Steel G3500
Grade · default condition
ASTM A48 Class 35B · EN EN-GJL-250 · JIS FC250 · GB HT250
Default stocked condition: higher-strength pearlitic gray iron for engine blocks, heads, brake components and machine-tool structures.
Values for the G3500 condition
Other G3500 tempers and conditions
G3500 is listed in 9 conditions; see the grade overview at G3500.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
as-cast ferritic-pearlitic gray iron, 187 HB max | Softest J431 grade — pick for maximum machinability and damping where strength is unimportant (covers, housings, low-stress brackets). | 100 | 140 | 0.6 | 175 HB | 53 W/m·K |
as-cast gray iron, 170–229 HB | General-purpose light-duty grade for small engine blocks, clutch plates, transmission cases and pressure-tight housings. | 130 | 190 | 0.5 | 200 HB | 50 W/m·K |
high-carbon (≥3.4 % C) gray iron, 170–229 HB, ≥70 % pearlite | Same hardness band as G2500 but high carbon and pearlitic matrix for brake drums and clutch parts that must resist heat checking. | 130 | 190 | 0.5 | 200 HB | 53 W/m·K |
as-cast gray iron, 187–241 HB | Workhorse grade for engine blocks, cylinder heads, flywheels and pump bodies needing moderate strength with easy machining. | 155 | 220 | 0.5 | 210 HB | 48 W/m·K |
very high carbon pearlitic gray iron, 207–255 HB, severe brake service | Highest-carbon J431 brake grade — maximum thermal conductivity and crack resistance for severe-duty brake drums and discs. | 172 | 245 | 0.5 | 225 HB | 53 W/m·K |
high-carbon pearlitic gray iron, 207–255 HB, heavy-duty brake service | Choose for truck/bus brake drums and heavy clutch plates: same hardness as G3500 but higher carbon for heat-check resistance and conductivity. | 175 | 250 | 0.5 | 225 HB | 50 W/m·K |
G3500DefaultThis page as-cast pearlitic gray iron, 207–255 HB | Default stocked condition: higher-strength pearlitic gray iron for engine blocks, heads, brake components and machine-tool structures. | 180 | 250 | 0.5 | 225 HB | 46 W/m·K |
as-cast pearlitic gray iron, 217–269 HB | Highest plain (unalloyed) strength grade — for heavily loaded engine blocks, heads, camshafts and hydraulic bodies where stiffness matters. | 205 | 290 | 0.4 | 22 HRC | 43 W/m·K |
alloyed pearlitic gray iron for diesel castings, 241–321 HB | Cr/Mo-alloyed, fully pearlitic and often heat treated — used for diesel cylinder heads and blocks needing hot strength and wear resistance. | 215 | 300 | 0.4 | 29 HRC | 40 W/m·K |
What is G3500?
G3500 is G3500 in the G3500 grade — default stocked condition: higher-strength pearlitic gray iron for engine blocks, heads, brake components and machine-tool structures. G3500 has a yield strength of 180 MPa (26.1 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 99% of steel grades. Elongation at break is 0.5% and the elastic modulus is 110 GPa (16 Msi). G3500 has a density of 7.2 g/cm³ (0.26 lb/in³), lighter than 99% of steel grades. It melts at 1,150°C (2,102 °F).
Advantages
- Easy to machine — 78/100, better than 97% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
Limitations
- Low stiffness — 110 GPa (16 Msi), worse than 100% of steel grades
- Limited ductility — 0.5%, worse than 100% of steel grades
- Low fracture toughness — 15 MPa·√m (13.7 ksi·√in), worse than 100% of steel grades
- Low strength — 180 MPa (26.1 ksi), worse than 99% of steel grades
- Limited formability — 3/100, worse than 99% of steel grades
G3500 properties
Typical room-temperature values for G3500; 18 are specific to this condition. Other listed values are G3500 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
G3500 has a density of 7.2 g/cm³ (0.26 lb/in³), lighter than 99% of steel grades. It melts at 1,150°C (2,102 °F).
Mechanical14
G3500 has a yield strength of 180 MPa (26.1 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 99% of steel grades. Elongation at break is 0.5% and the elastic modulus is 110 GPa (16 Msi).
Thermal6
G3500 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 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
G3500 conducts electricity at 2.2 % IACS, worse than 98% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of G3500 takes about 21 MJ of energy and emits 1.9 kg of CO₂ — less than 99% of steel grades. Typical recycled content is 85%.
Manufacturability8
G3500's machinability is very good (78/100, better than 97% of steel grades); weldability poor (25/100); formability not recommended (3/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with G3500
Is G3500 easy to machine?
Excellent dry machinability with carbide or CBN; flake graphite breaks chips, but hard cast skin and any chill/carbide areas demand rigid setups and depth of cut below the skin.
Can G3500 be welded?
Poor fusion weldability — repair only with NiFe/Ni electrodes, 300–400 °C preheat, short stringer beads and peening, or braze-weld to avoid martensite and cracking in the HAZ.
Can G3500 be formed, bent or molded?
Not cold formable; the grade is produced by green-sand or shell casting with excellent fluidity, low shrinkage and inoculation control to get A-type graphite and 207–255 HB as-cast.
What surface finishes work on G3500?
Shot blast then phosphate + paint or e-coat for corrosion protection; can be flame/induction hardened or nitrocarburized on wear faces; graphite flakes limit mirror polishing and plating adhesion.
G3500 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; SAE J431 leaves chemistry to the foundry except for the high-carbon brake grades (G2500a/G3500b/G3500c) and alloyed G4000d | 3.1 – 3.5 | 3.25 |
| Si | 1.8 – 2.4 | 2.1 |
| Mn | 0.5 – 0.9 | 0.7 |
| Plower P for pressure-tight castings | ≤ 0.15 | 0.08 |
| S | ≤ 0.15 | 0.1 |
| Cr0.25–0.45 % typical in alloyed G4000d for pearlite stabilisation | ≤ 0.45 | 0.15 |
| Cuoptional pearlite promoter | ≤ 0.6 | 0.2 |
| Mooptional, mainly G4000d | ≤ 0.35 | — |
| Nioptional | ≤ 0.5 | — |
| Fe | balance | — |
G3500 — frequently asked
What is G3500 used for?
G3500 is typically used for engine blocks, brake drums/rotors, cylinder liners and flywheels. In short: automotive-grade gray iron; stronger than Class 30; good conductivity and wear resistance.
What is the yield strength of G3500?
G3500 has a typical yield strength of 180 MPa (26.1 ksi) and a tensile strength of 250 MPa (36.3 ksi) — weaker than 99% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is G3500 easy to machine?
Yes — machinability is rated very good (78/100, better than 97% of steel grades). Excellent dry machinability with carbide or CBN; flake graphite breaks chips, but hard cast skin and any chill/carbide areas demand rigid setups and depth of cut below the skin.
Can G3500 be welded?
Not readily — weldability is rated poor (25/100). Poor fusion weldability — repair only with NiFe/Ni electrodes, 300–400 °C preheat, short stringer beads and peening, or braze-weld to avoid martensite and cracking in the HAZ.
What surface finishes work on G3500?
Shot blast then phosphate + paint or e-coat for corrosion protection; can be flame/induction hardened or nitrocarburized on wear faces; graphite flakes limit mirror polishing and plating adhesion.
Can G3500 be formed, bent or molded?
Not cold formable; the grade is produced by green-sand or shell casting with excellent fluidity, low shrinkage and inoculation control to get A-type graphite and 207–255 HB as-cast.
What is the maximum service temperature of G3500?
G3500 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 G3500 and G3500-G1800?
G3500 is the default condition — default stocked condition: higher-strength pearlitic gray iron for engine blocks, heads, brake components and machine-tool structures. G1800: softest J431 grade — pick for maximum machinability and damping where strength is unimportant (covers, housings, low-stress brackets). Yield strength is 180 MPa in G3500 versus 100 MPa in G1800.
Sources
- SAE J431 — Automotive Gray Iron Castings — SAE International (2021)
- ASTM A48/A48M — Standard Specification for Gray Iron Castings — ASTM International (2022)
- GB/T 9439 (2010)
- EN 1561 — Founding: Grey cast irons — 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)
- Continuous-cast gray iron bar property data (Class 35 / G2) — Dura-Bar (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.