Steel A842 Grade 400-SR (Stress relieved)
Heat-treated state
ASTM A842 Grade 400 · EN EN-GJV-400 · GB RuT400
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.
Values for the SR condition
Other A842 Grade 400 tempers and conditions
A842 Grade 400 is listed in 5 conditions; see the grade overview at A842 Grade 400.
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 |
SRThis page 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-SR?
A842 Grade 400-SR is A842 Grade 400 heat treated to SR — 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. A842 Grade 400-SR has a yield strength of 335 MPa (48.6 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 77% of steel grades. Elongation at break is 2.2% and the elastic modulus is 145 GPa (21 Msi). A842 Grade 400-SR 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). F is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Low embodied carbon — 1.8 kg CO₂/kg, better than 99% of steel grades
Limitations
- Limited ductility — 2.2%, 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-SR properties
Typical room-temperature values for A842 Grade 400-SR; 23 are specific to this condition. Other listed values are A842 Grade 400 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A842 Grade 400-SR 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-SR has a yield strength of 335 MPa (48.6 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 77% of steel grades. Elongation at break is 2.2% and the elastic modulus is 145 GPa (21 Msi).
Thermal6
A842 Grade 400-SR 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-SR 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-SR 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-SR's machinability is fair (38/100, worse than 80% of steel grades); weldability fair (35/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A842 Grade 400-SR
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.
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.
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 | — |
A842 Grade 400-SR — frequently asked
What is A842 Grade 400-SR used for?
A842 Grade 400-SR 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-SR?
A842 Grade 400-SR has a typical yield strength of 335 MPa (48.6 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 77% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A842 Grade 400-SR easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% 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-SR be welded?
With care — weldability is rated fair (35/100). 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-SR?
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-SR 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-SR?
A842 Grade 400-SR 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.