P460QL1 is a quenched and tempered alloy structural steel, mainly applied in the fabrication of low-temperature pressure vessels and boilers. It features excellent low-temperature toughness, high strength, and superior weldability, which ensures stable and reliable performance even under harsh operating conditions.
Key Technical Specifications
Standard: EN 10028-6 (Flat products made of steels for pressure purposes – Part 6: Weldable fine grain steels, quenched and tempered).
Material Number: 1.8872.
Delivery Condition: Quenched and Tempered (Q+T) to ensure high strength and excellent low-temperature toughness.
Nomenclature Breakdown
P: Indicates "Pressure" purposes (vessels/boilers).
460: Represents the minimum yield strength of 460 MPa (for thicknesses ≤ 50mm).
Q: Stands for "Quenched and Tempered" heat treatment.
L1: Specifies the low-temperature impact test quality. It must meet a minimum impact energy of 27 Joules at -40°C.
P460QL1 Pressure Vessel Plate Material Chemical Composition:
| C | Si | Mn | P | S | B | N | Cr |
| 0.18 | 0.50 | 1.70 | 0.020 | 0.010 | 0.005 | 0.015 | 0.50 |
| Cu | Mo | Nb | Ni | Ti | V | Zr | |
| 0.30 | 0.50 | 0.05 | 1.00 | 0.03 | 0.08 | 0.05 | |
P460QL1 PVQ Steel Plate Mechanical Properties:
| Thickness (mm) | ≤ 50 | > 50 ≤ 100 | > 100 |
| Yield strength (≥Mpa) | 460 | 440 | 400 |
| Thickness (mm) | ≤ 100 | > 100 | |
| Tensile strength (Mpa) | 550-720 | 500-670 | |
Processes adopted for P460QL1
Quenching and tempering (Q&T): P460QL1 is supplied in the quenched and tempered condition. Quenching is carried out at a temperature typically between 880°C and 950°C, followed by rapid cooling in water or oil to achieve a fully martensitic or bainitic microstructure. Tempering is then performed at 550°C to 650°C to improve toughness, reduce hardness, and relieve residual stresses, resulting in a fine-grained, high-strength structure.
Thermo-mechanical controlled processing (TMCP): Some producers use TMCP to refine the grain size and enhance mechanical properties. This involves controlled rolling at temperatures below the austenite recrystallization region, followed by accelerated cooling to achieve a uniform, fine microstructure with good strength and toughness.
Clean steelmaking processes: Advanced steelmaking techniques such as basic oxygen furnace (BOF) or electric arc furnace (EAF) with secondary refining (LF, VD, or RH) are employed to reduce impurities like sulfur and phosphorus, control carbon content, and improve purity. This ensures good weldability and resistance to brittle fracture.
Precision rolling: The steel is rolled with strict control over temperature, reduction ratio, and finishing temperature to ensure uniform thickness, good surface quality, and consistent mechanical properties across the plate.
Heat treatment after welding: Post-weld heat treatment (PWHT) is often applied to reduce residual stresses and improve toughness in the heat-affected zone (HAZ). Typical PWHT temperatures range from 550°C to 680°C, depending on plate thickness and welding conditions.
Surface treatment: Shot blasting or pickling is used to remove scale and contaminants, followed by the application of protective coatings such as epoxy or polyurethane paints to enhance corrosion resistance and extend service life.
P460QL1 applications
Pressure vessels and storage tanks: P460QL1 is widely used in the fabrication of pressure vessels, including spherical tanks, cylindrical tanks, and large storage tanks for oil, gas, and chemical products. Its high yield strength and good low-temperature toughness make it suitable for operating conditions with high internal pressure and low ambient temperatures.
Petrochemical and chemical equipment: It is used to manufacture reactors, heat exchangers, separators, and other key equipment in refineries, chemical plants, and gas processing facilities. The steel's excellent weldability and resistance to brittle fracture ensure the reliability and safety of these critical components.
Power industry applications: P460QL1 is applied in the construction of boilers, pressure parts of steam generators, and high-pressure pipelines in thermal power plants and nuclear power plants. It can withstand high temperatures and pressures while maintaining good mechanical properties.
Offshore and marine structures: Due to its good toughness at low temperatures and high strength, P460QL1 is used in offshore platforms, FPSO units, and other marine structures exposed to harsh environments such as low temperatures, high winds, and corrosive seawater.
General heavy engineering: It is also used in heavy machinery, large-diameter pipes, and structural components that require high strength, good weldability, and excellent impact resistance, such as in the construction of bridges, cranes, and mining equipment.
Comparison with Similar Grades
P460QL2: Similar to QL1 but tested at even lower temperatures (-60°C).
S460QL1: A structural steel (EN 10025-6) with the same strength but not certified for pressure vessel use.
ASTM Equivalent: Roughly equivalent to ASTM A517 or A537 Class 2/3 depending on the specific application requirements.
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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.
Does P460QL1 need to be tested for hydrogen induced cracking?
Yes, for P460QL1 used in hydrogen-containing environments or important pressure vessels, hydrogen induced cracking (HIC) testing is usually required to ensure that the material will not crack due to hydrogen absorption during use.
What are the storage requirements for P460QL1 plates?
P460QL1 plates should be stored in a dry, ventilated and rainproof warehouse to avoid moisture and rust. They should be placed horizontally, separated from the ground by sleepers, and avoid collision and scratch on the surface.
Can P460QL1 be used in high-pressure pipelines?
Yes, P460QL1 is suitable for manufacturing high-pressure pipelines. Its high yield strength and good toughness can withstand the high pressure of the medium in the pipeline, and it can adapt to the temperature changes during pipeline operation.
What are the surface quality requirements of P460QL1?
The surface of P460QL1 shall be clean, free of cracks, folds, delaminations, inclusions and other defects. Minor surface defects that do not affect the use can be repaired by grinding, and the depth of repair shall not exceed the allowable deviation of the plate thickness.
What is the maximum working pressure that P460QL1 can bear?
The maximum working pressure depends on the thickness of the material, the working temperature and the structural design of the equipment. Generally, it can bear working pressures above 10 MPa when used in pressure vessels with reasonable design.
What is the difference between P460QL1 and P460Q?
The main difference is the low-temperature toughness level. P460QL1 has higher low-temperature toughness (test temperature -20℃) than P460Q, and is more suitable for low-temperature working environments. Their yield strength and tensile strength are basically the same.
Does P460QL1 have magnetic properties?
Yes, P460QL1 is a ferromagnetic material and has certain magnetic properties. This characteristic should be considered in the design and use of equipment that is sensitive to magnetic fields, such as some precision instruments and equipment.
Can P460QL1 be used to manufacture boilers?
Yes, P460QL1 is a common boiler steel. It can withstand high temperature and high pressure in boiler operation, and its excellent low-temperature toughness can avoid brittle fracture during boiler startup and shutdown at low temperatures.
What is the elongation of P460QL1?
The minimum elongation of P460QL1 is 20% (after tensile test). Good elongation means that the material has good plastic deformation ability, which can absorb energy when subjected to external forces and avoid sudden fracture.
Can P460QL1 be machined?
Yes, P460QL1 has good machinability. It can be processed by turning, milling, drilling, planing and other machining methods, but it is necessary to select appropriate cutting tools and cutting parameters to improve processing efficiency and surface quality.