Steel P355QL1
EN 1.8868
A quenched-and-tempered fine-grain pressure vessel steel with 355 MPa minimum yield strength and guaranteed impact toughness down to -40°C, used for welded pressure equipment operating at low temperatures.
Reference datasheet — P355QL1 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
P355QL1 tempers and conditions
P355QL1 is supplied in 4 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
QT | Thickest standard class for very heavy vessel shells and forged-plate nozzles; lowest guaranteed strength. | 360 | 520 | 24 | 165 HB | 7.8 % IACS |
QT | Heavy plate class — strength de-rated for section size, same -40 °C toughness requirement. | 380 | 540 | 25 | 170 HB | 7.8 % IACS |
quenched, tempered and stress-relieved (simulated PWHT) | Choose when the vessel will see post-weld heat treatment; properties are certified after a simulated PWHT cycle (typically 530–580 °C). | 385 | 545 | 27 | 168 HB | 7.8 % IACS |
QTDefault Quenched and tempered | Standard supply condition for plate up to 50 mm — full 355 MPa yield class with -40 °C impact guarantee. | 400 | 560 | 26 | 175 HB | 7.8 % IACS |
What is P355QL1?
A quenched-and-tempered fine-grain pressure vessel steel with 355 MPa minimum yield strength and guaranteed impact toughness down to -40°C, used for welded pressure equipment operating at low temperatures. P355QL1 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). P355QL1 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 P355QL1 used for?
- Pressure vessels
- Boilers
- Low-temperature storage tanks
- Piping systems
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 — 80/100, better than 79% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
P355QL1 properties
Typical room-temperature values for P355QL1-QT; bars are the position among steel grades.
Physical3
P355QL1 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
P355QL1 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
P355QL1 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
P355QL1 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of P355QL1 takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 25%.
Manufacturability7
P355QL1's machinability is good (55/100, better than 62% of steel grades); weldability very good (80/100); 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. P355QL1 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with P355QL1
Is P355QL1 easy to machine?
Machines like a 400 MPa-yield low-alloy steel — rigid setups, coated carbide at ~120–180 m/min, avoid heavy work hardening on drilled nozzle bores.
Can P355QL1 be welded?
Excellent weldability at low CEV; use low-hydrogen consumables matching 355 MPa class, control preheat (typically 100–150 °C for t > 40 mm) and keep heat input moderate to protect HAZ toughness at -40 °C.
Can P355QL1 be formed, bent or molded?
Cold-form shells and heads with generous bend radii (≥3t); hot forming above the tempering temperature requires re-quenching and tempering to restore certified properties.
P355QL1 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, EN 10028-6 | ≤ 0.16 | 0.13 |
| Si | ≤ 0.5 | 0.3 |
| Mn | 1 – 1.7 | 1.35 |
| P | ≤ 0.02 | 0.01 |
| S | ≤ 0.01 | 0 |
| Altotal Al, grain refinement | ≥ 0.02 | 0.04 |
| Cr | ≤ 0.3 | 0.15 |
| Cu | ≤ 0.3 | 0.1 |
| Mo | ≤ 0.25 | 0.1 |
| Ni | ≤ 0.5 | 0.25 |
| Nb | ≤ 0.05 | 0.02 |
| Ti | ≤ 0.03 | 0.01 |
| V | ≤ 0.05 | 0.02 |
| Zr | ≤ 0.05 | |
| N | ≤ 0.02 | 0.01 |
| B | ≤ 5×10⁻⁴ | |
| Fe | balance |
What surface finishes work on P355QL1?
No anodizing — blast to Sa 2½ and apply epoxy/zinc-rich paint, metallizing or internal cladding for corrosive service.
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 P355QL1 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.8868
How much does P355QL1 cost?
P355QL1 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
P355QL1 — frequently asked
What is P355QL1 used for?
P355QL1 is typically used for pressure vessels, boilers, low-temperature storage tanks and piping systems. In short: weldable -40 °C vessel plate; fine-grain quenched and tempered; low carbon equivalent.
What is the yield strength of P355QL1?
P355QL1 has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is P355QL1 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines like a 400 MPa-yield low-alloy steel — rigid setups, coated carbide at ~120–180 m/min, avoid heavy work hardening on drilled nozzle bores.
Can P355QL1 be welded?
Yes — weldability is rated very good (80/100). Excellent weldability at low CEV; use low-hydrogen consumables matching 355 MPa class, control preheat (typically 100–150 °C for t > 40 mm) and keep heat input moderate to protect HAZ toughness at -40 °C.
What surface finishes work on P355QL1?
No anodizing — blast to Sa 2½ and apply epoxy/zinc-rich paint, metallizing or internal cladding for corrosive service.
Can P355QL1 be formed, bent or molded?
Cold-form shells and heads with generous bend radii (≥3t); hot forming above the tempering temperature requires re-quenching and tempering to restore certified properties.
What is the maximum service temperature of P355QL1?
P355QL1 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does P355QL1 cost?
P355QL1 is a budget-cost steel ($), 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 — Weldable fine grain steels, quenched and tempered — CEN (2017)
- EN 10027-2 Steel numbering (1.8868) — CEN (2015)
- EN 13445-3 Unfired pressure vessels — Design (material physical data) — CEN (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Quenched and tempered pressure vessel plate datasheets (Dillinger / Industeel / voestalpine) — various mills (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.