Steel A352 Grade LC9 QT+PWHT
Heat-treated state
ASTM A352 Grade LC9 · UNS J31300
Condition of weld-repaired castings re-tempered below the original tempering temperature; expect the low end of the strength band and slight toughness scatter at the weld.
Values for the QT+PWHT condition
Other A352 Grade LC9 tempers and conditions
A352 Grade LC9 is listed in 3 conditions; see the grade overview at A352 Grade LC9.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
QT+PWHTThis page quenched and tempered, then post-weld stress relieved after weld repair | Condition of weld-repaired castings re-tempered below the original tempering temperature; expect the low end of the strength band and slight toughness scatter at the weld. | 610 | 875 | 22 | 23 HRC | 3.8 % IACS |
Double normalized and tempered | Alternative A352 route for heavy or complex-section castings where liquid quenching risks distortion or cracking; slightly lower strength, similar cryogenic toughness. | 615 | 880 | 23 | 24 HRC | — |
QTDefault Quenched and tempered | Standard supply condition for LNG valve and pump castings; best combination of 125 ksi strength and −196 °C Charpy energy. | 640 | 900 | 22 | 26 HRC | — |
What is A352 Grade LC9 QT+PWHT?
A352 Grade LC9 QT+PWHT is A352 Grade LC9 heat treated to QT+PWHT — condition of weld-repaired castings re-tempered below the original tempering temperature; expect the low end of the strength band and slight toughness scatter at the weld. A352 Grade LC9 QT+PWHT has a yield strength of 610 MPa (88.5 ksi) and a tensile strength of 875 MPa (127 ksi) — stronger than 77% of steel grades. Elongation at break is 22% and the elastic modulus is 190 GPa (27.6 Msi). A352 Grade LC9 QT+PWHT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,440°C (2,624 °F). QT is the default condition FabDigit quotes; QT+PWHT is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 145 MPa·√m (132 ksi·√in), better than 95% of steel grades
- High strength — 610 MPa (88.5 ksi), better than 77% of steel grades
Limitations
- High embodied carbon — 2.7 kg CO₂/kg, worse than 89% of steel grades
- Poor heat conductor — 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
- Limited formability — 21/100, worse than 77% of steel grades
A352 Grade LC9 QT+PWHT properties
Typical room-temperature values for A352 Grade LC9 QT+PWHT; 22 are specific to this condition. Other listed values are A352 Grade LC9 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A352 Grade LC9 QT+PWHT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,440°C (2,624 °F).
Mechanical16
A352 Grade LC9 QT+PWHT has a yield strength of 610 MPa (88.5 ksi) and a tensile strength of 875 MPa (127 ksi) — stronger than 77% of steel grades. Elongation at break is 22% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal6
A352 Grade LC9 QT+PWHT is rated for continuous service to 340°C (644 °F). It conducts heat at 29 W/m·K (16.8 BTU/hr·ft·°F), worse than 84% of steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical2
A352 Grade LC9 QT+PWHT has an electrical resistivity of 4.5×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of A352 Grade LC9 QT+PWHT takes about 34 MJ of energy and emits 2.7 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 60%.
Manufacturability7
A352 Grade LC9 QT+PWHT's machinability is fair (40/100, worse than 77% of steel grades); weldability fair (48/100); formability poor (21/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A352 Grade LC9 QT+PWHT
Is A352 Grade LC9 easy to machine?
Machine like a 260 HB Q&T alloy steel: rigid setups, coated carbide, moderate speed with generous coolant; the material work-hardens and produces tough, stringy chips.
Can A352 Grade LC9 be welded?
Weld with low heat input using nickel-base fillers (ENiCrMo-6 / ERNiCrMo-3-type) to preserve cryogenic toughness; keep interpass temperature low, avoid magnetic arc blow, and re-temper below the original tempering temperature if PWHT is required.
Can A352 Grade LC9 be formed, bent or molded?
Supplied as sand or investment castings — design generous fillets and directional solidification, and expect a double normalize/quench plus temper cycle with dimensional allowance for distortion.
What surface finishes work on A352 Grade LC9?
No inherent corrosion resistance: shot blast then epoxy or metallize exterior surfaces; machined sealing faces can be polished or hard-faced, and plating is possible with normal low-alloy-steel hydrogen-bake precautions.
A352 Grade LC9 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 ASTM A352 | ≤ 0.13 | 0.08 |
| Mn | ≤ 0.9 | 0.6 |
| Si | ≤ 0.45 | 0.3 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.01 |
| Niprincipal alloying element for cryogenic toughness | 8.5 – 10 | 9 |
| Crresidual element limit | ≤ 0.5 | 0.15 |
| Moresidual element limit | ≤ 0.2 | 0.05 |
| Curesidual element limit | ≤ 0.5 | 0.1 |
| Vresidual element limit | ≤ 0.03 | 0.01 |
| Fe | balance | — |
A352 Grade LC9 QT+PWHT — frequently asked
What is A352 Grade LC9 QT+PWHT used for?
A352 Grade LC9 QT+PWHT is typically used for LNG storage/pipeline fittings, cryogenic valve bodies and gas processing equipment. In short: coldest A352 cast grade; tough to about -320 °F; highest strength, lowest machinability.
What is the yield strength of A352 Grade LC9 QT+PWHT?
A352 Grade LC9 QT+PWHT has a typical yield strength of 610 MPa (88.5 ksi) and a tensile strength of 875 MPa (127 ksi) — stronger than 77% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is A352 Grade LC9 QT+PWHT easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machine like a 260 HB Q&T alloy steel: rigid setups, coated carbide, moderate speed with generous coolant; the material work-hardens and produces tough, stringy chips.
Can A352 Grade LC9 QT+PWHT be welded?
With care — weldability is rated fair (48/100). Weld with low heat input using nickel-base fillers (ENiCrMo-6 / ERNiCrMo-3-type) to preserve cryogenic toughness; keep interpass temperature low, avoid magnetic arc blow, and re-temper below the original tempering temperature if PWHT is required.
What surface finishes work on A352 Grade LC9 QT+PWHT?
No inherent corrosion resistance: shot blast then epoxy or metallize exterior surfaces; machined sealing faces can be polished or hard-faced, and plating is possible with normal low-alloy-steel hydrogen-bake precautions.
Can A352 Grade LC9 QT+PWHT be formed, bent or molded?
Supplied as sand or investment castings — design generous fillets and directional solidification, and expect a double normalize/quench plus temper cycle with dimensional allowance for distortion.
What is the maximum service temperature of A352 Grade LC9 QT+PWHT?
A352 Grade LC9 QT+PWHT is rated for continuous use to about 340°C (644 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A352 Grade LC9-QT and A352 Grade LC9-DNT?
QT is the default condition — standard supply condition for LNG valve and pump castings; best combination of 125 ksi strength and −196 °C Charpy energy. DNT: alternative A352 route for heavy or complex-section castings where liquid quenching risks distortion or cracking; slightly lower strength, similar cryogenic toughness. Yield strength is 640 MPa in QT versus 615 MPa in DNT.
Sources
- ASTM A352/A352M — Steel Castings, Ferritic and Martensitic, for Pressure-Containing Parts, Suitable for Low-Temperature Service — ASTM International (2023)
- ASME BPVC Section II Part D — Properties (Metric), 9Ni steel allowable stresses and physical properties — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys (9 % Ni cryogenic steels) — ASM International (1990)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- ASTM E140 — Standard Hardness Conversion Tables for Metals — ASTM International (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.