AMS 6419
AMS 6419 is the premium-grade SAE Aerospace Material Specification for 300M alloy steel, covering vacuum arc remelted (VAR) bar and forging stock. The VAR processing requirement distinguishes AMS 6419 from the air-melted AMS 6257 grade: VAR produces a significantly cleaner melt with lower oxygen and sulfur content, reducing the density of oxide and sulfide inclusions that are the primary fatigue crack initiation sites in high-cycle fatigue and rolling contact applications. This cleanliness improvement directly extends the fatigue life of finished landing gear forgings relative to air-melt material at equivalent strength levels.
AMS 6419 is specified for the most critical landing gear forgings — those governing aircraft structural fatigue life under repeated landing load cycles — where the investment in VAR-quality material is justified by extended service life, reduced inspection intervals, or reduced weight through higher design allowables enabled by better-characterized, lower-scatter fatigue properties of the premium-grade material.
AMS 6419 meets the same minimum 280,000 psi UTS requirement as AMS 6257, with identical minimum elongation (8%) and reduction of area (30%). The key difference is the VAR processing requirement and more stringent cleanliness limits per AMS 2300 (versus AMS 2301 for air-melt). In high-cycle fatigue tests at equivalent stress levels, VAR 300M typically demonstrates 3–5× longer fatigue life than air-melt material, with significantly lower scatter in fatigue test results — both important factors in probabilistic damage-tolerant structural design.
- Primary landing gear main fitting forgings on commercial widebody aircraft
- Military fighter aircraft landing gear structural forgings
- High-cycle fatigue-critical landing gear components at maximum structural weight
- Carrier-based aircraft landing gear (extreme load cycling)
- Landing gear cylinders and trunnion forgings for maximum service life
Certified Material for Critical Service
AMS 6419 certifications include all requirements of AMS 6257, plus explicit VAR melt process documentation, cleanliness per AMS 2300 (most restrictive category), and often additional requirements including macro etch, forging grain flow documentation, and fatigue test sampling. All material must be fully traceable to the specific VAR heat and lot number. Procurement drawings for primary landing gear forgings typically reference AMS 6419 by name rather than the air-melt 6257 when VAR quality is mandatory.