Steel P355Q
EN 1.8866, 10028-6
P355Q (1.8866) is the base quenched and tempered grade of the EN 10028-6 Q series, a low-alloy fine-grain pressure vessel steel in the 355 MPa yield class.
Reference datasheet — P355Q is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the QT condition
P355Q tempers and conditions
P355Q is supplied in 7 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
QT | Thick-section vessel shells and forged-plate substitutes; lowest strength class of the grade. | 355 | 520 | 24 | 160 HB | 8.2 % IACS |
QT | Heavy plate condition; mandatory strength de-rating due to lower quench severity in section. | 380 | 540 | 25 | 168 HB | 8.2 % IACS |
quenched, tempered and post-weld stress relieved (simulated PWHT) | Specify when vessel fabrication requires PWHT; plate is delivered tested in the simulated PWHT condition with slightly softened properties. | 385 | 540 | 27 | 168 HB | 8.2 % IACS |
QTDefault Quenched and tempered | Standard stocked condition for pressure-vessel plate up to 50 mm; full 355 MPa yield class. | 400 | 560 | 26 | 175 HB | — |
Q&T, elevated-temperature properties guaranteed | Choose when the code case needs guaranteed proof stress at elevated temperature plus −20 °C impact values. | 400 | 560 | 26 | 175 HB | 8.2 % IACS |
Q&T, low-temperature grade, impact at −40 °C | Pick for cold-climate or refrigerated service down to about −40 °C. | 400 | 560 | 26 | 175 HB | 8.2 % IACS |
Q&T, low-temperature grade, impact at −60 °C | Cleanest chemistry of the family (low P/S) for LPG/ammonia and Arctic vessels down to −60 °C. | 405 | 560 | 27 | 175 HB | 8.2 % IACS |
What is P355Q?
P355Q (1.8866) is the base quenched and tempered grade of the EN 10028-6 Q series, a low-alloy fine-grain pressure vessel steel in the 355 MPa yield class. It is chosen when good weldability matters more than maximum strength, and is available as plate in QT and QT+SR up to 150 mm, with the P355QH, P355QL1 and P355QL2 variants covering elevated- and low-temperature duty. Default values are 400 MPa yield, 560 MPa tensile, 26 % elongation, about 175 HB and a maximum service temperature of 400 °C. CEV ≤ 0.45 keeps preheat modest; step up to P460QL2 when thinner walls are needed. P355Q has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). P355Q has a yield strength of 400 MPa (58 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 60% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi).
What is P355Q used for?
- pressure vessels
- boilers
- storage tanks
Advantages
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
- Readily welded — 82/100, better than 81% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
P355Q properties
Typical room-temperature values for P355Q-QT; bars are the position among steel grades.
Physical3
P355Q has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
P355Q has a yield strength of 400 MPa (58 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 60% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
P355Q is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
P355Q conducts electricity at 8.2 % IACS, better than 61% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of P355Q takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 25%.
Manufacturability8
P355Q's machinability is good (58/100, better than 75% of steel grades); weldability very good (82/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. P355Q is highlighted; hover a dot for its name, or open the interactive family chart.
Working with P355Q
Is P355Q easy to machine?
Machines like a 175 HB Q&T low-alloy steel — carbide inserts, 120–180 m/min, rigid setups; avoid overheating that would locally temper the plate.
Can P355Q be welded?
Good weldability at CEV ≤ 0.45: use low-hydrogen consumables (matching ~ 460–550 MPa yield), preheat 100–150 °C for thick sections, control interpass ≤ 250 °C and limit heat input to preserve HAZ toughness.
Can P355Q be formed, bent or molded?
Cold form with bend radius ≥ 2–3 t across the rolling direction; hot forming above about 580 °C degrades the Q&T condition and requires re-quench-and-temper.
P355Q 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 | ≤ 0.16 | 0.14 |
| Si | ≤ 0.4 | 0.3 |
| Mn | 0.8 – 1.7 | 1.35 |
| P≤0.020 for QL1, ≤0.020 for QL2 | ≤ 0.03 | 0.01 |
| S≤0.010 / ≤0.005 for QL grades | ≤ 0.02 | 0 |
| Altotal Al, grain refining | ≥ 0.02 | 0.04 |
| Cr | ≤ 0.5 | 0.25 |
| Mo | ≤ 0.5 | 0.2 |
| Ni | ≤ 0.5 | 0.25 |
| Cu | ≤ 0.3 | 0.1 |
| Nb | ≤ 0.05 | 0.02 |
| Ti | ≤ 0.05 | 0.02 |
| V | ≤ 0.08 | 0.03 |
| Zr | ≤ 0.05 | |
| N | ≤ 0.02 | 0.01 |
| B | ≤ 5×10⁻⁴ | |
| Fe | balance |
What surface finishes work on P355Q?
No anodizing; shot-blast then epoxy/zinc-rich primer, metallize or weld-overlay clad for corrosive duty — bare surfaces rust rapidly.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel P355Q in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.886610028-6
How much does P355Q cost?
P355Q is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
P355Q — frequently asked
What is P355Q used for?
P355Q is typically used for pressure vessels, boilers and storage tanks. In short: base Q&T vessel grade; 355 MPa class, easily welded; wide condition and variant range.
What is the yield strength of P355Q?
P355Q has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is P355Q easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like a 175 HB Q&T low-alloy steel — carbide inserts, 120–180 m/min, rigid setups; avoid overheating that would locally temper the plate.
Can P355Q be welded?
Yes — weldability is rated very good (82/100). Good weldability at CEV ≤ 0.45: use low-hydrogen consumables (matching ~ 460–550 MPa yield), preheat 100–150 °C for thick sections, control interpass ≤ 250 °C and limit heat input to preserve HAZ toughness.
What surface finishes work on P355Q?
No anodizing; shot-blast then epoxy/zinc-rich primer, metallize or weld-overlay clad for corrosive duty — bare surfaces rust rapidly.
Can P355Q be formed, bent or molded?
Cold form with bend radius ≥ 2–3 t across the rolling direction; hot forming above about 580 °C degrades the Q&T condition and requires re-quench-and-temper.
What is the maximum service temperature of P355Q?
P355Q 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.
What is the difference between P355Q-QT and P355QL2?
QT is the default condition — standard stocked condition for pressure-vessel plate up to 50 mm; full 355 MPa yield class. P355QL2: cleanest chemistry of the family (low P/S) for LPG/ammonia and Arctic vessels down to −60 °C. Yield strength is 400 MPa in QT versus 405 MPa in P355QL2.
How much does P355Q cost?
P355Q is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- EN 10028-6: Flat products made of steels for pressure purposes — Part 6: Weldable fine grain steels, quenched and tempered — CEN (2017)
- EN 10027-2 Steel numbers (1.8866 P355Q) — CEN (2015)
- EN 13445-3 Unfired pressure vessels — Design (physical property data) — CEN (2021)
- 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)
- Quenched and tempered pressure vessel plate datasheets (Dillinger, voestalpine, SSAB) — Producers (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.