List of Aerospace Steel Grades: 9 Essential Alloys and Their Uses

Why Are Aerospace Steel Grades Held to a Higher Standard?

Every aircraft is a balance between weight and strength, and steel still carries some of the heaviest loads on board. Landing gear, engine shafts, actuators and fasteners all depend on aerospace steel grades that can survive extreme stress, repeated fatigue cycles and sharp temperature swings. These are not ordinary construction steels. They are usually melted under vacuum, controlled tightly for chemistry and cleanliness, and delivered with full test records.

This list explains the most widely used grades, what makes each one different, and how buyers can source them with confidence. It is written for engineers, procurement managers and industrial buyers who need to match a grade to a part and a specification.

Key Takeaways

• Aerospace steels fall into three groups: low-alloy steels, precipitation-hardening stainless steels and ultra-high-strength steels.
• 4340 and 300M dominate landing gear, while 17-4 PH and 15-5 PH suit fittings and actuators.
• The grade name alone is not enough. Check the AMS specification, melting practice and heat treatment.
• Certified traceability matters as much as chemistry.

The Main Families of Aerospace Steel

Low-alloy steels such as 4130 and 4340 offer high strength at a sensible cost. Precipitation-hardening stainless steels add corrosion resistance. Ultra-high-strength grades like maraging steel push strength even further for the most critical parts.

List of Aerospace Steel Grades at a Glance

Low-Alloy Steels: 4130, 4340, 300M and 9310

4130 is the go-to grade for welded tubular structures because it joins easily and stays tough. 4340 goes further, and depending on heat treatment its tensile strength can range from roughly 860 to 1,980 MPa, as this 4340 steel reference shows.

300M takes the 4340 base and adds silicon, vanadium and extra molybdenum. It is vacuum melted and reaches tensile strengths near 2,000 MPa, which explains its long use in landing gear, according to this 300M alloy profile. 9310 is different: it is carburised, so gears get a hard surface and a tough core.

Precipitation-Hardening Stainless: 17-4 PH, 15-5 PH and 13-8Mo

17-4 PH contains about 17% chromium and 4% nickel, and it can be aged to high strength while resisting corrosion. 15-5 PH offers improved toughness across the grain, so it is preferred where loads act in more than one direction. 13-8Mo is chosen when fatigue life and toughness are the priority.

Ultra-High-Strength Steels: Maraging and AerMet 100

Maraging steels contain around 18% nickel and very little carbon, and they gain strength from ageing rather than quenching. This keeps distortion low. AerMet 100 pairs very high strength with strong fracture toughness, a combination valued in modern landing gear.

How to Choose Between Aerospace Steel Grades?

Start with the part, then work backwards to the specification:

• Strength versus toughness: the strongest grade is not always the safest if it cracks more easily
• Corrosion exposure: choose a stainless grade for exposed fittings
• Weldability: 4130 welds easily, while many ultra-high-strength steels do not
• Specification: examples include AMS 6417 for 300M, AMS 6414 for 4340 and AMS 5643 for 17-4 PH
• Melting practice: vacuum arc remelted material gives cleaner steel and better fatigue life

What to Look for in Aerospace Steel Grades Manufacturers?

Reliable aerospace steel grades manufacturers control the whole route, from melting and forging to heat treatment and testing. Ask about quality approvals such as AS9100 and about the melting method used, because vacuum remelting directly affects cleanliness.

Request mill test certificates showing chemistry and mechanical results for every heat. Ultrasonic testing reports and clear batch traceability are also standard for critical bars and forgings.

Working With Aerospace Steel Grades Suppliers?

Good aerospace steel grades suppliers act as an extension of your engineering team. They confirm that the grade, temper and AMS specification match your drawing, and they flag mismatches before material ships.

Compare lead times, cutting and processing services, and export documentation. Many buyers also source other aerospace metals from the same partner, such as aluminium alloy sheet or titanium fasteners, which simplifies purchasing and paperwork.

Why an Aerospace Steel Grades Stockist Saves Time?

Mill lead times can stretch for months, and maintenance programmes rarely wait. An aerospace steel grades stockist holds certified bar and plate in popular grades, so you can order small quantities, cut lengths or urgent replacement stock without a full mill run.

Always confirm that stocked material arrives with its original certification. A stockist that keeps heat-number traceability intact protects you during audits.

Conclusion

We looked at how aerospace steels divide into low-alloy, precipitation-hardening stainless and ultra-high-strength families, and reviewed nine key grades from 4130 to AerMet 100. We also covered how to choose a grade by strength, toughness, corrosion and weldability, and what to verify with manufacturers, suppliers and stockists, including certificates, melting practice and traceability.

FAQs

Q1. Which steel grade is best for aircraft landing gear?

4340 and its stronger relative 300M are the most common choices, with AerMet 100 used where extra fracture toughness is needed. The final pick depends on the design load and the governing specification.

Q2. What is the difference between 17-4 PH and 15-5 PH stainless steel?

Both are precipitation-hardening stainless steels with similar strength. 15-5 PH offers better toughness across the grain, which suits parts loaded in several directions.

Q3. Why is vacuum melted steel preferred for aerospace parts?

Vacuum melting and remelting remove impurities and gases, which improves cleanliness and fatigue life. That matters for parts that see millions of load cycles.

Need certified aerospace-grade metals for your next project? Share your grade, specification and quantity at sales@metroexport.in or visit metroexport.in.