Steel A842 Grade 300
ASTM A842 Grade 300 · EN EN-GJV-300 · GB RuT300
ASTM A842 Grade 300 is the lower-strength compacted graphite iron (CGI), matching EN-GJV-300 and RuT300, in which Mg-treated vermicular graphite gives grey-iron-like thermal conductivity and damping together with higher strength and stiffness.
Reference datasheet — A842 Grade 300 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 AS-CAST condition
A842 Grade 300 tempers and conditions
A842 Grade 300 is supplied in 4 conditions, soft to hard. AS-CAST is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick when maximum thermal conductivity, ductility and easy machining matter more than strength (exhaust manifolds, thermally cycled parts). | 215 | 310 | 4 | 150 HB | 3.1 % IACS |
Stress relieved | Standard treatment for dimensionally critical machined castings (blocks, heads, moulds) — removes casting residual stress with minimal property change. | 225 | 320 | 2.5 | 165 HB | 2.9 % IACS |
AS-CASTDefault ferritic/pearlitic compacted graphite iron | Standard supply condition: meets A842 Grade 300 straight from the mould with a mixed matrix, best balance of strength and thermal conductivity. | 230 | 330 | 2.5 | 170 HB | 36 W/m·K |
Normalized | Use when a Grade 300 casting must be lifted toward Grade 350/400 strength and wear resistance, accepting lower conductivity and worse machinability. | 295 | 400 | 1.5 | 20 HRC | 2.7 % IACS |
What is A842 Grade 300?
ASTM A842 Grade 300 is the lower-strength compacted graphite iron (CGI), matching EN-GJV-300 and RuT300, in which Mg-treated vermicular graphite gives grey-iron-like thermal conductivity and damping together with higher strength and stiffness. It is supplied as-cast, annealed, normalized or stress-relieved for castings that see thermal cycling: 230 MPa yield, 330 MPa tensile, 2.5 % elongation, 170 HB, 145 GPa modulus, 36 W/m·K and service to 400 °C. The compacted graphite window is narrow, so melt control is critical; machinability is poor (score 40) and fusion weldability is poor. Grey iron is cheaper and easier to cut where strength allows. A842 Grade 300 has a density of 7.1 g/cm³ (0.257 lb/in³), lighter than 99% of steel grades. It melts at 1,150°C (2,102 °F). A842 Grade 300 has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 330 MPa (47.9 ksi) — weaker than 97% of steel grades. Elongation at break is 2.5% and the elastic modulus is 145 GPa (21 Msi).
What is A842 Grade 300 used for?
- exhaust manifolds
- brake components
- housings
Advantages
- Low embodied carbon — 1.7 kg CO₂/kg, better than 99% of steel grades
Limitations
- Limited ductility — 2.5%, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Hard to polish — 35/100, worse than 99% of steel grades
- Low stiffness — 145 GPa (21 Msi), worse than 98% of steel grades
- Low strength — 230 MPa (33.4 ksi), worse than 97% of steel grades
A842 Grade 300 properties
Typical room-temperature values for A842 Grade 300-AS-CAST; bars are the position among steel grades.
Physical3
A842 Grade 300 has a density of 7.1 g/cm³ (0.257 lb/in³), lighter than 99% of steel grades. It melts at 1,150°C (2,102 °F).
Mechanical14
A842 Grade 300 has a yield strength of 230 MPa (33.4 ksi) and a tensile strength of 330 MPa (47.9 ksi) — weaker than 97% of steel grades. Elongation at break is 2.5% and the elastic modulus is 145 GPa (21 Msi).
Thermal6
A842 Grade 300 is rated for continuous service to 400°C (752 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical2
A842 Grade 300 has an electrical resistivity of 6×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of A842 Grade 300 takes about 19 MJ of energy and emits 1.7 kg of CO₂ — less than 100% of steel grades. Typical recycled content is 90%.
Manufacturability8
A842 Grade 300's machinability is fair (40/100, worse than 77% of steel grades); weldability poor (25/100); formability not recommended (5/100).
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. A842 Grade 300 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A842 Grade 300
Is A842 Grade 300 easy to machine?
Cuts harder than grey iron — no MnS lubricating layer, so use CBN/ceramic at moderate speed or coated carbide with rigid setups; keep residual Ti low and control nodularity to protect tool life.
Can A842 Grade 300 be welded?
Poor; repair only with Ni or NiFe electrodes, 300–400 °C preheat and slow cooling to avoid carbides and cracking in the HAZ.
Can A842 Grade 300 be formed, bent or molded?
Sand or shell moulded with in-mould/ladle Mg treatment plus process control (thermal analysis) — the compacted window is narrow, so over-treatment gives nodules and under-treatment flake graphite.
A842 Grade 300 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; A842 leaves chemistry to producer/purchaser agreement — values are typical CGI practice | 3.4 – 3.9 | 3.6 |
| Si | 1.9 – 2.6 | 2.3 |
| Mnhigher end promotes pearlite | 0.2 – 0.6 | 0.35 |
| Mgresidual; controls compacted vs nodular graphite | 0.01 – 0.02 | 0.01 |
| Tioptional anti-nodularizer; degrades machinability if high | 0 – 0.15 | 0.03 |
| Cupearlite stabilizer | 0 – 0.8 | 0.3 |
| S | ≤ 0.03 | 0.01 |
| P | ≤ 0.05 | 0.03 |
| Fe | balance | — |
What surface finishes work on A842 Grade 300?
Shot blast then paint, phosphate or oil; not anodizable. Graphite pull-out limits mirror polishing; sealed machined faces are needed for gasket sealing.
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 A842 Grade 300 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- EN-GJV-300
- GB (China)
- RuT300
How much does A842 Grade 300 cost?
A842 Grade 300 is a standard-cost steel ($$), cheaper than about 71% 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.
A842 Grade 300 — frequently asked
What is A842 Grade 300 used for?
A842 Grade 300 is typically used for exhaust manifolds, brake components and housings. In short: grey-iron conductivity, higher strength; thermal-cycling casting grade; between grey and ductile iron.
What is the yield strength of A842 Grade 300?
A842 Grade 300 has a typical yield strength of 230 MPa (33.4 ksi) and a tensile strength of 330 MPa (47.9 ksi) — weaker than 97% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A842 Grade 300 easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Cuts harder than grey iron — no MnS lubricating layer, so use CBN/ceramic at moderate speed or coated carbide with rigid setups; keep residual Ti low and control nodularity to protect tool life.
Can A842 Grade 300 be welded?
Not readily — weldability is rated poor (25/100). Poor; repair only with Ni or NiFe electrodes, 300–400 °C preheat and slow cooling to avoid carbides and cracking in the HAZ.
What surface finishes work on A842 Grade 300?
Shot blast then paint, phosphate or oil; not anodizable. Graphite pull-out limits mirror polishing; sealed machined faces are needed for gasket sealing.
Can A842 Grade 300 be formed, bent or molded?
Sand or shell moulded with in-mould/ladle Mg treatment plus process control (thermal analysis) — the compacted window is narrow, so over-treatment gives nodules and under-treatment flake graphite.
What is the maximum service temperature of A842 Grade 300?
A842 Grade 300 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 A842 Grade 300 AS-CAST and A842 Grade 300 NORM?
AS-CAST is the default condition — standard supply condition: meets A842 Grade 300 straight from the mould with a mixed matrix, best balance of strength and thermal conductivity. NORM: use when a Grade 300 casting must be lifted toward Grade 350/400 strength and wear resistance, accepting lower conductivity and worse machinability. Yield strength is 230 MPa in AS-CAST versus 295 MPa in NORM.
How much does A842 Grade 300 cost?
A842 Grade 300 is a standard-cost steel ($$), cheaper than about 71% 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 A842 Standard Specification for Compacted Graphite Iron Castings — ASTM International (2020)
- EN 16079 Founding — Compacted (vermicular) graphite cast irons — CEN (2011)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys (Cast Irons) — ASM International (1990)
- SinterCast Compacted Graphite Iron material properties — SinterCast AB (2020)
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.