AMS Specification Hy-Tuf Alloy Steel

AMS 6418

Hy-Tuf Wrought Low Alloy Steel – Bars, Forgings, Tubing & Rings

Steel, Bars, Forgings, Tubing, and Rings – 1.3Mn 1.5Si 0.30Cr 1.8Ni 0.40Mo (0.23-0.28C)

AS9100D / ISO 9001

Mill Test Reports

2–4 Week Delivery

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Quick Specification Facts

Spec Number AMS 6418 (AMS6418)

Material Hy-Tuf Wrought Low Alloy Steel

Spec Type AMS (Aerospace Material Specification)

Category Alloy Steel / Hy-Tuf

Composition 1.3Mn 1.5Si 0.30Cr 1.8Ni 0.40Mo (0.23-0.28C)

Condition Normalized, Annealed, or Quenched and Tempered per specification requirements

Product Forms Bars, Forgings, Tubing, and Rings

Melt Practice Air or Vacuum Melted

Certification AS9100D / ISO 9001 with full MTR traceability

Specification Overview

AMS 6418 (also referenced as AMS6418) covers Hy-Tuf, a wrought low-alloy steel, in the form of bars, forgings, tubing, and rings. This specification is issued by SAE International and is widely used in aerospace, defense, and high-strength structural applications requiring an exceptional combination of high tensile strength, toughness, and impact resistance. Hy-Tuf's nominal composition of 1.3% Manganese, 1.5% Silicon, 0.30% Chromium, 1.8% Nickel, 0.40% Molybdenum, and 0.23–0.28% Carbon delivers outstanding strength-to-weight ratio performance that is critical for weight-sensitive aerospace structural components.

AMS 6418 material is produced by air or vacuum melting to ensure consistent chemical composition and microstructural uniformity. The silicon content of 1.5% is notably higher than most alloy steels, which contributes significantly to the alloy's solid-solution strengthening and deoxidation. The combination of nickel for toughness, molybdenum for hardenability and temper embrittlement resistance, and chromium for added hardenability makes Hy-Tuf one of the premier high-strength low-alloy steels for demanding aerospace structural forgings, bars, tubing, and rings where both ultimate strength and fracture toughness are paramount.

Available Product Forms

Bars

Forgings

Tubing

Rings

AMS 6418 material is supplied as Bars, Forgings, Tubing, and Rings per specification requirements. Round bar, hex bar, forged billet, seamless tubing, and rolled ring forms are available in a range of diameters and cross-sections. Custom forgings, near-net-shape forgings, and machined blanks are available upon request. Contact our materials specialists for non-standard dimensions or custom forging and ring rolling requirements.

Nominal Chemical Composition

Element	Symbol	Nominal %	Notes
Iron	Fe	Balance	Base metal – provides structural matrix
Carbon	C	0.23–0.28%	Primary strengthening element; controls hardness and strength
Manganese	Mn	1.3%	Hardenability; solid-solution strengthener; deoxidizer
Silicon	Si	1.5%	Solid-solution strengthener; deoxidizer; improves strength and hardness
Chromium	Cr	0.30%	Hardenability; wear resistance; mild corrosion resistance
Nickel	Ni	1.8%	Toughness; hardenability; improves low-temperature impact properties
Molybdenum	Mo	0.40%	Hardenability; prevents temper embrittlement; improves high-temperature strength

Chemical composition ranges are nominal. Consult the current issue of AMS 6418 for precise minimum/maximum requirements. Aero-Vac provides full mill test reports (MTRs) with certified chemistry for every order.

Key Properties & Specification Details

Property / Attribute	Details
Specification Number	AMS 6418 (AMS6418)
Issuing Organization	SAE International (Society of Automotive Engineers)
Material Type	Low Alloy Steel – High Strength Bars, Forgings, Tubing, and Rings
Alloy Name	Hy-Tuf (Wrought Low Alloy Steel)
Nominal Composition	1.3Mn 1.5Si 0.30Cr 1.8Ni 0.40Mo (0.23-0.28C)
Melt Practice	Air or Vacuum Melted
Heat Treatment Condition	Normalized, Annealed, or Quenched and Tempered per specification requirements
Available Forms	Bars, Forgings, Tubing, and Rings
Tensile Strength	Very High – typically 220–260 ksi in the quenched and tempered condition
Fracture Toughness	Very Good – superior toughness compared to many high-strength steels at equivalent strength levels
Machinability	Good in annealed condition; more challenging in hardened condition; sharp tooling recommended
Weldability	Fair – requires pre- and post-weld heat treatment; low hydrogen electrodes recommended
Magnetic Properties	Magnetic (ferritic/martensitic)
Certification Available	AS9100D / ISO 9001, Certificate of Conformance, MTR

Typical Applications

Aerospace Structural Components: Airframe fittings, wing attach fittings, fuselage structural members, and high-strength brackets requiring an excellent combination of tensile strength, fracture toughness, and low weight penalty.

Landing Gear Components: Landing gear struts, actuator components, drag braces, and structural forgings for aircraft landing systems where ultra-high strength and impact resistance are critical safety requirements.

High-Strength Fasteners & Structural Hardware: Aerospace-grade bolts, pins, shafts, and structural fasteners for applications requiring very high tensile and shear strength with reliable toughness under dynamic loading.

Defense & Military Applications: Weapons system components, armored vehicle hardware, missile structural parts, and defense system forgings requiring consistent ultra-high-strength performance in demanding operational environments.

Aerospace Tooling & Fixtures: High-strength aerospace manufacturing tooling, jigs, fixtures, and precision mechanical components where dimensional stability, high strength, and good machinability in the annealed condition are required.

Frequently Asked Questions – AMS 6418

What is AMS 6418 and what does it cover?

AMS 6418 (also written AMS6418) is an SAE International aerospace material specification covering Hy-Tuf, a wrought low-alloy steel, in the form of bars, forgings, tubing, and rings. The nominal chemistry of 1.3Mn 1.5Si 0.30Cr 1.8Ni 0.40Mo (0.23-0.28C) delivers an exceptional combination of ultra-high tensile strength, fracture toughness, and impact resistance. The material is produced by air or vacuum melting and can be supplied in the normalized, annealed, or quenched and tempered condition per specification requirements. It is widely used in aerospace structural components, landing gear, defense hardware, and other applications where high strength-to-weight ratio and reliable toughness are critical.

What is Hy-Tuf steel and what makes it unique?

Hy-Tuf is a medium-carbon, low-alloy steel developed specifically for aerospace structural applications requiring ultra-high strength combined with excellent fracture toughness. Its distinctively high silicon content of 1.5% – significantly higher than most alloy steels – is the defining characteristic of the alloy, contributing to solid-solution strengthening and helping achieve high strength levels at lower carbon content than many competing alloys. The nickel addition improves toughness and low-temperature impact properties, while molybdenum enhances hardenability and resistance to temper embrittlement. The combination of these alloying elements allows Hy-Tuf to achieve tensile strengths in the 220–260 ksi range with superior fracture toughness compared to many steels at equivalent strength levels, making it a preferred choice for weight-critical aerospace structural forgings and machined components.

Does Aero-Vac supply AMS 6418 with full mill test reports and certifications?

Yes. All AMS 6418 material supplied by Aero-Vac is fully traceable to mill test reports (MTRs) confirming chemical composition and mechanical properties per the specification. We are AS9100D/ISO 9001 certified with a 99.6% quality rating. Every order ships with certificates of conformance, material certifications, and chemical/mechanical test reports. Electronic delivery of all documentation is available for fast turnaround. If your program requires additional special process certifications, our quality team can coordinate as needed.

What sizes of AMS 6418 bars, forgings, tubing, and rings does Aero-Vac stock?

Aero-Vac maintains inventory of AMS 6418 Hy-Tuf in round bar, forging, tubing, and ring forms across a range of diameters and sizes. We carry standard bar diameters and can provide custom-cut lengths from our in-house processing facility at the Port of Kalama. For custom forgings, rolled rings, or near-net-shape requirements, our team can source from our global supplier network. Contact us with your specific size and quantity requirements and we will provide a prompt quote with availability and lead time.

What are the typical lead times for AMS 6418 material?

In-stock AMS 6418 material is typically available for same-day or next-day shipment. For custom-cut or specially processed orders, our standard lead time is 2–4 weeks—significantly faster than the industry average of 8–12 weeks. Specialty forgings, rings, or items requiring mill production may require 4–8 weeks depending on quantity and dimensions. We prioritize urgent aerospace and defense requirements and will always provide honest, upfront delivery estimates. Rush processing is available on select items.

Can Aero-Vac provide value-added processing for AMS 6418 Hy-Tuf material?

Yes. Aero-Vac operates a complete in-house processing facility at our Port of Kalama location. For AMS 6418 Hy-Tuf bars, forgings, tubing, and rings, we offer precision saw cutting, surface grinding, turning, milling, and heat treatment services. We also provide comprehensive mechanical and non-destructive testing services in-house. Hy-Tuf's high-strength characteristics require careful heat treatment and machining practices, and our experienced team is fully equipped to handle this demanding alloy steel. Having all capabilities under one roof allows for faster turnaround, tighter quality control, and reduced overall cost compared to using multiple vendors. Contact us to discuss your specific processing requirements.

Need AMS 6418 material or a custom quote?

Our alloy steel specialists can provide fast pricing, availability, and technical guidance for your AMS 6418 Hy-Tuf requirements.