The Specification of Q460B High Strength Carbon Steel Pipe

The letter Q represents the yield strength ("Qu" in Chinese pinyin), while 460 indicates that the steel has a minimum yield strength of 460 MPa.
MPa (megapascal) is a unit of pressure, where mega equals 10⁶.

Therefore, Q460 means that the steel pipe will begin to undergo permanent (plastic) deformation only when the applied stress reaches 460 MPa. Once the external load is removed, the pipe cannot return to its original shape.

This strength is significantly higher than that of ordinary carbon steel pipes.

To maintain a low carbon equivalent (CEQ) and ensure good weldability, Q460 steel increases the content of microalloying elements (such as V, Nb, Ti) in a controlled manner.

These elements improve strength through grain refinement and precipitation strengthening. Although microalloy additions slightly increase the carbon equivalent, the overall CEQ remains low enough to preserve excellent welding performance.

Grade Designation Method (for Pipes)

The grade designation for Q460 steel pipes consists of three parts:

Example: Q460C

Q - Indicates the yield strength ("Qu" in Chinese).

460 - Yield strength value in MPa.

C - Quality grade (categories: C, D, E).

If thickness-direction performance (Z-direction) is required for the pipe material, a Z-grade symbol can be added:

Example: Q460CZ15

Chemical Composition of Q460 (for Pipe Manufacturing)

(Mass fraction %)

(Note: Q460D and Q460E have stricter P and S limits to enhance toughness and low-temperature performance.)

Mechanical Properties (for Q460 Pipe)

Yield Strength Requirements

≤16 mm: ≥460 MPa

16–40 mm: ≥440 MPa

40–63 mm: ≥420 MPa

63–80 mm: ≥400 MPa

80–100 mm: ≥400 MPa

100–150 mm: ≥380 MPa

Tensile Strength

550–720 MPa

Elongation

≥17%

Impact Performance

0°C Charpy V-notch impact energy ≥34 J