Chemical Composition
| Grade Symbol |
UNS Number |
Alloy |
Elements |
Composition % |
| F21 |
K31545 |
chromium-molybdenum |
Carbon |
0.05 - 0.15 |
| Manganese |
0.30 - 0.60 |
| Phosphorus |
0.040 max |
| Sulfur |
0.040 max |
| Silicon |
0.50 max |
| Chromium |
2.7 - 3.3 |
| Molybdenum |
0.80 - 1.06 |
Mechanical Properties
| Property | Value |
|---|
| Tensile Strength, min, ksi [MPa] |
75 [515] |
| Yield Strength, min, ksi [MPa] |
45 [310] |
| Elongation in 2 in. [50mm] or 4D, min, % |
20 |
| Reduction or Area, min, % |
30 |
| Brinell Hardness Number, HBW |
156-207 |
Heat Treatment
After hot working, forgings shall be cooled to a temperature below 1000 °F [538 °C] prior to heat treating in accordance with the requirements.
