|
Min. % |
Max % |
| Carbon |
0.38 |
0.46 |
| Silicon |
1.45 |
1.80 |
| Manganese |
0.60 |
0.90 |
| Chromium |
0.70 |
0.95 |
| Molybdenum |
0.30 |
0.65 |
| Phosphorous |
0 |
0.01 |
| Sulphur |
0 |
0.01 |
| Nickel |
1.65 |
2.00 |
| Vanadium |
0.05 |
|
Mechanical Property Requirements for Steels in the Heat-Treated Condition for Turned,
Peeled |
| Mechanical Property Designation |
|
| Tensile Strength Mpa |
Min |
1931 |
| Max |
|
| 0.2% Proof Stress Mpa |
Min |
1586 |
Elongation on
5.65√S0 % |
Min |
7 |
| Izod Impact J |
Min |
|
| Charpy Impact J |
Min |
|
| Hardness Brinell HB |
Min |
|
| Max |
|
| Forming |
| Forming by conventional methods is good in the annealed condition. |
| Heat Treatment |
| Annealing |
| Anneal at 840oC and slow furnace cool at a rate of less than 10oC per hour down to 310C. From there it may be air cooled. |
| Hardening |
| 300M must be normalized at 960oC before hardening. After the normalizing treatment the alloy is hardened by heating to 870oC and oil quenched. |
| Nitriding |
|
| Normalizing |
| Heat to 880 oC - 920 oC, hold until temperature is uniform throughout the section, soak for 10 - 15 minutes and cool in still air. |
| Stress Relieving |
| 290oC |
| Tempering |
| temper at 310oC to give a nominal 55Rc |
| Notes on Heat Treatment |
|
| Machining |
| Perferably done in the normalised or normalised and tempered condition. Final machining to finished tolerances is done by grinding with care due to hardness of (RC55). Stress relieve at 290oC after finish grinding. |
| Welding |
| 300M can be welded. It must be pre and post heated because the alloy will air harden due to heat input from welding. Job must be re-normalised and tempered prior to final heat treatment. 300M can be joined by fusion methods or flash resistance welding. |
