Q420A low alloy high strength steel

Implement the standard GB1591-2008.

It consists of Q+number+quality grade symbol+deoxygenation method symbol.
Its steel number is prefixed with "Q", which represents the yield point of the steel, and the following number represents the yield point value in MPa. For example, Q420 represents a structural steel with a yield stress (σs) of 420 MPa.

The quality grades are A, B, C, D, and E. The A grades are of poorer quality and the E grades are of the highest quality. They are:
Q420A grade is not required for impact toughness test;
Q420B grade is for impact toughness test at room temperature (20℃);
Q420C grade is used for 0 ℃ impact toughness test;
Q420D grade is for -20℃ impact toughness test; Q420E is for -40℃ impact toughness test. Charpy V-notch specimens were used for the impact toughness test.

Chemical composition of Q420:
C≤0.20;
Si ≤0.50;
Mn ≤1.70;
P≤0.035;
S≤0.035;
Nb≤0.07;
V≤0.20;
Ti≤0.20;
Cr≤0.30;
Ni≤0.80;
Cu≤0.30;
N≤0.015;
Mo≤0.20

Mechanical properties of Q420:
Yield strength: ≥340
Tensile strength: 500-680
Elongation after break:≥18
Impact energy: 34

Q420 has good mechanical properties and weldability, and good cold and hot workability. Due to the addition of Wei alloying elements, the strength and toughness of steel are improved and improved.

Q420 is mainly used in the manufacture of mining machinery, heavy vehicles, ships, bridges, medium and high pressure boilers, vessels and other large welding and structural parts.

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