What is the Carbon Equivalent (CEV) of P690Q?
The maximum carbon equivalent (CEV) of P690Q steel depends on the plate thickness but is typically a maximum of 0.57% to 0.58%. The specific value for a given plate can be calculated using its exact chemical composition.
P690Q is a weldable, fine-grain structural steel intended for pressure-bearing equipment. It is produced through a rigorous Quenching and Tempering (Q+T) process to achieve an elite balance of high strength and ductility. Governed by the EN 10028-6 standard, it is an essential material for engineers designing equipment that must contain extreme internal pressures while maintaining strict safety margins.
Key Characteristics: The material provides a minimum yield strength of 690 MPa and a tensile strength ranging from 770 to 940 MPa. It features a minimum elongation of 14% and impact energy absorption of at least 40 J at -20°. Its fine-grained microstructure is stabilized with micro-alloying elements to prevent brittle fracture.
Decoding the Name:
P: Steels for pressure purposes.
690: Minimum yield strength (690MPa).
Q: Quenched and tempered delivery condition.
Comparison: Compared to P355GH (yield 355MP), P690Q offers nearly double the strength. This allows for a reduction in plate thickness of approximately 40%-50%, leading to significantly lighter vessels and a reduction in welding filler consumption by nearly 30%.
Application:
Construction of high-pressure storage tanks for liquefied petroleum gas (LPG).
Fabrication of spherical gas holders for industrial storage.
What industries commonly use P690Q?
Industries using P690Q include construction, energy, offshore engineering, mining, heavy equipment manufacturing, and pressure vessel fabrication. Its high strength-to-weight ratio makes it attractive for projects demanding efficiency, safety, and long service life.
Is P690Q corrosion resistant?
P690Q is not inherently corrosion resistant like stainless steel. It requires appropriate surface protection such as painting, coating, or galvanizing depending on the environment. Corrosion resistance depends mainly on external protection and maintenance, not the base material itself.
Why choose P690Q over lower-strength steels?
P690Q is chosen when high load capacity, weight reduction, and structural efficiency are critical. Although it is more expensive and demanding to fabricate, its superior mechanical performance can lead to overall cost savings and improved safety in demanding applications
Chemical composition % of steel P690Q (1.8879): EN 10028-6-2009
| According EN 10216-3:2014: 1.2=< Mn=<1.7; 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 0.025 | max 0.01 | 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 P690Q (1.8879)
| 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) | -20° 27 |
0° 31-40 |
+20° 35-60 |
| KV - Impact energy (J) longitud., (+QT) | -10° 40 |
0° 45 |
+20° 50 |
| A - Min. elongation at fracture (%) (+QT) | 14-16 |
1. What is P690Q steel?
P690Q is a high-strength structural steel defined in EN 10025-6. The "P" indicates pressure purposes, "690" refers to the minimum yield strength in MPa, and "Q" means quenched and tempered. It is designed for heavy-duty applications requiring high strength, toughness, and good weldability under demanding service conditions.
2. What are the main applications of P690Q?
P690Q is commonly used in pressure vessels, cranes, offshore structures, bridges, heavy machinery, and lifting equipment. Its high yield strength allows for reduced material thickness while maintaining structural integrity. This makes it ideal for applications where weight reduction, load-bearing capacity, and safety are critical.
3. What does the "Q" in P690Q mean?
The letter "Q" indicates that the steel is supplied in the quenched and tempered condition. Quenching increases hardness and strength, while tempering improves toughness and ductility. This heat treatment combination gives P690Q its excellent balance of strength, toughness, and reliability.
4. Is P690Q easy to weld?
P690Q has good weldability for a high-strength steel, but careful welding procedures are required. Preheating, controlled heat input, and appropriate filler materials are recommended to avoid hydrogen-induced cracking. Welding parameters should be selected based on plate thickness, joint design, and service requirements.
5. What impact toughness does P690Q offer?
P690Q provides excellent low-temperature impact toughness. Typical Charpy V-notch requirements are 27 J at –40°C, depending on thickness. This makes it suitable for structures exposed to cold climates or dynamic loading, where resistance to brittle fracture is essential.
6. How does P690Q compare to S690Q?
P690Q and S690Q have similar mechanical properties, but different intended uses. "P" grades are intended for pressure purposes, while "S" grades are for structural applications. Certification, testing, and inspection requirements for P690Q are generally stricter due to pressure-related service conditions.
7. What heat treatment is used for P690Q?
P690Q is heat-treated by quenching and tempering. The steel is heated to austenitizing temperature, rapidly quenched, and then tempered at a controlled temperature. This process produces a fine microstructure that delivers high strength, good toughness, and stable mechanical properties.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff
