Steel A48 Class 40
ASTM A48 Class 40 · EN EN-GJL-250, GG25 · JIS FC250 · GB HT250
ASTM A48 Class 40 is a flake-graphite gray cast iron at the higher-strength end of the A48 class series, also designated HT250, FC250, EN-GJL-250, GG25 and 0.6020.
Reference datasheet — A48 Class 40 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AC condition
A48 Class 40 tempers and conditions
A48 Class 40 is supplied in 6 conditions, soft to hard. AC is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Use when maximum machinability is needed and the strength drop from decomposing pearlite is acceptable. | 165 | 230 | 0.9 | 165 HB | 2.4 % IACS |
Class 40C | Heavy-section castings; slower cooling coarsens graphite so strength and hardness fall to the class minimum. | 213 | 278 | 0.7 | 17 HRC | 2.3 % IACS |
Stress relieved | Choose for dimensionally critical machined parts (machine bases, valve bodies) to remove casting residual stress with almost no loss of strength. | 220 | 285 | 0.6 | 230 HB | 2.2 % IACS |
ACDefault Spheroidize annealed | Standard commercial supply condition for sand castings of medium wall thickness. | 225 | 293 | 0.6 | 235 HB | — |
Full hard | Pick for wear surfaces — ways, cam faces, cylinder bores — where a hard martensitic skin over an unchanged gray-iron core is wanted. | 230 | 293 | 0.4 | 50 HRC | 2 % IACS |
Class 40A | Thin-section castings where faster cooling gives finer graphite and higher strength/hardness. | 240 | 310 | 0.5 | 23 HRC | 2.1 % IACS |
Supply forms, finishes and certifications
Ways A48 Class 40 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CC | Continuous Cast Bar | Surface finish |
What is A48 Class 40?
ASTM A48 Class 40 is a flake-graphite gray cast iron at the higher-strength end of the A48 class series, also designated HT250, FC250, EN-GJL-250, GG25 and 0.6020. Engineers specify it for sand-cast housings, frames and bar stock where 293 MPa tensile strength, 225 MPa yield, 235 HB hardness, high damping and good sliding wear resistance matter more than ductility, with service to 400 °C. Elongation is only 0.6 % and the elastic modulus is 125 GPa, so the material is brittle under shock and is repair-weldable only. Where impact toughness or weldable structure is required, move to ductile iron such as A536 60-40-18 or 80-55-06. A48 Class 40 has a density of 7.15 g/cm³ (0.258 lb/in³), lighter than 99% of steel grades. It melts at 1,150°C (2,102 °F). A48 Class 40 has a yield strength of 225 MPa (32.6 ksi) and a tensile strength of 293 MPa (42.5 ksi) — weaker than 97% of steel grades. Elongation at break is 0.6% and the elastic modulus is 125 GPa (18.1 Msi).
What is A48 Class 40 used for?
- cylinder blocks
- gearbox housings
- brake drums
- machine frames
Advantages
- Low embodied carbon — 1.7 kg CO₂/kg, better than 99% of steel grades
- Easy to machine — 65/100, better than 93% of steel grades
Limitations
- Low stiffness — 125 GPa (18.1 Msi), worse than 99% of steel grades
- Limited ductility — 0.6%, worse than 99% of steel grades
- Low fracture toughness — 16 MPa·√m (14.6 ksi·√in), worse than 99% of steel grades
- Limited formability — 3/100, worse than 99% of steel grades
- Hard to polish — 35/100, worse than 99% of steel grades
A48 Class 40 properties
Typical room-temperature values for A48 Class 40-AC; bars are the position among steel grades.
Physical3
A48 Class 40 has a density of 7.15 g/cm³ (0.258 lb/in³), lighter than 99% of steel grades. It melts at 1,150°C (2,102 °F).
Mechanical14
A48 Class 40 has a yield strength of 225 MPa (32.6 ksi) and a tensile strength of 293 MPa (42.5 ksi) — weaker than 97% of steel grades. Elongation at break is 0.6% and the elastic modulus is 125 GPa (18.1 Msi).
Thermal6
A48 Class 40 is rated for continuous service to 400°C (752 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
A48 Class 40 conducts electricity at 2.2 % IACS, worse than 98% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of A48 Class 40 takes about 18 MJ of energy and emits 1.7 kg of CO₂ — less than 100% of steel grades. Typical recycled content is 90%.
Manufacturability8
A48 Class 40's machinability is good (65/100, better than 93% of steel grades); weldability poor (20/100); formability not recommended (3/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. A48 Class 40 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A48 Class 40
Is A48 Class 40 easy to machine?
Machines easily and gives short broken chips — run dry or with air blast, use carbide (K10/K20) or CBN at high speed; expect abrasive wear from casting skin and hard edges, so break through the skin on the first cut.
Can A48 Class 40 be welded?
Poor weldability: repair only, using nickel or NiFe electrodes with 300–500 °C preheat, short stringer beads with peening, and slow cool to avoid white-iron/crack-prone HAZ.
Can A48 Class 40 be formed, bent or molded?
Not formable — shape is fixed in the mould; excellent green-sand/shell fluidity, low shrinkage (~1%) and good feeding, but control section transitions and cooling rate to keep hardness and strength uniform.
A48 Class 40 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Ctotal carbon; ASTM A48 does not fix composition — typical foundry practice for Class 40 / HT250 | 2.9 – 3.4 | 3.2 |
| Si | 1.6 – 2.3 | 1.9 |
| Mnpearlite stabilizer | 0.6 – 1 | 0.8 |
| P | ≤ 0.15 | 0.08 |
| S | ≤ 0.12 | 0.08 |
| Croptional, to raise strength/hardness in heavy sections | 0 – 0.35 | 0.2 |
| Cuoptional pearlite promoter | 0 – 0.6 | 0.2 |
| Fe | balance | — |
What surface finishes work on A48 Class 40?
Shot-blast then prime/paint or phosphate for corrosion protection; can be flame/induction hardened or nitrided for wear; not anodizable and graphite flakes limit polished or chrome-plated finishes.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel A48 Class 40 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- EN-GJL-250GG250.6020
- GB (China)
- HT250
- JIS
- FC250
How much does A48 Class 40 cost?
A48 Class 40 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
A48 Class 40 — frequently asked
What is A48 Class 40 used for?
A48 Class 40 is typically used for cylinder blocks, gearbox housings, brake drums and machine frames. In short: higher-strength gray iron class; excellent vibration damping; free-machining ferrous casting.
What is the yield strength of A48 Class 40?
A48 Class 40 has a typical yield strength of 225 MPa (32.6 ksi) and a tensile strength of 293 MPa (42.5 ksi) — weaker than 97% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is A48 Class 40 easy to machine?
Reasonably — machinability is rated good (65/100, better than 93% of steel grades). Machines easily and gives short broken chips — run dry or with air blast, use carbide (K10/K20) or CBN at high speed; expect abrasive wear from casting skin and hard edges, so break through the skin on the first cut.
Can A48 Class 40 be welded?
Not readily — weldability is rated poor (20/100). Poor weldability: repair only, using nickel or NiFe electrodes with 300–500 °C preheat, short stringer beads with peening, and slow cool to avoid white-iron/crack-prone HAZ.
What surface finishes work on A48 Class 40?
Shot-blast then prime/paint or phosphate for corrosion protection; can be flame/induction hardened or nitrided for wear; not anodizable and graphite flakes limit polished or chrome-plated finishes.
Can A48 Class 40 be formed, bent or molded?
Not formable — shape is fixed in the mould; excellent green-sand/shell fluidity, low shrinkage (~1%) and good feeding, but control section transitions and cooling rate to keep hardness and strength uniform.
What is the maximum service temperature of A48 Class 40?
A48 Class 40 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A48 Class 40-AC and A48 Class 40-ANN?
AC is the default condition — standard commercial supply condition for sand castings of medium wall thickness. ANN: use when maximum machinability is needed and the strength drop from decomposing pearlite is acceptable. Yield strength is 225 MPa in AC versus 165 MPa in ANN.
How much does A48 Class 40 cost?
A48 Class 40 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A48/A48M — Standard Specification for Gray Iron Castings — ASTM International (2022)
- GB/T 9439 (HT250) — SAC (2010)
- EN 1561 Founding — Grey cast irons (EN-GJL-250) — CEN (2011)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.15 — Casting — ASM International (2008)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
- Continuous cast gray iron bar stock datasheets (Class 40 grade) — bar-stock producers (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.