Steel A356 Grade 8
ASTM A356 Grade 8 · UNS J11697
ASTM A356 Grade 8 (UNS J11697) is a 5Cr-1/2Mo air-hardening alloy steel casting for elevated-temperature service in petrochemical and power-generation equipment where oxidation resistance matters.
Reference datasheet — A356 Grade 8 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 N+T condition
A356 Grade 8 tempers and conditions
A356 Grade 8 is supplied in 4 conditions, soft to hard. N+T 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 |
|---|---|---|---|---|---|---|
Solution annealed | Pick when maximum machinability or softest condition for heavy welding/repair is needed before final heat treatment. | 365 | 585 | 24 | 160 HB | 3.9 % IACS |
normalized, tempered and post-weld heat treated / stress relieved | Condition of weld-repaired or fabricated castings after a 700–750 °C stress-relief cycle; slightly lower strength, best toughness and dimensional stability. | 430 | 620 | 22 | 12 HRC | 3.8 % IACS |
N+TDefault Normalized and tempered | Standard delivery condition for A356 Gr.8 turbine and valve castings: balanced strength, creep resistance and toughness. | 450 | 655 | 20 | 15 HRC | 3.8 % IACS |
Quenched and tempered | Used for thinner-section castings needing higher strength and uniform properties; tempering above 620 °C keeps it stable for hot service. | 550 | 725 | 18 | 21 HRC | — |
What is A356 Grade 8?
ASTM A356 Grade 8 (UNS J11697) is a 5Cr-1/2Mo air-hardening alloy steel casting for elevated-temperature service in petrochemical and power-generation equipment where oxidation resistance matters. Default properties are 450 MPa yield, 655 MPa tensile, 20 % elongation and 200 HB, with service to 620 °C; conditions on file are N+T, annealed, Q+T and N+T+PWHT. Because the alloy air-hardens, 200–300 °C preheat and a 700–760 °C post-weld temper are mandatory, and the chromium carbides are abrasive to tooling. Grade 6 (2-1/4Cr-1Mo) is the lower-alloy option below 550 °C; Grade 9 (9Cr-1Mo) is the step up. A356 Grade 8 has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,425°C (2,597 °F). A356 Grade 8 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 52% of steel grades. Elongation at break is 20% and the elastic modulus is 207 GPa (30 Msi).
What is A356 Grade 8 used for?
- petrochemical process equipment
- high-temperature valve bodies
- furnace components
Advantages
- High service temperature — 620°C (1,148 °F), better than 99% of steel grades
- Good corrosion resistance — 30/100, better than 95% of steel grades
Limitations
- Limited formability — 10/100, worse than 95% of steel grades
- Low electrical conductivity — 3.8 % IACS, worse than 84% of steel grades
- Poor heat conductor — 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades
A356 Grade 8 properties
Typical room-temperature values for A356 Grade 8-N+T; bars are the position among steel grades.
Physical3
A356 Grade 8 has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical17
A356 Grade 8 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 52% of steel grades. Elongation at break is 20% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A356 Grade 8 is rated for continuous service to 620°C (1,148 °F). It conducts heat at 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
A356 Grade 8 conducts electricity at 3.8 % IACS, worse than 84% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of A356 Grade 8 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 80%.
Manufacturability8
A356 Grade 8's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (45/100); formability not recommended (10/100).
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. A356 Grade 8 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A356 Grade 8
Is A356 Grade 8 easy to machine?
Machine in the N+T or annealed condition with rigid setups, carbide tooling and moderate speeds (~60–90 m/min); chromium carbides are abrasive and cast skin should be removed first.
Can A356 Grade 8 be welded?
Weldable with matching 5Cr-0.5Mo (E/ER 502) consumables using 200–300 °C preheat, controlled interpass temperature and a mandatory 700–760 °C post-weld temper to avoid hard martensitic HAZ and hydrogen cracking.
Can A356 Grade 8 be formed, bent or molded?
Supplied as sand castings — design generous fillets and directional solidification for heavy walls; the alloy air-hardens, so slow, controlled cooling from casting temperature is required.
A356 Grade 8 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 |
|---|---|---|
| Ccarbon kept low for weldability of heavy sections | ≤ 0.2 | 0.15 |
| Mn | 0.4 – 0.7 | 0.55 |
| Si | ≤ 0.75 | 0.45 |
| Pheavy-walled turbine castings often ordered to tighter P/S | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Crprovides steam-oxidation and sulfidation resistance | 4 – 6.5 | 5 |
| Mocreep strength | 0.45 – 0.65 | 0.55 |
| Niresidual | ≤ 0.5 | 0.2 |
| Fe | balance | — |
What surface finishes work on A356 Grade 8?
Not anodizable; protect with high-temperature aluminium/silicone paint, aluminizing or thermal-spray coatings for outdoor and cyclic-service parts.
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 A356 Grade 8 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J11697
How much does A356 Grade 8 cost?
A356 Grade 8 is a premium-cost steel ($$$), cheaper than about 51% 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.
A356 Grade 8 — frequently asked
What is A356 Grade 8 used for?
A356 Grade 8 is typically used for petrochemical process equipment, high-temperature valve bodies and furnace components. In short: 5Cr-0.5Mo oxidation resistance; air-hardening cast steel; service to 620 °C.
What is the yield strength of A356 Grade 8?
A356 Grade 8 has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 52% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A356 Grade 8 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the N+T or annealed condition with rigid setups, carbide tooling and moderate speeds (~60–90 m/min); chromium carbides are abrasive and cast skin should be removed first.
Can A356 Grade 8 be welded?
With care — weldability is rated fair (45/100). Weldable with matching 5Cr-0.5Mo (E/ER 502) consumables using 200–300 °C preheat, controlled interpass temperature and a mandatory 700–760 °C post-weld temper to avoid hard martensitic HAZ and hydrogen cracking.
What surface finishes work on A356 Grade 8?
Not anodizable; protect with high-temperature aluminium/silicone paint, aluminizing or thermal-spray coatings for outdoor and cyclic-service parts.
Can A356 Grade 8 be formed, bent or molded?
Supplied as sand castings — design generous fillets and directional solidification for heavy walls; the alloy air-hardens, so slow, controlled cooling from casting temperature is required.
What is the maximum service temperature of A356 Grade 8?
A356 Grade 8 is rated for continuous use to about 620°C (1,148 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A356 Grade 8 N+T and A356 Grade 8-A?
N+T is the default condition — standard delivery condition for A356 Gr.8 turbine and valve castings: balanced strength, creep resistance and toughness. A: pick when maximum machinability or softest condition for heavy welding/repair is needed before final heat treatment. Yield strength is 450 MPa in N+T versus 365 MPa in A.
How much does A356 Grade 8 cost?
A356 Grade 8 is a premium-cost steel ($$$), cheaper than about 51% 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 A356/A356M — Steel Castings, Carbon, Low Alloy, and Stainless Steel, Heavy-Walled for Steam Turbines — ASTM International (2021)
- ASTM A217/A217M — Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts, High-Temperature Service — ASTM International (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASME BPVC Section II Part D — Material Properties (5Cr-1/2Mo) — ASME (2023)
- Steel Castings Handbook — Steel Founders' Society of America / ASM (1995)
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.