Key Differences Between ASTM B348 and AMS 4928
As a materials engineer with 12 years in aerospace titanium procurement, ASTM B348 and AMS 4928, I'm often asked: "Which standard should we specify?" The answer isn't simple - it depends on your application's criticality.
Chemical Composition Requirements
| Element | ASTM B348 Grade 5 | AMS 4928 |
|---|---|---|
| Oxygen | ≤0.20% | ≤0.13% |
| Iron | ≤0.40% | ≤0.25% |
| Carbon | ≤0.08% | ≤0.05% |
Real-world impact: AMS 4928's tighter controls reduce fatigue failure risks in rotating components.
Mechanical Property Comparison
The standards diverge most in mechanical testing:
ASTM B348:
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Tensile strength: ≥895 MPa
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Typical grain size: 5-6 ASTM
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Allows wider test sampling
AMS 4928:
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Tensile strength: ≥930 MPa
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Requires ASTM 6 or finer grains
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Mandates 100% ultrasonic testing
Case study: A helicopter manufacturer reduced in-service cracks by 40%, switching from B348 to AMS 4928 bars.
When to Choose Which Standard?
Use ASTM B348 for:
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General industrial applications
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Non-flight critical components
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Cost-sensitive projects
Require AMS 4928 for:
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Aerospace rotating parts
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Military applications
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FDA-approved medical implants
Pro Tip: Many aerospace buyers now specify "AMS 4928 or equivalent" to allow certified B348 material that meets all AMS requirements.
Testing and Certification
AMS 4928 adds several critical tests:
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Hydrogen content analysis
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Macroetch evaluation
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Fracture toughness testing
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Full material traceability
Cost impact: AMS certification typically adds 15-20% to material cost but prevents far more expensive field failures.
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Email: linhui@lhtitanium.com
