Comparation Of Q345A,Q345B,Q345C,Q345D,Q345E

Some foreign customers are often confused about GB Q345 steel. Q345 low alloy high strength steel is the replacement steel of old GB grade 12MnV, 14MnNb, 18Nb, 16MnRE, 16Mn, etc. The chemical element is similar to 16Mn, and Q345 increases the micro alloy element V, Ti and Nb which refines the grain, greatly improving the toughness and comprehensive mechanical properties of steel, thus allows a greater thickness. Therefore, the mechanical performance of Q345 steel is better than that of 16Mn steel, especially its low temperature performance.


Q345 series steel includes Q345A, Q345B, Q345C, Q345D and Q345E, where Q represents the yield strength, the latter number 345 represents the yield point value (in MPa), and the letters A,B,C,D and E respectively represent the low-temperature impact resistance of the steel, mainly due to the different impact temperatures. In short, Q345A does not do impact;Q345B, 20 ℃ room temperature impact;Q345C, 0 degree impact; Q345D, -20 degree impact;Q345E, -40 impact. Different impact temperature, impact value is also different. Grade of quality and code name of deoxidization method can be indicated if necessary.

 

CHEMICAL COMPOSITION OF Q345 SERIES STEEL

Materials

C

Si

Mn

P

S

Ni

Cr

Cu:

V

Q345A

0.12-0.2

0.20-0.6

1.00-1.6

≤0.045

≤0.045

≤0.3

≤0.3

≤0.2

0.02-0.15

Q345B

0.12-0.2

0.20-0.6

1.00-1.6

≤0.04

≤0.04

≤0.3

≤0.3

≤0.2

0.02-0.15

Q345C

0.12-0.2

0.20-0.6

1.00-1.6

≤0.035

≤0.035

≤0.3

≤0.3

≤0.2

0.02-0.15

Q345D

≤0.18

0.20-0.6

1.00-1.6

≤0.03

≤0.03

≤0.3

≤0.3

≤0.2

0.02-0.15

Q345E

≤0.18

0.20-0.6

1.00-1.6

≤0.025

≤0.025

≤0.3

≤0.3

≤0.2

0.02-0.15

 

MECHANICAL PROPERTY OF Q345 SERIES STEEL

Materials

Tensile strength, Mpa

Yield strength, Mpa

Elongation

Q345A

490-675

≥345

≥21

Q345B

490-675

≥345

≥21

Q345C

490-675

≥345

≥22

Q345D

490-675

≥345

≥22

Q345E

490-675

≥345

≥22

 

They are not much different in chemical composition. It is worth noting that the Al of Q345C,D and E increased by 0.015, harmful elements P and S decreased successively, and the test temperature of low-temperature impact work was low and the price was higher.Q345 series steel has good mechanical properties, good plasticity and weldability, and is widely used in buildings, Bridges, vehicles, ships, pressure vessels, etc. From February 1, 2019, the Chinese standard canceled the Q345 steel grade and replace it with Q355, corresponding to the European standard S355.