The differences between SA516Gr70 steel and Q345R steel

SA516Gr70(ASME SA516 Grade 70) steel is a carbon steel plate for medium and low temperature pressure vessels, and the implementation standard is ASME SA-516/SA-516M (which is completely equivalent to ASTM standard A516/A516M-10).
Q345R steel belongs to the Chinese standard boiler and pressure vessel steel plate, the implementation standard: GB713-2014.
Both SA516Gr70 steel and Q345R steel are pressure vessel plate. The differences between SA516Gr70 and Q345R has the following points.

1. Comparison of SA516Gr70 and Q345R material manufacturing and delivery status

SA516Gr70 steel manufacturing process is killed steel, and should meet the requirements of A20/A20M standard fine austenite grain size. The thickness less than or equal to 40mm is usually delivered in the state of hot rolling, and the steel plate greater than 40mm must be normalized. Unless otherwise specified by the purchaser, when a notch toughness test is required for a steel plate with a thickness of 40 mm or less, the steel plate should be normalized.
Q345R steel manufacturing process is smelted by oxygen converter or electric furnace, and should be refined outside the furnace, usually delivered in hot rolling, controlled rolling, normalizing state.
By comparison, SA516Gr70 steel material manufacturing and delivery status are stricter.

2. Comparison of chemical composition of SA516Gr70 and Q345R steel (mass fraction)/%

SA516Gr70 steel composition requirements:
Carbon (plate thickness less than or equal to 12.5mm) content ≤ 0.27%
Carbon (plate thickness between 12.5mm -50mm) ≤0.28%
Carbon (thickness between 50mm and 100mm) ≤0.30%
Carbon (thickness greater than 100mm) content ≤0.31%
Manganese content 0.85-1.20
Phosphorus content ≤0.025%
Sulfur content ≤0.025%
Silicon content 0.15--0.40
Note: For each decrease of 0.01% below the specified maximum carbon content, the upper limit of the specified maximum manganese content can be increased by 0.06%, the maximum allowable smelting analysis is 1.5%, and the maximum allowable product analysis is 1.6%.
Q345R steel composition requirements:
C: ≤0.20, Si: ≤0.55, Mn: 1.20-1.70, P: ≤0.025, S: ≤0.010, Cu: ≤0.30, Ni: ≤0.30, Cr: ≤0.30, Mo: ≤0.08, Nb: ≤0.050 , V: ≤0.050, Ti: ≤0.030, Alt: ≥0.020, other Cu+Ni+Cr+Mo≤0.70
By comparing the chemical composition, the chemical composition of the two has a common area, but Q345R has requirements for trace elements, and lower control of harmful elements of sulfur and phosphorus.

3. Comparison of mechanical properties between SA516Gr70 and Q345R steel

Comparing the tensile properties of SA516Gr70 steel and Q345R, it can be seen that Q345R is higher than SA516Gr70, but the Charpy impact temperature of SA516Gr70 is lower, indicating that SA516Gr70 can be used in an environment of minus 46 degrees, and Q345R is not. Q345R is specified in national standard 713 Can do a Charpy minus 20 degrees impact. Q345R produces impact plates of minus 40 degrees in individual domestic steel mills, but no industry recognition has been formed.

It can be seen from the above comparison that Q345R cannot replace SA516Gr70 steel, which is that the specifications of the two standards cannot be the same. SA516Gr70 is tested according to ASME boiler and pressure vessel specifications, and Q345R is tested according to the national standard.

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