Steel P355QL2-QT (Quenched and tempered)
Heat-treated state · default condition
EN 1.8869
Standard supply condition for plate up to 50 mm; full 355 MPa minimum yield and -60 °C impact guarantee.
Values for the QT condition
Other P355QL2 tempers and conditions
P355QL2 is listed in 4 conditions; see the grade overview at P355QL2.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Q+T | Thickest standard section; lowest guaranteed strength and the most demanding hardenability case. | 380 | 520 | 25 | 155 HB | 7.8 % IACS |
Q+T | Heavy plate condition; same heat treatment with slightly reduced guaranteed yield due to section size. | 400 | 540 | 25 | 160 HB | 7.8 % IACS |
Q+T + stress relieved / simulated PWHT | Ordered when the vessel will receive post-weld heat treatment; properties are certified after a simulated PWHT cycle (typ. 530–580 °C). | 400 | 535 | 27 | 158 HB | 7.8 % IACS |
QTDefaultThis page Quenched and tempered | Standard supply condition for plate up to 50 mm; full 355 MPa minimum yield and -60 °C impact guarantee. | 420 | 550 | 26 | 165 HB | 7.8 % IACS |
What is P355QL2-QT?
P355QL2-QT is P355QL2 heat treated to QT — standard supply condition for plate up to 50 mm; full 355 MPa minimum yield and -60 °C impact guarantee. P355QL2-QT has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 53% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi). P355QL2-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).
Advantages
- Tough — resists crack growth — 150 MPa·√m (136.5 ksi·√in), better than 96% 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
- Forms and bends easily — 65/100, better than 81% of steel grades
P355QL2-QT properties
Typical room-temperature values for P355QL2-QT; 23 are specific to this condition. Other listed values are P355QL2 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
P355QL2-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
P355QL2-QT has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 53% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
P355QL2-QT 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
P355QL2-QT 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 P355QL2-QT takes about 27 MJ of energy and emits 2.1 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 20%.
Manufacturability7
P355QL2-QT's machinability is good (58/100, better than 75% of steel grades); weldability very good (82/100); formability good (65/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with P355QL2-QT
Is P355QL2 easy to machine?
Machines like a medium-strength Q&T C-Mn steel at ~60 % of AISI 1212; use rigid setups, coated carbide and moderate speeds — avoid heavy grinding heat that could locally over-temper.
Can P355QL2 be welded?
Very good weldability (CEV typically ≤0.45); use low-hydrogen consumables matched for -60 °C CVN, preheat by thickness/CEV and cap heat input to keep the HAZ toughness the QL2 grade is bought for.
Can P355QL2 be formed, bent or molded?
Cold form with generous bend radii (≥2.5–3 t) transverse to rolling; hot forming above ~580 °C destroys the Q&T condition and requires re-quench-and-temper.
What surface finishes work on P355QL2?
Not corrosion-resistant bare — shot blast to Sa 2½ and apply epoxy/zinc-rich primer, metallising or hot-dip galvanising; anodising is not applicable.
P355QL2 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 | 0.13 |
| Si | ≤ 0.5 | 0.35 |
| Mn | 0.9 – 1.7 | 1.35 |
| P | ≤ 0.02 | 0.01 |
| Slow S for -60 °C toughness | ≤ 0.01 | 0 |
| Altotal Al, grain refinement | ≥ 0.02 | 0.04 |
| N | ≤ 0.02 | 0.01 |
| Cr | ≤ 0.3 | 0.15 |
| Niraises low-temperature toughness | ≤ 0.5 | 0.25 |
| Cu | ≤ 0.3 | 0.15 |
| Mo | ≤ 0.25 | 0.1 |
| Nbmicroalloying | ≤ 0.05 | 0.03 |
| Ti | ≤ 0.03 | 0.02 |
| V | ≤ 0.05 | 0.02 |
| Bhardenability, heavy sections | ≤ 0.01 | 0 |
| Zr | ≤ 0.05 | — |
| Fe | balance | — |
P355QL2-QT — frequently asked
What is P355QL2-QT used for?
P355QL2-QT is typically used for cryogenic pressure vessels, arctic service tanks, boilers and low-temperature piping. In short: toughness to -60 °C; best-weldability pressure plate; Z35 through-thickness quality.
What is the yield strength of P355QL2-QT?
P355QL2-QT has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 53% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is P355QL2-QT easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like a medium-strength Q&T C-Mn steel at ~60 % of AISI 1212; use rigid setups, coated carbide and moderate speeds — avoid heavy grinding heat that could locally over-temper.
Can P355QL2-QT be welded?
Yes — weldability is rated very good (82/100). Very good weldability (CEV typically ≤0.45); use low-hydrogen consumables matched for -60 °C CVN, preheat by thickness/CEV and cap heat input to keep the HAZ toughness the QL2 grade is bought for.
What surface finishes work on P355QL2-QT?
Not corrosion-resistant bare — shot blast to Sa 2½ and apply epoxy/zinc-rich primer, metallising or hot-dip galvanising; anodising is not applicable.
Can P355QL2-QT be formed, bent or molded?
Cold form with generous bend radii (≥2.5–3 t) transverse to rolling; hot forming above ~580 °C destroys the Q&T condition and requires re-quench-and-temper.
What is the maximum service temperature of P355QL2-QT?
P355QL2-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 10028-6 — Flat products for pressure purposes, Part 6: Weldable fine grain steels, quenched and tempered — CEN (2017)
- EN 10164 — Steel products with improved deformation properties perpendicular to the surface — CEN (2018)
- 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 (P355QL1/QL2) datasheets — Dillinger / thyssenkrupp Steel (2022)
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.