P690QL1 is a high-yield, quenched and tempered (Q+T) fine-grain steel grade used for pressure purposes, complying with the EN 10028-6 standard.
Designation Breakdown
P: Steel for Pressure purposes.
690: Minimum yield strength of 690 MPa (for thickness ≤50mm).
Q: Quenched and Tempered delivery condition.
L1: Low-temperature quality, tested for impact energy at -40°C.
Steel Number: 1.8881.
Chemical composition % of steel P690QL1 (1.8881): EN 10028-9-2003
| According EN 10216-3:2014: 1.2=< Mn=<1.7; P=<0.025; S=<0.015; Al=<0.02; |
| C | Si | Mn | Ni | P | S | Cr | Mo | V | N | Nb | Ti | Cu | Zr | B |
| max 0.2 | max 0.8 | max 1.7 | max 2.5 | max 0.02 | max 0.008 | max 1.5 | max 0.7 | max 0.12 | max 0.015 | max 0.06 | max 0.05 | max 0.3 | max 0.15 | max 0.005 |
Mechanical properties of steel P690QL1 (1.8881)
| Nominal thickness (mm): | to 100 | 100 - 150 |
| Rm - Tensile strength (MPa) (+QT) | 770-940 | 720-900 |
| Nominal thickness (mm): | to 50 | 50 - 100 | 100 - 150 |
| ReH - Minimum yield strength (MPa) (+QT) | 690 | 670 | 630 |
| Nominal thickness(mm): | to 20 | 20 - 40 | 40 - 50 | 50 - 65 | 65 - 80 | 80 - 100 |
| Rp0.2 0.2% proof strength (MPa) (+QT) | 690 | 650 | 615 | 580 | 540 | 500 |
| KV - Impact energy (J) transverse, (+QT) | -40° 27 |
-20° 31-40 |
0° 39-60 |
+20° 43 |
| KV - Impact energy (J) longitud., (+QT) | -30° 40 |
-20° 47 |
-10° 53 |
0° 60 |
+20° 65 |
| A - Min. elongation at fracture (%) (+QT) | 14-16 |
Typical Applications
This steel is designed for high-stress environments where weight reduction and safety are critical:
Pressure Vessels: Large-scale storage tanks for gases or liquids.
Boilers: High-pressure industrial boiler components.
Power Generation: Penstocks for hydroelectric power stations and nuclear reactor components.
Chemical Industry: High-pressure reactors and heat exchangers.
Technical Considerations
Weldability: While weldable, the high strength requires strict control of the welding process.
Preheating (typically 130°C–150°C) is often necessary to prevent cold cracking.
Heat Treatment: Delivered in the Quenched and Tempered state. Subsequent hot forming or Post-Weld Heat Treatment (PWHT) must be carefully controlled to avoid reducing the mechanical properties.
Contact us at beam@gneesteelgroup.com for pricing, technical support, or customized solutions. We are always ready to support your project.
What is the service temperature range of P690QL1?
The service temperature range of P690QL1 is generally -20℃ to 500℃. Beyond this range, its mechanical properties may decline, so it should be used within the specified temperature range in engineering applications.
What is the difference between P690QL1 and Q690 steel?
P690QL1 is a European standard steel (EN 10025-6), while Q690 is a Chinese standard steel (GB/T 1591). The former has stricter low-temperature impact toughness requirements, and the chemical composition and test methods also differ slightly.
Is P690QL1 a quenched and tempered steel?
Yes, P690QL1 is a quenched and tempered high-strength steel. Quenching (rapid cooling after heating to austenitizing temperature) and tempering (heating to a certain temperature and cooling) give it excellent strength and toughness matching.
What is the maximum thickness of P690QL1 plates?
The maximum thickness of P690QL1 plates can reach 150 mm (depending on manufacturers). Thick plates need strict heat treatment control to ensure uniform mechanical properties throughout the thickness.
How to store P690QL1 materials?
P690QL1 should be stored in a dry, well-ventilated warehouse to avoid moisture and rust. It should be placed away from corrosive substances and stacked neatly to prevent deformation and damage.
What machining methods are suitable for P690QL1?
P690QL1 is suitable for turning, milling, drilling, grinding and other machining methods. High-speed steel or cemented carbide tools should be used, and proper cutting parameters should be set to ensure machining efficiency and surface quality.
Can P690QL1 be used to make pressure vessels?
Yes, P690QL1 can be used to make medium and low pressure vessels. Its high strength and good toughness can meet the pressure-bearing requirements of vessels, but it needs to pass strict quality inspection and certification.
Can P690QL1 be used in offshore engineering?
Yes, P690QL1 is widely used in offshore engineering. Its high strength, excellent impact toughness and corrosion resistance can withstand harsh marine environments (high humidity, salt spray, wind and wave loads).
What is the preheating temperature for P690QL1 welding?
The preheating temperature for P690QL1 welding is usually 80-150℃. Preheating can reduce the temperature gradient of the weld zone, prevent cold cracks, and improve the quality of the weld joint.
What is the surface quality requirement of P690QL1?
The surface of P690QL1 should be free of cracks, folds, scars, delaminations and other defects. Minor surface defects can be repaired by grinding, but the thickness after repair should not be less than the minimum allowable value.