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Representative source rows, qualified by their reported conditions. Inspect the tables below for all values, limits, and source notes.
ASTM A48 Class 40 is a high-strength, premium engineering gray cast iron. Featuring a minimum tensile strength of 40 ksi (276 MPa) on standard Test Bar B, it possesses a completely pearlitic microstructure with fine Type A graphite flakes. It is frequently inoculated or microalloyed with chromium, copper, or molybdenum to maintain uniform pearlite and prevent chilling in variable casting sections. Widely used for diesel engine cylinder heads, heavy gears, and hydraulic manifolds.
Source-backed commercial trade name and short designations cataloged in canonical data.
Standard Designations & Applicable Specifications — Semantically classified designations distinguishing primary standard identifiers, commercial trade names, and applicable specification references.
| System | Identifier | Standard System Name | Classification Notes & Provenance |
|---|---|---|---|
| ASTMPRIMARY | A48 Class 40 | ASTM International | —Ref: Standard Specifications for Gray and Ductile Cast Iron (ASTM A48/A48M, ASTM A536, EN 1561, EN 1563, ISO 185, ISO 1083, SAE J431, SAE J434, ASM Handbook Vol 1) |
| UNS | F12801 | Unified Numbering System | —Ref: Standard Specifications for Gray and Ductile Cast Iron (ASTM A48/A48M, ASTM A536, EN 1561, EN 1563, ISO 185, ISO 1083, SAE J431, SAE J434, ASM Handbook Vol 1) |
| SAE | J431 G4000 | SAE International | —Ref: Standard Specifications for Gray and Ductile Cast Iron (ASTM A48/A48M, ASTM A536, EN 1561, EN 1563, ISO 185, ISO 1083, SAE J431, SAE J434, ASM Handbook Vol 1) |
| Recognized Name / Alias | Classification | Technical Usage & Context |
|---|---|---|
| Class 40 Gray Iron | Commercial Alias | Colloquial or commercial industry synonym |
| SAE G4000 Gray Iron | Historical Alias | Colloquial or commercial industry synonym |
| Standards Body | Specification Code | Specification Title / Scope | Relationship Type |
|---|---|---|---|
| ASTM | ASTM A48 / A48M | Standard Specification for Gray Iron Castings | Specification Reference |
| SAE | SAE J431 | Automotive Gray Iron Castings (Grade G4000) | Specification Reference |
| ISO | ISO 185 | Grey cast irons — Classification | Specification Reference |
Chemical Composition (Weight %) — Elemental limits and values from the cited source. Preserves exact semantic limits (minimums, maximums, and ranges).
| Element | Symbol | Atomic No. | Semantic Basis | Specified Value | Unit | Metallurgical Notes & Qualification | Data Status |
|---|---|---|---|---|---|---|---|
| Carbon | C | 0 | RANGE | 2.90 – 3.20 | wt% | Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Silicon | Si | 0 | RANGE | 1.60 – 2.00 | wt% | Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Manganese | Mn | 0 | RANGE | 0.70 – 1.00 | wt% | Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Phosphorus | P | 0 | MAXIMUM | ≤ 0.08 | wt% | Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Sulfur | S | 0 | MAXIMUM | ≤ 0.12 | wt% | Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Iron | Fe | 0 | REMAINDER | Remainder | wt% | Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
Source-specific physical properties. Test temperatures are shown only where reported.
| Property Parameter | Canonical SI Value | Semantic Basis | Test Temperature / Context Range | Source Raw Reference | Source Reference | Status |
|---|---|---|---|---|---|---|
| Density | 7.25 g/cm³ | TYPICAL | 7.25 g/cm³ | ASTM International, CEN & ISO Technical Committees | VERIFIED |
Phase change temperatures, thermal conductivity, specific heat, mean coefficients of thermal expansion across standardized temperature ranges, and recommended thermal processing windows.
| Property Parameter | Canonical SI Value | Semantic Basis | Test Temperature / Context Range | Source Raw Reference | Source Reference | Status |
|---|---|---|---|---|---|---|
| Thermal Conductivity | 44 W/(m·K) | TYPICAL | 44 W/(m·K) | ASTM International, CEN & ISO Technical Committees | VERIFIED | |
| Specific Heat Capacity | 490 J/(kg·K) | TYPICAL | 490 J/(kg·K) | ASTM International, CEN & ISO Technical Committees | VERIFIED | |
| Coefficient of Thermal Expansion | 10.8 µm/(m·K) | TYPICAL | 10.8 µm/(m·K) | ASTM International, CEN & ISO Technical Committees | VERIFIED |
Electrical conductivity and resistivity in their reported units and conditions.
| Property Parameter | Canonical SI Value | Semantic Basis | Test Temperature / Context Range | Source Raw Reference | Source Reference | Status |
|---|---|---|---|---|---|---|
| Electrical Resistivity | 620 nΩ·m | TYPICAL | 620 nΩ·m | ASTM International, CEN & ISO Technical Committees | VERIFIED |
Contextual Mechanical Properties & Tempers: Engineering strength, ductility, and hardness values grouped by product form, temper, and section thickness. Mechanical properties are contextual and not isotropic averages.
| Product Form | Temper / Condition | Section Size | Tensile (UTS) | Yield Strength | Elongation | Shear Strength | Fatigue Strength | Hardness (Scales Preserved) | Status |
|---|---|---|---|---|---|---|---|---|---|
| Standard Product Form | As-CastSource values and qualifiersUltimate Tensile Strength: ≥ 276 MPa (MINIMUM)Governing minimum tensile strength per ASTM A48 Class 40 (40 ksi = 276 MPa). Gray iron exhibits no distinct yield point.ASTM International, CEN, ISO & ASM International Standards Technical Committees — ASTM A48, ASTM A536, EN 1561, EN 1563, ISO 185, ISO 1083, SAE J431, SAE J434, ASM Handbook Vol 1 | 30.5 mm Test Bar B | ≥ 276 MPa | — | — | — | — | — | VERIFIED |
| Standard Product Form | As-CastSource values and qualifiers | — | — | — | — | — | — | — | VERIFIED |
| Standard Product Form | As-CastSource values and qualifiers | — | — | — | — | — | — | 210–260 HBW | VERIFIED |
Machining, joining, forming, and thermal processing ratings cataloged from the cited authoritative technical reference.
Good machinability (~70% relative to C36000 baseline). Fully pearlitic matrix requires rigid machine tool setups, coated carbide tooling, and positive rake geometries.
Extremely difficult to weld. Fusion welding creates high susceptibility to cracking due to high carbon equivalent. Recommended strictly for casting salvage using qualified hot-box procedures (350°C–400°C preheat).
Stress relief at 565°C–620°C for 2 hours. Induction surface hardening achieves 54–58 HRC for heavy wear surfaces.
Non-deformable. Cannot be rolled or cold formed.
Comparable Grades & Cross-References: Carefully classified cross-reference relationships for ASTM A48 Class 40 Gray Cast Iron. Comparable does not mean equivalent.
| Related Material | Family | Relationship Classification | Metallurgical Notes & Differences | Status | Action |
|---|---|---|---|---|---|
| ASTM A48 Class 30 Gray Cast Iron | Cast Iron | Commonly Compared | Class 40 provides 33% higher minimum tensile strength (276 vs 207 MPa) and greater wear resistance, but Class 30 is easier to cast without chilled edges and offers higher thermal conductivity (48 vs 44 W/(m·K)).Materials serve different design priorities (e.g. higher strength vs superior corrosion resistance or cost). | VERIFIED | Side-by-Side Compare → |
| EN-GJL-250 Gray Cast Iron | Cast Iron | Approximate Equivalent | EN-GJL-250 (min 250 MPa tensile on 15–30 mm wall) provides similar structural duty to ASTM A48 Class 40 (min 276 MPa on 30.5 mm Test Bar B), but differing standard test specimen dimensions require careful engineering comparison.Engineering substitution review required. Design calculations must verify temper, formability, and corrosion limits before specifying as a direct replacement. | VERIFIED | Side-by-Side Compare → |
Contextual technical guides explaining degradation mechanisms, testing methodologies, and selection criteria relevant to ASTM A48 Class 40 Gray Cast Iron.
Cast iron is an indispensable alloy family renowned for superior vibration damping and castability, but its iron matrix and carbon microstructure make it susceptible to atmospheric rust. Restoring rusted cast iron requires understanding how mechanical and chemical methods interact with the underlying metal.
Sources & Provenance Trail: Authoritative reference publications, standards specifications, and data registers cited across this material record.
Authoritative foundry data harmonized across ASTM A48, ASTM A536, EN 1561, EN 1563, ISO 185, ISO 1083, SAE J431, SAE J434, and ASM International Handbook Volume 1 (Properties and Selection: Irons, Steels, and High-Performance Alloys).