Q345D steel: Chemical composition, Mechanical properties

Q345D steel is a low alloy steel plate. The grade of steel consists of three parts: the Chinese pinyin letter representing the yield strength, the value of the yield strength, and the quality grade symbol, for example: Q345D.

Q—the first letter of the Chinese pinyin of the word "Qu" for the yield strength of steel;

345—yield strength value, unit MPa;

D—The quality grade is D grade (grades are divided into A, B, C, D, E).

When the purchaser requires the steel plate to have the performance in the thickness direction, then add a symbol representing the performance level in the thickness direction (Z direction) after the above-mentioned grade, for example: Q345DZ15.

Implementation standard: GB/T1591 (GB/T3274).

Chemical composition of Q345D steel

Carbon C: ≤0.18;

Silicon Si: ≤0.50;

Manganese Mn: ≤1.70;

P: ≤0.030;

S: ≤0.025;

Nb: ≤0.07;

V: ≤0.15;

Titanium Ti: ≤0.20;

Chromium Cr: ≤0.30;

Nickel Ni: ≤0.50;

Copper Cu: ≤0.30;

N: ≤0.012;

Molybdenum Mo: ≤0.10;

Al: ≥ 0.015.

Mechanical properties of Q345D steel

Yield: ≤16mm: ≥345; 16-40mm: ≥335; 40-63mm: ≥325; 63-80mm: ≥315;

80-100mm: ≥305; 100-150mm: ≥285; 150-200mm: ≥275; 200-250: ≥275;250—400: ≥265.

Tensile strength: 450-630.

Elongation: ≥21.

Impact test: -20°C: ≥34.

Smelting method of Q345D steel

Q345D steel is smelted by converter or electric furnace, and refined outside the furnace if necessary.

Delivery status of Q345D steel

Q345D steel are delivered in the state of hot rolling, controlled rolling, normalizing, normalizing + tempering, and thermomechanical rolling (TMCP).

Q345D steel is a low alloy plate commonly used in Chinese. It is the same grade as Germany's S355J2 and American ASTM A529MGr50, with slightly different chemical composition and the same mechanical properties.

Under normalized delivery conditions, it is the same as the German S355J2G3, and even almost the same as the S355J2G4 in performance.

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