General Information for Material Stellite 31 (X40)
| Material Group |
S - Superalloys (Heat resistant and Titanium) |
| Sub-Group |
Superalloy |
| Hardness |
43.0 HRC |
| Tensile Strength |
[N/mm^2] |
| Machinability Range |
6 |
MACHINABILITY OF STELLITE 31 (X40) MATERIAL
Stellite 31 (X40) is a cobalt-based heat resistant superalloy (HRSA) material with a machinability rating of 6% and hardness of 43 HRC.
Stellite 31 (X40) has 56% cobalt, 10% nickel and additional alloying elements per the table below.
Cobalt-based alloys excel in wear resistance and chemical stability in harsh and hot conditions. Therefore, they are mainly used in valves and fittings in an acidic environment and medical implants such as artificial hip joints. In this sub-group, the material standards also define the allowed hardness range, and hardness is a significant factor affecting the machinability (besides the chemical composition). Cobalt-based alloys are the most challenging to machine superalloy sub-group with a poor machinability rating.
Superalloys should be machined with a positive and sharp cutting edges. Geometries that are suitable for austenitic stainless steel will also work well on HRSA. However, quality manufacturers will have in their catalogs additional geometries that are specifically designed for these challenging materials.
SUMMARY:
For general turning of material Stellite 31 (X40) at stable conditions use a grade with a very hard substrate and thin PVD coating.
For general milling use a grade with a semi hard substrate and PVD coating.
For detailed carbide grades recommendations, check the table below.
Recommended cutting speed range for turning at stable conditions is 70 - 100 [SFM] / 20 - 30 [m/min].
Recommended cutting speed range for milling with stable clamping and short overhang is 50 - 70 [SFM] / 15 - 20 [m/min].
For detailed cutting speed recommendations, check the table below.
Equivalent International Designations for Material Stellite 31 (X40)
| Standard |
Name |
| SAE |
ASTM A567 |
| DIN |
CoCr25NiW |
| BS |
3146.2 |
| ANFOR |
KC20WN |
Chemical Composition for Material Stellite 31 (X40)
| Element |
Amount |
| Chromium (Cr) |
25% |
| Nickel (Ni) |
10% |
| Cobalt (Co) |
56.0% |
| Tungsten (W) |
7% |
| Carbon (C) |
0.3% |
Cutting Speeds Recomendations for Material Stellite 31 (X40)
| Application |
Vc (m/min) |
Vc (SFM) |
| Turning |
20-30 |
70-100 |
| Milling |
15-20 |
50-70 |
| Parting |
15-15 |
50-50 |
| Grooving |
50-50 |
70-80 |
| Drilling |
20-25 |
70-80 |
Important! The speed estimation is given for an ideal situation:
- Most suitable carbide grade
- Stable tool clamping
- Stable workpiece clamping
- Good quality raw material
- A short overhang of the cutting tool.
- Nominal hardness of the material.
- etc.
Recommended Carbide Grades for Material Stellite 31 (X40)
Grade for Milling (Indexable)
Recommended Insert Cutting Edge Geometry for Material Stellite 31 (X40)
| Honing Size |
0.02-0.05 mm / 0.001-0.002" |
| Rake Angle |
13° -18° |
| Land Angle |
Neutral |
| Land Width |
0.10-0.20 mm / 0.004-0.008" |
| Ground Insert |
Recommended |
