Steel A369 FP5 Q&T (Quenched and tempered)
Heat-treated state
ASTM A369 FP5
Special-order condition for thick FP5 forgings/valve bodies needing maximum toughness and through-thickness uniform strength; requires temper well above expected service temperature.
Values for the Q&T condition
Other A369 FP5 tempers and conditions
A369 FP5 is listed in 3 conditions; see the grade overview at A369 FP5.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault full anneal per ASTM A369 (soften, ≤179 HB) | Default stock condition for FP5 forged-and-bored pipe: softest, best machinability and bendability, meets 415 MPa UTS / 205 MPa YS minima. | 305 | 500 | 30 | 150 HB | — |
Normalized and tempered | Pick when higher strength, finer grain and better creep/impact performance are wanted for pressure piping and furnace headers. | 400 | 585 | 24 | 175 HB | — |
Q&TThis page Quenched and tempered | Special-order condition for thick FP5 forgings/valve bodies needing maximum toughness and through-thickness uniform strength; requires temper well above expected service temperature. | 480 | 640 | 21 | 15 HRC | 2.8 % IACS |
What is A369 FP5 Q&T?
A369 FP5 Q&T is A369 FP5 heat treated to Q&T — special-order condition for thick FP5 forgings/valve bodies needing maximum toughness and through-thickness uniform strength; requires temper well above expected service temperature. A369 FP5 Q&T has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 59% of steel grades. Elongation at break is 21% and the elastic modulus is 213 GPa (30.9 Msi). A369 FP5 Q&T has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,450°C (2,642 °F). Annealed is the default condition FabDigit quotes; Q&T is available on request or by drawing note.
Advantages
- High service temperature — 595°C (1,103 °F), better than 97% of steel grades
- Good corrosion resistance — 30/100, better than 95% of steel grades
- Tough — resists crack growth — 125 MPa·√m (113.8 ksi·√in), better than 85% of steel grades
Limitations
- Low electrical conductivity — 2.8 % IACS, worse than 94% of steel grades
- Difficult to machine — 38/100, worse than 80% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
A369 FP5 Q&T properties
Typical room-temperature values for A369 FP5 Q&T; 23 are specific to this condition. Other listed values are A369 FP5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A369 FP5 Q&T has a density of 7.78 g/cm³ (0.281 lb/in³), lighter than 91% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
A369 FP5 Q&T has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 59% of steel grades. Elongation at break is 21% and the elastic modulus is 213 GPa (30.9 Msi).
Thermal6
A369 FP5 Q&T is rated for continuous service to 595°C (1,103 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
A369 FP5 Q&T conducts electricity at 2.8 % IACS, worse than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (30/100), better than 95% of steel grades.
Sustainability4
Producing a kilogram of A369 FP5 Q&T takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 25%.
Manufacturability7
A369 FP5 Q&T's machinability is fair (38/100, worse than 80% of steel grades); weldability fair (35/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A369 FP5 Q&T
Is A369 FP5 easy to machine?
Machine in the annealed condition with rigid setups, carbide tooling and moderate speeds (~60–90 m/min); the chromium carbides are abrasive and the steel work-hardens if feeds are too light.
Can A369 FP5 be welded?
Weld with matching 5Cr-0.5Mo filler (E8018-B6 / ER80S-B6), preheat and interpass 200–260 °C, and PWHT 700–760 °C — the alloy air-hardens and cold-cracks readily without it.
Can A369 FP5 be formed, bent or molded?
Bend and expand hot (900–1050 °C) whenever possible; cold bending is limited and must be followed by a stress-relief or full re-heat-treatment.
What surface finishes work on A369 FP5?
Not anodizable; protect with high-temperature aluminium/silicone paint, aluminizing or chromizing, and keep insulation dry to avoid corrosion under insulation.
A369 FP5 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 |
|---|---|---|
| C0.15 % max per ASTM A369/A335 grade P5 | ≤ 0.15 | 0.12 |
| Mn | 0.3 – 0.6 | 0.45 |
| SiFP5b variant runs 1.00–2.00 Si | ≤ 0.5 | 0.3 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.03 | 0.01 |
| Cr | 4 – 6 | 5 |
| Mo | 0.45 – 0.65 | 0.55 |
| Fe | balance | — |
A369 FP5 Q&T — frequently asked
What is A369 FP5 Q&T used for?
A369 FP5 Q&T is typically used for refinery hydroprocessing piping, high-temperature process piping, hot sulfidic gas oil and naphtha lines, catalytic reformer piping, fired heater outlet and transfer piping and forged fittings for 5Cr-0.5Mo systems. In short: 5Cr for sulfidic service; rated to 620 °C; air-hardening Cr-Mo pipe.
What is the yield strength of A369 FP5 Q&T?
A369 FP5 Q&T has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 59% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is A369 FP5 Q&T easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% of steel grades). Machine in the annealed condition with rigid setups, carbide tooling and moderate speeds (~60–90 m/min); the chromium carbides are abrasive and the steel work-hardens if feeds are too light.
Can A369 FP5 Q&T be welded?
With care — weldability is rated fair (35/100). Weld with matching 5Cr-0.5Mo filler (E8018-B6 / ER80S-B6), preheat and interpass 200–260 °C, and PWHT 700–760 °C — the alloy air-hardens and cold-cracks readily without it.
What surface finishes work on A369 FP5 Q&T?
Not anodizable; protect with high-temperature aluminium/silicone paint, aluminizing or chromizing, and keep insulation dry to avoid corrosion under insulation.
Can A369 FP5 Q&T be formed, bent or molded?
Bend and expand hot (900–1050 °C) whenever possible; cold bending is limited and must be followed by a stress-relief or full re-heat-treatment.
What is the maximum service temperature of A369 FP5 Q&T?
A369 FP5 Q&T is rated for continuous use to about 595°C (1,103 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM A369/A369M — Carbon and Ferritic Alloy Steel Forged and Bored Pipe for High-Temperature Service — ASTM International (2018)
- ASTM A335/A335M — Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service (Grade P5) — ASTM International (2022)
- EN 10216-2 / DIN 17175 — X12CrMo5 (1.7362) seamless tubes — CEN / DIN (2020)
- GB/T 9948 — (12Cr5MoI) — SAC (2013)
- ASME BPVC Section II Part D — Material Properties (5Cr-0.5Mo) — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- API 941 — Steels for Hydrogen Service at Elevated Temperatures — API (2016)
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.