Steel A356 Grade 9
ASTM A356 Grade 9 · UNS J21610
ASTM A356 Grade 9 (UNS J21610) is a 9Cr-1Mo air-hardening alloy steel casting that combines high creep strength with oxidation resistance for high-temperature steam and reformer service.
Reference datasheet — A356 Grade 9 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 9 tempers and conditions
A356 Grade 9 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 |
|---|---|---|---|---|---|---|
full anneal (soft condition, machining/repair) | Soft intermediate condition used for heavy machining or weld repair before final normalize-and-temper; not a service condition. | 330 | 570 | 26 | 165 HB | 3 % IACS |
N+T + post-weld heat treatment / stress relief | Condition of a finished, weld-repaired or fabricated casting after mandatory PWHT; slightly softer than as-tempered material. | 455 | 660 | 21 | 11 HRC | 2.9 % IACS |
N+TDefault Normalized and tempered | Standard supply condition for heavy-walled turbine casings and valve bodies; balanced creep strength and toughness. | 480 | 690 | 20 | 14 HRC | 2.9 % IACS |
Quenched and tempered | Chosen for thick sections where a fully martensitic through-hardened structure and the upper end of the strength band are needed. | 540 | 740 | 19 | 21 HRC | — |
What is A356 Grade 9?
ASTM A356 Grade 9 (UNS J21610) is a 9Cr-1Mo air-hardening alloy steel casting that combines high creep strength with oxidation resistance for high-temperature steam and reformer service. Default properties are 480 MPa yield, 690 MPa tensile, 20 % elongation and 200 HB, with service to 600 °C; conditions on file are N+T, Q+T, annealed and N+T+SR, supplied as sand or investment castings. The martensitic matrix makes 200–300 °C preheat and a 730–760 °C temper mandatory after welding, and the alloy is not stainless — machined surfaces rust at ambient conditions. Grade 8 (5Cr-1/2Mo) is the alternative when 9Cr creep strength is not needed. A356 Grade 9 has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,420°C (2,588 °F). A356 Grade 9 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 59% of steel grades. Elongation at break is 20% and the elastic modulus is 207 GPa (30 Msi).
What is A356 Grade 9 used for?
- reformer components
- high-temperature steam piping fittings
- power plant castings
Advantages
- High service temperature — 600°C (1,112 °F), better than 98% 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 — 2.9 % IACS, worse than 93% of steel grades
- Poor heat conductor — 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades
A356 Grade 9 properties
Typical room-temperature values for A356 Grade 9-N+T; bars are the position among steel grades.
Physical3
A356 Grade 9 has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical17
A356 Grade 9 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 59% of steel grades. Elongation at break is 20% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A356 Grade 9 is rated for continuous service to 600°C (1,112 °F). It conducts heat at 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
A356 Grade 9 conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of A356 Grade 9 takes about 32 MJ of energy and emits 2.4 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 70%.
Manufacturability7
A356 Grade 9's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (40/100); 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 9 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A356 Grade 9
Is A356 Grade 9 easy to machine?
Machine in the tempered condition with rigid setups, carbide inserts, moderate speed and heavy feed; the air-hardening matrix work-hardens and is abrasive, so avoid dwell and interrupted light cuts.
Can A356 Grade 9 be welded?
Weld with matching 9Cr-1Mo filler (E505/ER80S-B8 class), 200–300 °C preheat and interpass, no cooling below preheat before PWHT, then temper 730–760 °C; martensite in the HAZ makes skipped PWHT a cracking risk.
Can A356 Grade 9 be formed, bent or molded?
Supplied as sand or investment castings — feed heavy sections generously, control hot tearing, and always normalize-and-temper (or quench-and-temper) since as-cast material has unacceptable toughness.
A356 Grade 9 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 |
|---|---|---|
| Cmax per specification | ≤ 0.2 | 0.13 |
| Si | ≤ 1 | 0.5 |
| Mn | 0.3 – 0.7 | 0.5 |
| Pheavy-wall turbine practice often ≤0.020 | ≤ 0.04 | 0.02 |
| Sheavy-wall turbine practice often ≤0.020 | ≤ 0.04 | 0.01 |
| Cr | 8 – 10 | 9 |
| Mo | 0.9 – 1.2 | 1 |
| Niresidual | ≤ 0.5 | 0.2 |
| Fe | balance | — |
What surface finishes work on A356 Grade 9?
Shot-blast and either paint with high-temperature silicone/aluminium coating or leave bare for hot service; not stainless, so machined surfaces need oiling or coating to prevent ambient rusting; not anodizable.
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 9 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J21610
How much does A356 Grade 9 cost?
A356 Grade 9 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 9 — frequently asked
What is A356 Grade 9 used for?
A356 Grade 9 is typically used for reformer components, high-temperature steam piping fittings and power plant castings. In short: highest-creep Cr-Mo casting here; martensitic, air-hardening grade; skipped PWHT means cracking.
What is the yield strength of A356 Grade 9?
A356 Grade 9 has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 690 MPa (100 ksi) — stronger than 59% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A356 Grade 9 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the tempered condition with rigid setups, carbide inserts, moderate speed and heavy feed; the air-hardening matrix work-hardens and is abrasive, so avoid dwell and interrupted light cuts.
Can A356 Grade 9 be welded?
With care — weldability is rated fair (40/100). Weld with matching 9Cr-1Mo filler (E505/ER80S-B8 class), 200–300 °C preheat and interpass, no cooling below preheat before PWHT, then temper 730–760 °C; martensite in the HAZ makes skipped PWHT a cracking risk.
What surface finishes work on A356 Grade 9?
Shot-blast and either paint with high-temperature silicone/aluminium coating or leave bare for hot service; not stainless, so machined surfaces need oiling or coating to prevent ambient rusting; not anodizable.
Can A356 Grade 9 be formed, bent or molded?
Supplied as sand or investment castings — feed heavy sections generously, control hot tearing, and always normalize-and-temper (or quench-and-temper) since as-cast material has unacceptable toughness.
What is the maximum service temperature of A356 Grade 9?
A356 Grade 9 is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does A356 Grade 9 cost?
A356 Grade 9 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 — Martensitic Stainless and Alloy Steel Castings for Pressure-Containing Parts (Grade C12) — ASTM International (2021)
- ASME BPVC Section II Part D — Materials, Properties (9Cr-1Mo) — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering (Cr-Mo steels) — ASM International (1993)
- GB/T 16253 — (ZG12Cr9Mo1 ) — SAC (2019)
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.