Q345R is a Chinese standard pressure vessel steel plate, belonging to low-alloy high-strength steel. It is widely used in manufacturing pressure vessels like boilers and storage tanks, with good toughness and weldability to adapt to harsh working conditions.
Q345R plates are called pressure vessel steel plates sometimes. These plates include carbon steel and alloy steel for high/intermediate/low-temperature applications.
Q345R Boiler Quality Steel Plate Chemical Element:
| Element | Min | Max | Similar |
|---|---|---|---|
| V | 0.1500 | 0.3000 | - |
| Cu | - | 0.2500 | - |
| Si | - | 0.5500 | - |
| S | - | 0.0150 | - |
| P | - | 0.0250 | - |
| Mn | 1.2000 | 1.6000 | - |
| C | - | 0.2000 | - |
| Al | 0.0200 | - | - |
| Ni | - | 0.3000 | - |
| Cr+Ni+Cu+Mo | - | 0.7000 | - |
| Cr | - | 0.3000 | - |
| Mo | - | 0.0800 | - |
| Cu | - | 0.3000 | - |
| V | - | 0.0500 | - |
| Ti | - | 0.0300 | - |
| Nb | - | 0.0500 | - |
| S | - | 0.0100 | - |
| Mn | 1.2000 | 1.7000 | - |
| C | - | 0.2000 | - |
| Al | 0.0200 | - | - |
Q345R Pressure Vessel Steel Mechanical Properties:
| Yield Rp0.2 (MPa) |
Tensile Rm (MPa) |
Impact KV/Ku (J) |
Elongation A (%) |
Reduction in cross section on fracture Z (%) |
As-Heat-Treated Condition | Brinell NMness (HBW) |
|---|---|---|---|---|---|---|
| 886 (≥) | 259 (≥) | 21 | 12 | 43 | Solution and Aging, Annealing, Ausaging, Q+T,etc | 131 |
Q345R PVQ Steel Plate Physical Properties:
| Temperature (°C) |
Modulus of elasticity (GPa) |
Mean coefficient of thermal expansion 10-6/(°C) between 20(°C) and | Thermal conductivity (W/m·°C) |
Specific thermal capacity (J/kg·°C) |
Specific electrical resistivity (Ω mm²/m) |
Density (kg/dm³) |
Poisson's coefficient, ν |
|---|---|---|---|---|---|---|---|
| 41 | - | - | 0.31 | - | |||
| 223 | 459 | - | 22.3 | 332 | - | ||
| 853 | - | 32 | 41.2 | 224 | 412 |
advantages
Excellent Mechanical Properties: It has high yield strength and tensile strength, matching good toughness. This balance ensures it can bear medium pressure and load stably in harsh working conditions, avoiding deformation or fracture.
Good Weldability and Formability: It is easy to weld with common processes (manual arc welding, etc.) without obvious defects. It also adapts well to rolling, bending and stamping, facilitating the manufacturing of various pressure vessel components.
High Purity and Corrosion Resistance: Advanced smelting processes reduce impurities like sulfur and phosphorus. It has good resistance to neutral and weakly corrosive media, extending service life in petrochemical and thermal power applications.
Cost-Effective and Wide Adaptability: Compared with high-alloy steels, it has lower production costs. It works stably in -20℃ to 475℃, suitable for multiple industries such as metallurgy, municipal engineering and nuclear power auxiliary equipment.
Processes Adopted for Q345R
Smelting Process: Adopts converter/electric furnace smelting, combined with LF refining and RH vacuum degassing. It effectively removes sulfur, phosphorus and other impurities, optimizes chemical composition, and ensures steel purity.
Forming Process: Mainly includes hot rolling, cold bending and stamping. Hot rolling guarantees uniform thickness and mechanical properties; forming parameters are strictly controlled to avoid cracks.
Welding Process: Applies manual arc welding, submerged arc welding, etc. Matched welding materials are used, with preheating and post-weld heat treatment to eliminate stress.
Inspection Process: Conducts non-destructive testing (ultrasonic, radiographic) after welding, and inspects mechanical properties and chemical composition to ensure no defects.
Key Considerations for Substitution
When substituting Q345R with an equivalent like ASME SA516 Gr. 70, you must verify:
Impact Testing: Ensure the V-notch impact energy meets the specific design temperature requirements.
Delivery State: Confirm whether the plate needs to be Normalized (standard for Q345R) or as-rolled.
Thickness Correction: Yield strength values may differ slightly as plate thickness increases across different standards.
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What standard does Q345R comply with?
Q345R complies with the Chinese national standard GB/T 713-2014. This standard specifies the technical requirements, test methods, inspection rules and other details for carbon and alloy steel plates for pressure vessels.
What is the impact toughness requirement of Q345R?
Q345R requires a certain impact toughness at room temperature or low temperature (usually -20℃). The average impact energy is not less than 34 J, ensuring it does not break brittlely under impact load.
Can Q345R be used at low temperatures?
Q345R can be used at low temperatures appropriately, generally down to -20℃. For lower temperature environments, it needs to pass strict low-temperature impact tests to confirm its toughness meets the requirements.
How to inspect the quality of Q345R steel plates?
Quality inspection of Q345R includes chemical composition analysis, mechanical property testing (tensile, yield, impact), ultrasonic flaw detection, surface quality inspection, etc., to ensure it meets standard requirements.
What is the density of Q345R?
The density of Q345R is about 7.85 g/cm³, the same as ordinary carbon steel. This density value is widely used in weight calculation and structural design of pressure vessels and related components.
What heat treatment is Q345R usually subjected to?
Q345R is usually subjected to normalizing heat treatment. This process refines the grain structure, improves the steel's toughness and strength, and ensures the stability of its mechanical properties.
What is the minimum yield strength of Q345R?
The minimum yield strength of Q345R is 345 MPa (megapascals), which is the key index that defines its grade. This strength ensures it can withstand high pressure and load in pressure vessel applications.
What is the application scope of Q345R?
Q345R is mainly used to make pressure vessels such as boilers, steam drums, liquefied gas tanks, and chemical reactors. It is suitable for working environments with medium and low temperature and high pressure.
Is Q345R weldable?
Yes, Q345R has excellent weldability. It can be welded by common methods like manual arc welding, gas metal arc welding and submerged arc welding without special preheating.
What is the tensile strength range of Q345R?
The tensile strength of Q345R ranges from 470 MPa to 630 MPa. This range reflects the steel's ability to resist breaking under tension, making it suitable for pressure-bearing structures.