Q245R and Q345R are Chinese standard (GB 713) carbon steel plates specifically designed for making boilers and pressure vessels, differing primarily in strength and manganese content; Q245R offers good weldability and suitability for moderate conditions, while Q345R has higher strength (yield strength ≥345 MPa) due to increased manganese, making it better for higher temperature/pressure applications like hydrogen or ammonia service, though both are excellent for critical industrial uses.
Q245R steel plate and Q345R steel plate are two commonly used materials for pressure vessels. For a long time, there have been many misunderstandings in the reasonable selection of these two materials.
Chemical Composition:
Q245R: The chemical composition of Q245R typically includes carbon (C) content up to 0.20%, manganese (Mn) content ranging from 0.40-0.60%, silicon (Si) content up to 0.35%, phosphorus (P) content ≤0.025%, sulfur (S) content ≤0.015%, and trace amounts of other elements.
Q345R: The chemical composition of Q345R typically includes carbon (C) content up to 0.20%, manganese (Mn) content ranging from 0.50-1.60%, silicon (Si) content up to 0.55%, phosphorus (P) content ≤0.025%, sulfur (S) content ≤0.015%, and trace amounts of other elements.
Mechanical Properties:
Q245R: The minimum yield strength of Q245R is 245 MPa (35,500 psi), and the minimum tensile strength is 400-520 MPa (58,000-75,400 psi). The elongation at break is typically around 22%.
Q345R: The minimum yield strength of Q345R is 345 MPa (50,000 psi), and the minimum tensile strength is 510-640 MPa (74,100-92,800 psi). The elongation at break is typically around 21%.
Application:
Q245R: Q245R is primarily used for the fabrication of pressure vessels and boilers that operate at moderate temperatures. It is suitable for applications involving mediums such as liquefied petroleum gas (LPG), natural gas, and crude oil.
Q345R: Q345R is used for the production of pressure vessels and boilers that operate at high temperatures. It is suitable for applications involving mediums with higher operating temperatures, such as hydrogen, ammonia, and methanol.
It's important to consider these differences in composition, mechanical properties, and application when choosing between Q245R and Q345R for a specific pressure vessel or boiler application. It is advisable to consult the relevant standards and specifications, such as GB 713 and GB/T 713, for detailed information and requirements related to these steel grades.
In summary, when selecting Q245R steel plate and Q345R steel plate as pressure vessel materials, the influence of steel chemical composition and medium energy should be fully considered in order to select Q245R steel plate and Q345R steel plate reasonably.
