Steel P305GH +QT (Quenched and tempered)
Heat-treated state
EN P305GH
Chosen for thick-section forgings (flanges, valve bodies) where through-thickness yield and toughness must be held at the top of the band.
Values for the +QT condition
Other P305GH tempers and conditions
P305GH is listed in 5 conditions; see the grade overview at P305GH.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Intermediate soft condition for heavy machining or cold forming; must be re-normalized before pressure service. | 280 | 470 | 30 | 135 HB | 9.8 % IACS |
Normalized and tempered | Used for heavier forgings/bars where a stress-relieving temper follows normalizing; slightly lower strength, better toughness scatter. | 325 | 520 | 26 | 150 HB | 9.6 % IACS |
Hot rolled | Lowest-cost bar condition for non-critical or later-heat-treated parts; property scatter is wider and grain size is not guaranteed. | 330 | 545 | 22 | 160 HB | 9.6 % IACS |
+NDefault Normalized | Standard supply condition for pressure bars, plate and forgings; fine grain, guaranteed 305 MPa yield and 27 J CVN. | 340 | 540 | 24 | 155 HB | — |
+QTThis page Quenched and tempered | Chosen for thick-section forgings (flanges, valve bodies) where through-thickness yield and toughness must be held at the top of the band. | 380 | 570 | 24 | 170 HB | 9.6 % IACS |
What is P305GH +QT?
P305GH +QT is P305GH heat treated to +QT — chosen for thick-section forgings (flanges, valve bodies) where through-thickness yield and toughness must be held at the top of the band. P305GH +QT has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 68% of steel grades. Elongation at break is 24% and the elastic modulus is 212 GPa (30.7 Msi). P305GH +QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F). +N is the default condition FabDigit quotes; +QT is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 140 MPa·√m (127.4 ksi·√in), better than 94% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Readily welded — 82/100, better than 81% of steel grades
- High electrical conductivity — 9.6 % IACS, better than 78% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
P305GH +QT properties
Typical room-temperature values for P305GH +QT; 22 are specific to this condition. Other listed values are P305GH reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
P305GH +QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F).
Mechanical16
P305GH +QT has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 68% of steel grades. Elongation at break is 24% and the elastic modulus is 212 GPa (30.7 Msi).
Thermal6
P305GH +QT is rated for continuous service to 400°C (752 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), better than 75% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
P305GH +QT conducts electricity at 9.6 % IACS, better than 78% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of P305GH +QT takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
P305GH +QT's machinability is good (55/100, better than 62% of steel grades); weldability very good (82/100); formability good (58/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with P305GH +QT
Is P305GH easy to machine?
Machines like a normalized C-Mn steel (~60 % of AISI 1212); low sulphur means stringy chips — use positive-rake carbide, generous feed and coolant to avoid built-up edge.
Can P305GH be welded?
Readily welded by SMAW/SAW/GTAW/GMAW with matching C-Mn consumables; CEV ≈ 0.40–0.45 so preheat 100–150 °C above ~30 mm and apply PWHT 580–620 °C per code.
Can P305GH be formed, bent or molded?
Hot form 850–1050 °C followed by re-normalizing; cold bending is possible with generous radii (≥2t) but heavy cold work should be normalized out before pressure service.
What surface finishes work on P305GH?
No anodizing; shot-blast then zinc-rich primer, epoxy paint, hot-dip galvanizing or corrosion allowance — bare surfaces rust quickly in humid service.
P305GH 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 |
|---|---|---|
| Cladle analysis | ≤ 0.22 | 0.18 |
| Si | 0.1 – 0.4 | 0.3 |
| Mn | 0.9 – 1.5 | 1.2 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.02 | 0.01 |
| Altotal Al, grain refining | ≥ 0.02 | 0.03 |
| Crresidual | ≤ 0.3 | 0.1 |
| Curesidual | ≤ 0.3 | 0.1 |
| Moresidual | ≤ 0.08 | 0.02 |
| Niresidual | ≤ 0.3 | 0.1 |
| Nb | ≤ 0.02 | — |
| Ti | ≤ 0.03 | — |
| V | ≤ 0.02 | — |
| N | ≤ 0.01 | 0.01 |
| Fe | balance | — |
P305GH +QT — frequently asked
What is P305GH +QT used for?
P305GH +QT is typically used for boiler drums, pressure vessel shells, steam piping flanges and heat exchanger components. In short: higher-strength pressure vessel steel; code elevated-temperature service; preheat needed on thick sections.
What is the yield strength of P305GH +QT?
P305GH +QT has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is P305GH +QT easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like a normalized C-Mn steel (~60 % of AISI 1212); low sulphur means stringy chips — use positive-rake carbide, generous feed and coolant to avoid built-up edge.
Can P305GH +QT be welded?
Yes — weldability is rated very good (82/100). Readily welded by SMAW/SAW/GTAW/GMAW with matching C-Mn consumables; CEV ≈ 0.40–0.45 so preheat 100–150 °C above ~30 mm and apply PWHT 580–620 °C per code.
What surface finishes work on P305GH +QT?
No anodizing; shot-blast then zinc-rich primer, epoxy paint, hot-dip galvanizing or corrosion allowance — bare surfaces rust quickly in humid service.
Can P305GH +QT be formed, bent or molded?
Hot form 850–1050 °C followed by re-normalizing; cold bending is possible with generous radii (≥2t) but heavy cold work should be normalized out before pressure service.
What is the maximum service temperature of P305GH +QT?
P305GH +QT is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN 10273 — Hot rolled weldable steel bars for pressure purposes with specified elevated temperature properties — CEN (2016)
- EN 10222-2 — Steel forgings for pressure purposes: ferritic and martensitic steels with specified elevated temperature properties — CEN (2021)
- EN 10028-2 — Flat products made of steels for pressure purposes: non-alloy and alloy steels with specified elevated temperature properties — CEN (2017)
- EN 10027-2 / CR 10260 — Steel numbering system (1.0436) — CEN (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- EN 1011-2 — Welding recommendations for ferritic steels — CEN (2001)
- Mysteel / SMM (2025)
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.