
Alloy Steels
Alloys International is your #1 source for alloy steels. Backed by our global mill network, we offer commercially graded aircraft steel, military-grade steel, maraging steel, and custom products for specific applications, including aerospace steel alloys — with full certification included on every order.
Grades (25)
Key grades
4340 / 4340 VAR
UNS G43400W.Nr 1.6565
Vacuum arc remelted 4340 for the cleanest structure available in a through-hardening aircraft-quality steel. Landing gear, shafting and high-load structure.
40NiCrMo8-4
AMS 6414 · AMS 6415 · AMS 6454 · AMS 6417 · UNS G43400
300M
300M (4340 modified) is the benchmark ultra-high-strength landing gear steel, vacuum melted and stocked as bar and forging billet.
AMS 6257 · AMS 6419
135 Mod
NIT135 Mod, nitriding quality, vacuum melted. Supplied as bar and billet for gear, shaft and high-fatigue applications.
AMS 6472 · AMS 6470 · AMS 6471
Aermet 100
Aermet 100 combines ultra-high strength with exceptional fracture toughness and stress corrosion resistance. Stocked in bar and billet for critical airframe hardware.
AMS 6478 · AMS 6532
M-50
M50 bearing steel, vacuum melted, for high temperature aircraft engine bearings and races. Also supplied as M50 NiL for case carburized bearing components.
AMS 6490 · AMS 6491
4320
4320 carburizing grade for gears, pinions and bearing races where a hard case and tough core are required.
ASTM A322
4330 Mod
4330M (4330 modified), vacuum melted, for heavy section forgings and high-strength structure with good toughness at section size.
AMS 6411 · AMS 6427
4620
4620 carburizing steel for gears, shafts and pins, supplied in bar and billet.
AMS 6294
6150
W.Nr 1.8159
6150 chrome-vanadium spring and tooling steel with excellent fatigue strength, in bar, billet and wire.
51CrV4
AMS 6448 · AMS 6455 · AMS 6450
8740
8740 chrome-nickel-moly steel, widely called out for fasteners, fittings and machined hardware in the heat treated condition.
AMS 6322 · AMS 6323 · AMS 6324 · AMS 6325 · AMS 6327
Also stocked
Maraging 250
AMS 6512 · AMS 6520 · AMS 6501
Maraging 300
AMS 6514 · AMS 6521
Maraging 350
AMS 6515
H-11
W.Nr 1.2343
X37CrMoV5-1
AMS 6437 · AMS 6485 · AMS 6487 · AMS 6488
Pyrowear, Alloy 53
AMS 6308
D6AC
AMS 6439
M50 NiL
AMS 6278 · AMS 6393
52100 VAR
UNS G52986
AMS 6440 · AMS 6444 · UNS G52986
17-22A
AMS 6304
4037
AMS 6300
4130
W.Nr 1.7218
25CrMo4
AMS 6356
4140
W.Nr 1.7225
42CrMo4
AMS 6349 · AMS 6379 · AMS 6381 · AMS 6382 · AMS 6395
4150
ASTM A29
8630
AMS 6280 · AMS 6530 · AMS 6535 · AMS 6550 · AMS 6281
9310 / 9310 VAR
UNS G93106W.Nr 1.6657
14NiCrMo13-4
AMS 6265 · AMS 6260 · AMS 6267 · UNS G93106