Steel A356 Grade 5 Q&T (Quenched and tempered)
Heat-treated state
ASTM A356 Grade 5 · UNS J12540
Choose when higher yield strength and uniform through-thickness properties are needed in thick sections.
Values for the Q&T condition
Other A356 Grade 5 tempers and conditions
A356 Grade 5 is listed in 4 conditions; see the grade overview at A356 Grade 5.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition, used for rough machining or repair welding before final normalize-and-temper. | 290 | 490 | 28 | 145 HB | 8 % IACS |
N+T + simulated post-weld heat treatment | Test condition for castings that will see long or repeated PWHT cycles at 690–730 °C; strength drops slightly, toughness recovers. | 320 | 520 | 26 | 160 HB | 7.8 % IACS |
N+TDefault Normalized and tempered | Standard supply condition for heavy-walled turbine casings; best balance of creep strength, toughness and dimensional stability. | 345 | 550 | 24 | 10 HRC | 7.8 % IACS |
Q&TThis page Quenched and tempered | Choose when higher yield strength and uniform through-thickness properties are needed in thick sections. | 450 | 620 | 21 | 15 HRC | — |
What is A356 Grade 5 Q&T?
A356 Grade 5 Q&T is A356 Grade 5 heat treated to Q&T — choose when higher yield strength and uniform through-thickness properties are needed in thick sections. A356 Grade 5 Q&T has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 52% of steel grades. Elongation at break is 21% and the elastic modulus is 207 GPa (30 Msi). A356 Grade 5 Q&T has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F). N+T is the default condition FabDigit quotes; Q&T is available on request or by drawing note.
Advantages
- High service temperature — 540°C (1,004 °F), better than 93% of steel grades
- Tough — resists crack growth — 120 MPa·√m (109.2 ksi·√in), better than 81% of steel grades
Limitations
- Limited formability — 20/100, worse than 80% of steel grades
A356 Grade 5 Q&T properties
Typical room-temperature values for A356 Grade 5 Q&T; 10 are specific to this condition. Other listed values are A356 Grade 5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A356 Grade 5 Q&T has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical17
A356 Grade 5 Q&T has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 52% of steel grades. Elongation at break is 21% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A356 Grade 5 Q&T is rated for continuous service to 540°C (1,004 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
A356 Grade 5 Q&T conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of A356 Grade 5 Q&T takes about 27 MJ of energy and emits 2.1 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 75%.
Manufacturability8
A356 Grade 5 Q&T's machinability is fair (52/100, better than 52% of steel grades); weldability good (55/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A356 Grade 5 Q&T
Is A356 Grade 5 easy to machine?
Machines like a 170 HB alloy steel — use rigid setups, carbide tooling at 80–140 m/min, and expect abrasive cast skin and possible sand inclusions on the first cut.
Can A356 Grade 5 be welded?
Weldable with matched 1.25Cr-0.5Mo (E8018-B2 / ER80S-B2) consumables; 200–300 °C preheat/interpass and 690–730 °C PWHT are mandatory to avoid hydrogen cracking.
Can A356 Grade 5 be formed, bent or molded?
Supplied only as sand castings; heavy sections need generous risering, chills and controlled solidification, followed by full re-austenitizing heat treatment.
What surface finishes work on A356 Grade 5?
Not anodizable; protect with high-temperature aluminum/silicone paint, metallizing or aluminizing, and radiograph/MT-inspect surfaces before coating.
A356 Grade 5 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 | 0.5 – 0.8 | 0.65 |
| Si | ≤ 0.6 | 0.4 |
| Pkept low to limit temper embrittlement | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Cr | 1 – 1.5 | 1.25 |
| Mo | 0.45 – 0.65 | 0.55 |
| Niresidual | ≤ 0.5 | — |
| Curesidual | ≤ 0.35 | — |
| Fe | balance | — |
A356 Grade 5 Q&T — frequently asked
What is A356 Grade 5 Q&T used for?
A356 Grade 5 Q&T is typically used for steam turbine casings, high-temperature valve bodies and power plant fittings. In short: classic 1.25Cr-0.5Mo casting; creep service to 550 °C; mandatory PWHT after welding.
What is the yield strength of A356 Grade 5 Q&T?
A356 Grade 5 Q&T has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 52% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A356 Grade 5 Q&T easy to machine?
Reasonably — machinability is rated fair (52/100, better than 52% of steel grades). Machines like a 170 HB alloy steel — use rigid setups, carbide tooling at 80–140 m/min, and expect abrasive cast skin and possible sand inclusions on the first cut.
Can A356 Grade 5 Q&T be welded?
Yes — weldability is rated good (55/100). Weldable with matched 1.25Cr-0.5Mo (E8018-B2 / ER80S-B2) consumables; 200–300 °C preheat/interpass and 690–730 °C PWHT are mandatory to avoid hydrogen cracking.
What surface finishes work on A356 Grade 5 Q&T?
Not anodizable; protect with high-temperature aluminum/silicone paint, metallizing or aluminizing, and radiograph/MT-inspect surfaces before coating.
Can A356 Grade 5 Q&T be formed, bent or molded?
Supplied only as sand castings; heavy sections need generous risering, chills and controlled solidification, followed by full re-austenitizing heat treatment.
What is the maximum service temperature of A356 Grade 5 Q&T?
A356 Grade 5 Q&T is rated for continuous use to about 540°C (1,004 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A356 Grade 5 N+T and A356 Grade 5-ANN?
N+T is the default condition — standard supply condition for heavy-walled turbine casings; best balance of creep strength, toughness and dimensional stability. ANN: softest condition, used for rough machining or repair welding before final normalize-and-temper. Yield strength is 345 MPa in N+T versus 290 MPa in ANN.
Sources
- ASTM A356/A356M — Steel Castings, Carbon, Low Alloy, and Stainless Steel, Heavy-Walled for Steam Turbines — ASTM International (2021)
- ASME BPVC Section II Part D — Material Properties (1-1/4Cr-1/2Mo) — ASME (2023)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 13A — Corrosion: Fundamentals, Testing, and Protection — ASM International (2003)
- GB/T 16253 / ZG15Cr1Mo — 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.