |
| Specific heat capacity (20°C) | 485 J/(kg °C) | 0.11Btu/(lb°F) |
| Thermal conductivity (20°C) | 14W /(m°C) | 8 Btu/(ft h °F) |
| Thermal expansion, x10-6 (30-100°C) | 16.5 per °C | 9.5 per °F |
Machining
| Hardness | Cutting speed range | Feed range | |||
|---|---|---|---|---|---|
| SFM | m/min | IPR | mm/rev | ||
| Turning | 250-400 | 885-145 | 270-45 | 0.002-0.024 | 0.05-0.6 |
| Milling | 250-400 | 855-245 | 260-75 | 0.002-0.016 | 0.05-0.4 |
| Drilling | 250-400 | 115-195 | 35-60 | 0.002-0.012 | 0.05-0.3 |