Alloy Steel for Aerospace Applications

Alloy steel is carbon steel with additional elements such as nickel, chromium, molybdenum, and vanadium added to improve strength, toughness, hardenability, and fatigue resistance beyond what standard carbon steel can achieve. These enhanced properties make alloy steel the standard choice for aerospace, defense, and heavy industrial components subjected to extreme cyclic loading and high impact.

4130 is a chromium molybdenum alloy prized for its weldability and good strength, making it a common choice for aircraft fuselage structures, engine mounts, and welded airframe assemblies. 4340 adds nickel to the alloy composition, giving it significantly higher tensile strength and load bearing capacity, which is why it is specified for landing gear, flap tracks, and other highly loaded structural components rather than welded assemblies. 

Vacuum melt, also called vacuum arc remelt (VAR), is a secondary melting process that removes impurities and inclusions from the steel, resulting in improved purity, consistency, fatigue life, and fracture toughness compared to standard air melt material. Tailwind stocks 4330 and 4340 in both normalized and tempered as well as vacuum melt condition, certified to specifications like AMS 6414 for VAR material, so you can source the grade of purity your application requires.

300M is a modified version of 4340 with added silicon and vanadium, which further improve fatigue strength and fracture toughness. This makes 300M the preferred material for the most demanding airframe applications, including critical landing gear and highly loaded structural components where 4340 alone may not provide sufficient margin.

We stock alloy steel sheet and plate in 4130 and 4340, certified to AMS 6350, AMS 6345, and AMS 6359. Our alloy steel bar and rod inventory includes 4130, 4140, 4330 (normalized and tempered as well as vacuum melt), 4340 (normalized and tempered as well as vacuum melt), and 300M, certified to specifications including AMS 6370, AMS 6382, AMS 6411, AMS 6414, AMS 6415, AMS 6417, AMS 6419, AMS 6427, AMS 2300, AMS 2301, and AMS-S-6758.

Yes. Tailwind offers alloy steel cut to size along with value added processing to help streamline your production cycle and reduce extra steps on your end. Contact our team with your size, grade, and specification requirements for a custom quote.

Yes. In addition to our stocked inventory of 4130, 4140, 4330, 4340, and 300M, our team of industry veterans can source hard to find grades and specifications through our network of approved mill partners, so you're not stuck without material for programs with challenging requirements.