AMS 6345
AMS 6345 is the SAE Aerospace Material Specification for SAE 4130 chromium-molybdenum low-alloy steel in the sheet, strip, and plate product form. The specification covers material in the annealed, normalized, and normalized-and-tempered conditions in thicknesses from 0.010 inch to 3.000 inches and widths to 60 inches. AMS 6345 sets requirements for chemical composition (0.28–0.33% C, 0.80–1.10% Cr, 0.15–0.25% Mo), mechanical properties, grain size, and non-metallic inclusion content for aerospace-quality flat-rolled 4130 steel.
Sheet and plate to AMS 6345 are used extensively for aircraft fuselage skins, engine nacelle panels, structural brackets, and formed airframe fittings where the combination of moderate strength, excellent weldability, and low cost provides the optimal solution for mid-strength structural applications not requiring the ultra-high-strength grades.
In the normalized condition, AMS 6345 material develops a minimum tensile strength of 90,000 psi and minimum yield strength of 70,000 psi. In the quenched and tempered condition, tensile strengths of 125,000–150,000 psi are achievable in thin gauge. The 4130 composition provides full weldability by all standard aerospace welding processes (GTAW, GMAW, resistance welding) without preheat for thicknesses under 0.125 inch, making it the standard alloy for welded aircraft fuselage and airframe tube assemblies.
- Aircraft fuselage structural panels and skins
- Engine nacelle and cowling structural members
- Formed and welded airframe brackets and fittings
- Rocket motor case skins and forward/aft closures
- Motorsport and experimental aircraft structural panels
Certified Material for Critical Service
Material supplied to AMS 6345 must comply with chemical composition limits per the specification table, mechanical property requirements for the applicable condition, grain size requirements where specified, and inclusion ratings per AMS 2301. Certified mill test reports documenting heat chemistry and mechanical properties accompany each shipment. Full heat-lot traceability is maintained per AS9100 and NADCAP requirements.