Steel P690QL2-QT (Quenched and tempered)
Heat-treated state · default condition
EN 1.8888
Standard as-delivered condition for plate up to 50 mm; full 690 MPa yield with -60 °C impact guarantee.
Values for the QT condition
Other P690QL2 tempers and conditions
P690QL2 is listed in 4 conditions; see the grade overview at P690QL2.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
QT | Extra-heavy section band; choose when wall thickness governs and reduced minimum properties are acceptable. | 690 | 790 | 18 | 21 HRC | 6.9 % IACS |
QT | Heavy plate thickness band with slightly reduced guaranteed strength due to lower through-thickness quench rate. | 710 | 830 | 18 | 23 HRC | 6.9 % IACS |
quenched, tempered and stress relieved (PWHT simulated) | Ordered when the fabricated vessel will see post-weld heat treatment; properties certified after simulated PWHT, typically 10–40 MPa lower strength. | 720 | 820 | 19 | 23 HRC | 6.9 % IACS |
QTDefaultThis page Quenched and tempered | Standard as-delivered condition for plate up to 50 mm; full 690 MPa yield with -60 °C impact guarantee. | 750 | 840 | 18 | 25 HRC | — |
What is P690QL2-QT?
P690QL2-QT is P690QL2 heat treated to QT — standard as-delivered condition for plate up to 50 mm; full 690 MPa yield with -60 °C impact guarantee. P690QL2-QT has a yield strength of 750 MPa (109 ksi) and a tensile strength of 840 MPa (122 ksi) — stronger than 84% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi). P690QL2-QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,430°C (2,606 °F).
Advantages
- Tough — resists crack growth — 130 MPa·√m (118.3 ksi·√in), better than 89% of steel grades
- High strength — 750 MPa (109 ksi), better than 84% of steel grades
Limitations
- Difficult to machine — 35/100, worse than 84% of steel grades
P690QL2-QT properties
Typical room-temperature values for P690QL2-QT; 11 are specific to this condition. Other listed values are P690QL2 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
P690QL2-QT has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,430°C (2,606 °F).
Mechanical16
P690QL2-QT has a yield strength of 750 MPa (109 ksi) and a tensile strength of 840 MPa (122 ksi) — stronger than 84% of steel grades. Elongation at break is 18% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
P690QL2-QT is rated for continuous service to 400°C (752 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 69% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical2
P690QL2-QT has an electrical resistivity of 2.5×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of P690QL2-QT takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability6
P690QL2-QT's machinability is fair (35/100, worse than 84% of steel grades); weldability good (60/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with P690QL2-QT
Is P690QL2 easy to machine?
Machine as a 250 HB Q&T alloy steel: rigid setups, coated carbide, moderate speeds (~80–120 m/min) and positive feed to stay under the work-hardened skin.
Can P690QL2 be welded?
Weldable with low-hydrogen consumables only; CEV ≈ 0.6–0.7 requires preheat/interpass typically 100–175 °C, controlled heat input (≈1.0–2.5 kJ/mm) and matching 690 MPa filler to preserve -60 °C toughness.
Can P690QL2 be formed, bent or molded?
Cold bend with generous radii (about 3× thickness transverse to rolling) and avoid flame-straightening above the tempering temperature, which permanently softens the plate.
What surface finishes work on P690QL2?
No corrosion resistance in bare form — shot blast to Sa 2½ then epoxy/zinc-rich primer or metallize; avoid uncontrolled electroplating because of hydrogen embrittlement risk at this strength level.
P690QL2 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 | ≤ 0.2 | 0.16 |
| Si | ≤ 0.8 | 0.3 |
| Mn | 0.4 – 1.7 | 1.2 |
| P | ≤ 0.02 | 0.01 |
| S | ≤ 0.01 | 0 |
| Nimain contributor to low-temperature toughness | ≤ 2.5 | 1.5 |
| Cr | ≤ 1.5 | 0.5 |
| Mo | ≤ 0.7 | 0.45 |
| Cu | ≤ 0.5 | 0.2 |
| V | ≤ 0.12 | 0.04 |
| Nb | ≤ 0.06 | 0.02 |
| Ti | ≤ 0.05 | 0.02 |
| Zr | ≤ 0.05 | — |
| Bhardenability booster | ≤ 0.01 | 0 |
| N | ≤ 0.02 | 0.01 |
| Altotal Al, for grain refinement | ≥ 0.02 | 0.04 |
| Fe | balance | — |
P690QL2-QT — frequently asked
What is P690QL2-QT used for?
P690QL2-QT is typically used for arctic and offshore structures, mobile crane components, pressure vessels and heavy-duty structural steelwork. In short: −60 °C impact toughness; toughest P690 variant; 690 MPa arctic-grade plate.
What is the yield strength of P690QL2-QT?
P690QL2-QT has a typical yield strength of 750 MPa (109 ksi) and a tensile strength of 840 MPa (122 ksi) — stronger than 84% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is P690QL2-QT easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% of steel grades). Machine as a 250 HB Q&T alloy steel: rigid setups, coated carbide, moderate speeds (~80–120 m/min) and positive feed to stay under the work-hardened skin.
Can P690QL2-QT be welded?
Yes — weldability is rated good (60/100). Weldable with low-hydrogen consumables only; CEV ≈ 0.6–0.7 requires preheat/interpass typically 100–175 °C, controlled heat input (≈1.0–2.5 kJ/mm) and matching 690 MPa filler to preserve -60 °C toughness.
What surface finishes work on P690QL2-QT?
No corrosion resistance in bare form — shot blast to Sa 2½ then epoxy/zinc-rich primer or metallize; avoid uncontrolled electroplating because of hydrogen embrittlement risk at this strength level.
Can P690QL2-QT be formed, bent or molded?
Cold bend with generous radii (about 3× thickness transverse to rolling) and avoid flame-straightening above the tempering temperature, which permanently softens the plate.
What is the maximum service temperature of P690QL2-QT?
P690QL2-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 10027-2 — Material number 1.8888 — CEN (2015)
- EN 1011-2 — Welding recommendations for ferritic steels — CEN (2001)
- 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 690 MPa pressure-vessel plate datasheets (Dillinger / SSAB / thyssenkrupp) — various mills (2023)
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.