ASTM A48 Class 40 Gray Iron: Hoch-Strength Flake Graphite
ASTM A48/A48M · Published: 2026-06-02 · Updated: July 2026
ASTM A48 Class 40 is a high-strength gray cast iron with 276 MPa minimum tensile strength, achieved through a predominantly pearlitic matrix with Type A (random) flake graphite of controlled size (ASTM A247 Size 4-6). The higher strength compared...
ASTM A48 Class 40 ist ein hoch-strength gray cast iron mit 276 MPa minimum tensile strength, achieved durch ein predominantly pearlitic matrix mit Typ EIN (random) flake graphite von controlled size (ASTM A247 Size 4-6). Der higher strength compared zu Class 30 (50% increase) enables thinner casting wall sections und higher load-bearing capacity. Used für heavy-duty machine werkzeug beds (lathes, milling machines), large diesel motor blocks, compressor cylinders, und drücken frames wo vibration damping und hoch compressive strength sind kritisch. Requires inoculation practice während foundry processing zu ensure Typ EIN graphite formation und avoid chill (iron carbide) in thin sections. Abschnitt sensitivity ist higher als Class 30—thinner sections produce harder, stronger material; thicker sections require alloying additions (Cr, Cu) zu meet Class 40 minimums throughout.
Quick Facts
| Kategorie | Cast Iron |
| Norm | ASTM A48/A48M |
| Density | 7.25 g/cm³ |
| Yield Strength | N/A (brittle) |
| Tensile Strength | 276 MPa (40 ksi) |
Global Equivalents & Cross-Reference
| Alternative Standard / Grade | Action |
|---|---|
| EN-GJL-300 | Compare |
| GG25 | Compare |
| FC300 | Compare |
| HT300 | Compare |
| ISO 185/JL/300 | Compare |
Verwandt Materials
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Frequently Asked Questions
Ist Class 40 gray iron machinable mit carbide tooling?
Ja, though slower als Class 30. Der higher pearlite content (95%+) und finer graphite flakes produce harder material (200-240 HB) das requires reduced cutting speeds—approximately 80% von Class 30 speeds für turning, 70% für milling. Verwenden C-2 carbide grade mit generous positive rake angles. Der graphite noch provides chip-breaking und lubricating benefits, so werkzeug life remains gut despite higher hardness. Hard spots (chill) bei casting edges sollte sein removed durch grinding vor machining.
References & International Standards
- ASTM International. Norm Specifications für Stahl & Metal Alloys. astm.org
- International Organization für Standardization (ISO). Metallic Materials — Cross-Referenz Database. iso.org
- American Iron und Stahl Institute (AISI). Stahl Güte Designations & Equivalents. steel.org
- European Committee für Standardization (CEN). EN Stahl Standards & Numbering System. cencenelec.eu