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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 20 is a high-carbon, flake-graphite gray cast iron exhibiting superior vibration damping capacity, high thermal conductivity, and outstanding machinability. It possesses a predominantly ferritic-pearlitic matrix structure with coarse Type A graphite flakes, making it ideal for non-structural housings, counterweights, and components where thermal dissipation and ease of casting outweigh tensile requirements.
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 20 | 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 | F11401 | 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 G2000 | 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 20 Gray Iron | Commercial Alias | Colloquial or commercial industry synonym |
| Gray Iron 20 | Colloquial Alias | Colloquial or commercial industry synonym |
| SAE G2000 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 G2000) | 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 | 3.40 – 3.80 | wt% | Total carbon content controls graphite flake formation and eutectic degree.Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Silicon | Si | 0 | RANGE | 2.30 – 2.80 | wt% | Graphitizing element promoting ferrite and coarse flake formation.Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Manganese | Mn | 0 | RANGE | 0.50 – 0.80 | wt% | Ties up sulfur as manganese sulfide (MnS) inclusions.Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Phosphorus | P | 0 | MAXIMUM | ≤ 0.20 | wt% | Residual element; higher levels form brittle steadite eutectoid.Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Sulfur | S | 0 | MAXIMUM | ≤ 0.15 | wt% | Balanced against manganese content: Mn >= 1.7*S + 0.15.Ref: ASTM International, CEN, ISO & ASM International Standards Technical Committees | VERIFIED |
| Iron | Fe | 0 | REMAINDER | Remainder | wt% | Base metallic matrix element.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 | 7.1 g/cm³ | TYPICAL | 7.1 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 | 53 W/(m·K) | TYPICAL | Test Temp: 20 °C | 53 W/(m·K) | ASTM International, CEN & ISO Technical Committees | VERIFIED |
| Specific Heat Capacity | 460 J/(kg·K) | TYPICAL | Test Temp: 20 °C | 460 J/(kg·K) | ASTM International, CEN & ISO Technical Committees | VERIFIED |
| Coefficient of Thermal Expansion | 11.5 µm/(m·K) | TYPICAL | Mean CTE across 20°C to 100°C range. | 11.5 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 | 750 nΩ·m | TYPICAL | Test Temp: 20 °C | 750 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: ≥ 138 MPa (MINIMUM)Governing minimum tensile strength per ASTM A48 Class 20 (20 ksi = 138 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 (1.2 in.) diameter Test Bar B | ≥ 138 MPa | — | — | — | — | — | VERIFIED |
| Standard Product Form | As-CastSource values and qualifiersModulus of Elasticity: 80 GPa (TYPICAL)Secant modulus at 25% ultimate tensile stress. Lower than steel due to graphite flake disruption.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 | — | — | — | — | — | — | — | VERIFIED |
| Standard Product Form | As-CastSource values and qualifiersHBW Hardness: 130–180 HBW (RANGE)Brinell hardness measured with 10 mm tungsten carbide ball and 3000 kgf load per ASTM E10.10/3000ASTM 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 | — | — | — | — | — | — | 130–180 HBW | VERIFIED |
Machining, joining, forming, and thermal processing ratings cataloged from the cited authoritative technical reference.
Outstanding machinability rating (~110% relative to C36000 free-cutting brass baseline). The coarse graphite flakes disrupt the ferritic matrix, acting as continuous internal chip breakers and providing innate solid lubrication to cutting edges with negligible tool wear.
Poor weldability. Welding is generally restricted to non-structural repair casting salvaging. Requires minimum 250°C to 300°C preheating, high-nickel filler rods (AWS ENi-CI), light peening to mitigate shrinkage stress, and slow furnace cooling to avoid brittle white iron and martensitic heat-affected zones (HAZ).
Stress relief annealing at 540°C to 565°C (1000°F to 1050°F) for 1 hour per 25 mm of thickness relieves residual foundry stresses without softening. Graphitization annealing at 760°C converts residual pearlite to ferrite for maximum machinability.
Non-deformable. Cast iron lacks plastic ductility and cannot be cold or hot rolled, bent, forged, or stamped. All geometric shaping must occur in the mold cavity or through machining.
Comparable Grades & Cross-References: Carefully classified cross-reference relationships for ASTM A48 Class 20 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 20 provides higher thermal conductivity (53 vs 48 W/(m·K)) and superior vibration damping due to coarser graphite, but Class 30 provides 50% higher minimum tensile strength (207 vs 138 MPa) and higher wear resistance.Materials serve different design priorities (e.g. higher strength vs superior corrosion resistance or cost). | VERIFIED | Side-by-Side Compare → |
| EN-GJL-150 Gray Cast Iron | Cast Iron | Approximate Equivalent | EN-GJL-150 (min 150 MPa tensile on 15–30 mm wall) occupies similar low-strength, high-damping engineering territory to ASTM A48 Class 20 (min 138 MPa on 30.5 mm Test Bar B), but test bar geometries and section-sensitivity classifications differ.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 20 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).