Stainless steels are poor conductors of heat, and the thermal conductivity of all types of stainless steel falls off with increasing alloy, see table below.
Austenitic steels have the lowest thermal conductivity, while ferritic and martensitic steels have better conductivity.
| Steel Grade |
Thermal conductivity at 400 °C (W/m, K) |
| Carbon steel |
35 |
| 420 |
26.5 |
| 444 |
26.5 |
| 304 |
20.0 |
| 316L |
18.5 |
| 2205 |
24.0 |
| 904L |
18.0 |
The low thermal conductivity means that, for a given machining operation, the cutting edge temperatures are higher in stainless steel than in carbon steel. This naturally imposes severe requirements on the high-temperature hardness of the cutting edge and on its ability to withstand high temperatures.