Steel A842 Grade 400
ASTM A842 Grade 400 · EN EN-GJV-400 · GB RuT400
ASTM A842 Grade 400 is a mid-strength compacted graphite iron (EN-GJV-400, RuT400) widely adopted for diesel cylinder blocks and heads that need high fatigue and thermal-fatigue strength in thin walls.
Reference datasheet — A842 Grade 400 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 F condition
A842 Grade 400 tempers and conditions
A842 Grade 400 is supplied in 5 conditions, soft to hard. F is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Heavy section 60 < t ≤ 200 mm | Use for heavy-walled machine-tool castings and large cylinder blocks; graphite coarsening in 60-200 mm sections cuts as-cast strength to 340 MPa tensile, so check designs against these body values. | 295 | 340 | 1.5 | 13 HRC | 3 % IACS |
Heavy section 30 < t ≤ 60 mm | Use these cast-body values for medium heavy walls of 30 < t ≤ 60 mm under EN 16079 grading; slower solidification lowers tensile strength to 390 MPa and hardness to 210 HB. | 320 | 390 | 1.5 | 15 HRC | 3.1 % IACS |
Stress relieved | Use stress relieving at 540–580 °C with slow cooling before finish machining of blocks and heads with uneven wall thickness; dimensional stability improves and strength drops slightly to 335 MPa. | 335 | 415 | 2.2 | 15 HRC | 3.1 % IACS |
FDefault As fabricated | Pick the standard as-cast pearlitic condition on test bars up to 30 mm for most cylinder blocks and heads; it meets the specified mechanical requirements at 350 MPa yield with no heat treatment. | 350 | 430 | 2 | 17 HRC | 3.1 % IACS |
Normalized | Choose normalizing near 900 °C with air cooling for thick sections or castings low in as-cast pearlite: 400 MPa yield, 255 HB and better wear resistance, but lower ductility and conductivity. | 400 | 500 | 1.2 | 25 HRC | 3 % IACS |
What is A842 Grade 400?
ASTM A842 Grade 400 is a mid-strength compacted graphite iron (EN-GJV-400, RuT400) widely adopted for diesel cylinder blocks and heads that need high fatigue and thermal-fatigue strength in thin walls. Typical properties are 350 MPa yield, 430 MPa tensile, 2 % elongation, 220 HB, 37 W/m·K and service to 350 °C, with F, stress-relieved, normalized and tempered conditions on file. It is the hardest CGI grade to process: machinability score 35 with tool life about one fifth to one half that of grey iron, poor fusion weldability, and a narrow residual Mg/Ti window in the melt. Grade 300 is the choice where lower strength is acceptable. A842 Grade 400 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 400 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 430 MPa (62.4 ksi) — weaker than 74% of steel grades. Elongation at break is 2% and the elastic modulus is 145 GPa (21 Msi).
What is A842 Grade 400 used for?
- diesel engine blocks
- cylinder heads
- brake discs
Advantages
- Low embodied carbon — 1.8 kg CO₂/kg, better than 99% of steel grades
Limitations
- Limited ductility — 2%, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Low stiffness — 145 GPa (21 Msi), worse than 98% of steel grades
- Low fracture toughness — 24 MPa·√m (21.8 ksi·√in), worse than 98% of steel grades
- Low electrical conductivity — 3.1 % IACS, worse than 89% of steel grades
A842 Grade 400 properties
Typical room-temperature values for A842 Grade 400-F; bars are the position among steel grades.
Physical3
A842 Grade 400 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).
Mechanical17
A842 Grade 400 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 430 MPa (62.4 ksi) — weaker than 74% of steel grades. Elongation at break is 2% and the elastic modulus is 145 GPa (21 Msi).
Thermal6
A842 Grade 400 is rated for continuous service to 350°C (662 °F). It conducts heat at 37 W/m·K (21.4 BTU/hr·ft·°F), worse than 71% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
A842 Grade 400 conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of A842 Grade 400 takes about 20 MJ of energy and emits 1.8 kg of CO₂ — less than 99% of steel grades. Typical recycled content is 80%.
Manufacturability8
A842 Grade 400's machinability is fair (35/100, worse than 84% of steel grades); weldability poor (30/100); 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 400 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A842 Grade 400
Is A842 Grade 400 easy to machine?
Distinctly difficult to machine: the as-cast material has no MnS protective film, so run low speed with high feed using CBN or coated carbide, dry or with high-pressure through-tool coolant; tool life is roughly 1/5 to 1/2 that of grey iron.
Can A842 Grade 400 be welded?
Weldability is poor: preheat 300–400 °C and weld small passes with ENiFe/ENi electrodes followed by slow cooling, or use cold welding with short beads and peening; stress relief after welding is recommended.
Can A842 Grade 400 be formed, bent or molded?
Sand or shell cast with strict control of residual Mg and Ti and pre-pour thermal analysis to avoid flake or nodular graphite; feeding requirements lie between grey and ductile iron.
A842 Grade 400 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 |
|---|---|---|
| CASTM A842 does not specify chemistry; typical CGI melt per GB/T 26655 RuT400 | 3.1 – 3.9 | 3.6 |
| Si | 1.7 – 2.6 | 2.2 |
| Mnhigher end stabilises pearlite | 0.2 – 0.6 | 0.4 |
| Cupearlite promoter for Grade 400 | 0.3 – 1 | 0.7 |
| Mgresidual; controls compacted (vermicular) graphite | 0.01 – 0.02 | 0.01 |
| Tioptional anti-nodularising addition; kept low if castings are recycled | 0 – 0.15 | 0.02 |
| Snoptional pearlite stabiliser | 0 – 0.1 | 0.04 |
| P | ≤ 0.06 | 0.03 |
| Slow S required before Mg treatment | ≤ 0.03 | 0.01 |
| Fe | balance | — |
What surface finishes work on A842 Grade 400?
Phosphating, paint or rust-preventive oil is normally used for corrosion protection; cylinder bores can be honed, gas nitrided or laser hardened to improve wear resistance. Anodizing does not apply.
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 400 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- EN-GJV-400
- GB (China)
- RuT400
How much does A842 Grade 400 cost?
A842 Grade 400 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 400 — frequently asked
What is A842 Grade 400 used for?
A842 Grade 400 is typically used for diesel engine blocks, cylinder heads and brake discs. In short: standard diesel block CGI; high thermal-fatigue strength; hard on cutting tools.
What is the yield strength of A842 Grade 400?
A842 Grade 400 has a typical yield strength of 350 MPa (50.8 ksi) and a tensile strength of 430 MPa (62.4 ksi) — weaker than 74% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A842 Grade 400 easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% of steel grades). Distinctly difficult to machine: the as-cast material has no MnS protective film, so run low speed with high feed using CBN or coated carbide, dry or with high-pressure through-tool coolant; tool life is roughly 1/5 to 1/2 that of grey iron.
Can A842 Grade 400 be welded?
Not readily — weldability is rated poor (30/100). Weldability is poor: preheat 300–400 °C and weld small passes with ENiFe/ENi electrodes followed by slow cooling, or use cold welding with short beads and peening; stress relief after welding is recommended.
What surface finishes work on A842 Grade 400?
Phosphating, paint or rust-preventive oil is normally used for corrosion protection; cylinder bores can be honed, gas nitrided or laser hardened to improve wear resistance. Anodizing does not apply.
Can A842 Grade 400 be formed, bent or molded?
Sand or shell cast with strict control of residual Mg and Ti and pre-pour thermal analysis to avoid flake or nodular graphite; feeding requirements lie between grey and ductile iron.
What is the maximum service temperature of A842 Grade 400?
A842 Grade 400 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A842 Grade 400-F and A842 Grade 400 T60-200?
F is the default condition — pick the standard as-cast pearlitic condition on test bars up to 30 mm for most cylinder blocks and heads; it meets the specified mechanical requirements at 350 MPa yield with no heat treatment. T60-200: use for heavy-walled machine-tool castings and large cylinder blocks; graphite coarsening in 60-200 mm sections cuts as-cast strength to 340 MPa tensile, so check designs against these body values. Yield strength is 350 MPa in F versus 295 MPa in T60-200.
How much does A842 Grade 400 cost?
A842 Grade 400 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 (2023)
- EN 16079 — Founding: Compacted (vermicular) graphite cast irons — CEN (2011)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol. 15 — Casting — ASM International (2008)
- SinterCast CGI material properties overview — SinterCast AB (2021)
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.