300M is a low alloy, vacuum melted, steel of very high strength and toughness. It is a modified 4340 steel with silicon, vanadium and slightly greater carbon and molybdenum content than 4340. 300M has a very good combination of strength, 280 to 305 ksi, with toughness, fatigue strength and good ductility. It is a through hardening alloy. Applications for 300M steel are those that require high strength such as aircraft landing gear, high strength bolts and airframe parts.
| Specification | Description |
|---|---|
| AMS 6257 | Steel Bars and Forgings. Vacuum Arc Re-Melted. Normalized and Tempered. |
| AMS 6417 | Steel Bars and Forgings. Vacuum Arc re- Melted . |
| AMS 6419 | Steel Bars and Forgings. Vacuum Arc Re-Melted. |
| BMS7-26 | Steel Bars and Forgings. Aircraft Quality. |
| DMS 1935 | Steel Bars. Vacuum Melted. |
| MIL-S-83135 | Steel Bars and Forgings. Aircraft Quality |
| MIL-S-8844 CL.3 | Steel Bars and Forgings. Aircraft Quality. |