Steel A356 Grade 9 Q+T
Heat-treated state
ASTM A356 Grade 9 · UNS J21610
Q+T = quenched and tempered
Chosen for thick sections where a fully martensitic through-hardened structure and the upper end of the strength band are needed.
Values for the Q+T condition
Other A356 Grade 9 tempers and conditions
A356 Grade 9 is listed in 4 conditions; see the grade overview at A356 Grade 9.
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 |
Q+TThis page 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 Q+T?
A356 Grade 9 Q+T is A356 Grade 9 heat treated to Q+T — chosen for thick sections where a fully martensitic through-hardened structure and the upper end of the strength band are needed. A356 Grade 9 Q+T has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 740 MPa (107 ksi) — stronger than 70% of steel grades. Elongation at break is 19% and the elastic modulus is 207 GPa (30 Msi). A356 Grade 9 Q+T 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). N+T is the default condition FabDigit quotes; Q+T is available on request or by drawing note.
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 Q+T properties
Typical room-temperature values for A356 Grade 9 Q+T; 10 are specific to this condition. Other listed values are A356 Grade 9 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A356 Grade 9 Q+T 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 Q+T has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 740 MPa (107 ksi) — stronger than 70% of steel grades. Elongation at break is 19% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A356 Grade 9 Q+T 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 Q+T 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 Q+T 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 Q+T's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (40/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A356 Grade 9 Q+T
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.
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.
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 | — |
A356 Grade 9 Q+T — frequently asked
What is A356 Grade 9 Q+T used for?
A356 Grade 9 Q+T 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 Q+T?
A356 Grade 9 Q+T has a typical yield strength of 540 MPa (78.3 ksi) and a tensile strength of 740 MPa (107 ksi) — stronger than 70% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A356 Grade 9 Q+T 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 Q+T 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 Q+T?
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 Q+T 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 Q+T?
A356 Grade 9 Q+T 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.