SAE 4000 Series Alloy Steel
The SAE 4000 series alloy steel comprises chromium-molybdenum low-alloy steels (4130, 4140, 4150) characterized by excellent hardenability, high strength-to-weight ratio, and good toughness in the quenched and tempered condition. They are the workhorses of aerospace structural, landing gear, and defense applications.
4000 series alloy steels achieve tensile strengths from 95 ksi (normalized) to over 200 ksi (Q&T) depending on grade and heat treatment. They are weldable, machinable, and available in bar, forging, tube, and plate forms.
Product Forms of SAE 4000 Series
SAE 4000 alloy steel flat bar and plate is available in thicknesses from 0.250″ to 8.000″ in normalized or quenched and tempered condition for structural machining and tooling.
HEAT TREATMENT OF SAE 4000 SERIES
SAE 4000 series alloy steels are heat treated by austenitizing at 1550–1650°F, quenching in oil or water, and tempering at 400–1200°F to achieve the required strength level. Higher tempering temperatures reduce strength and increase toughness.
4150 Alloy Steel
4150 alloy steel — higher carbon Cr-Mo grade with maximum strength after quench and temper for aerospace precision components.
Certified Material for Critical Service
SAE 4000 series is supplied as certified material with full mill certifications, chemical analysis, mechanical test reports, and complete heat-lot traceability for aerospace and defense applications.