Home > Steel 300M

Home > Online Catalog > Steel > 300M View ASTM Numbers > View AMS Numbers >

300M is a low alloy, vacuum melted, steel of very high strength. Essentially it is a modified AISI 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), toughness, fatigue strength and good ductility. It is a through hardening alloy.

Applications for 300M steel are those that require strength in the 290 – 300 ksi range, such as aircraft landing gear, high strength bolts, flap tracks, structural applications and airframe parts.

Chemical Properties

Element	min	max
Carbon	0.40	0.45
Manganese	0.60	0.90
Silicon	1.45	1.80
Phosphorus	—	0.010
Sulfur	—	0.010
Chromium	0.70	0.95
Nickel	1.65	2.00
Molybdenum	0.30	0.50
Vanadium	0.05	0.10
Copper	—	0.35

Minimum Longitudinal Tensile Properties

Property	Value
Tensile Strength	280 ksi
Yield Strength at 0.2% Offset	230 ksi
Elongation in 4D	7%
Reduction of Area	25%

Minimum Transverse Tensile Properties, Inch/Pound Units

Nominal Cross-Sectional Area Square Inches	Tensile Strength ksi	Yield Strength at 0.2% Offset ksi	Average Reduction of Area %	Individual Reduction of Area %
Up to 100, incl	280	230	30	25
Over 100 to 144, incl	280	230	25	20
Over 144 to 225, incl	280	230	20	15
Over 225	280	230	15	10

Select AMS Number:

AMS Number	Alloy	Type	UNS	Cross Ref. Spec	Misc./Shape
AMS 6257	300M	Steel	-
AMS 6257 Bar	300M	Steel	-	-	Bar
AMS 6257 Forging	300M	Steel	-	-	Forging
AMS 6257 Tubing	300M	Steel	-	-	Tubing
AMS 6417	300M	Steel	-
AMS 6417 Bar	300M	Steel	-	-	Bar
AMS 6417 Forging	300M	Steel	-	-	Forging
AMS 6417 Tubing	300M	Steel	-	-	Tubing
AMS 6419	300M	Steel	K44220
AMS 6419 Bar	300M	Steel	K44220	MIL-S-8844	Bar
AMS 6419 Forging	300M	Steel	K44220	MIL-S-8844	Forging
AMS 6419 Plate	300M	Steel	K44220	MIL-S-8844	Plate
AMS 6419 Tubing	300M	Steel	K44220	MIL-S-8844	Tubing