Differences between Q345GJZ and Q345GJ steel plates

Q345GJZ is a special steel plate for high-rise building structures that must have Z direction (Z12, Z25, Z35).

Q345GJ is a structural steel for high-rise buildings. It is not necessary to specify the Z-direction (Z12, Z25, Z35) test unless ordered.

The chemical composition S of Q345GJZ and Q345GJ steel plates is different:
The S content of Q345GJZ is as follows:
Z-direction performance grade Z15 Z25 Z35 sulfur content (%), not more than 0.01 0.007 0.005 respectively.

The S content of Q345GJ is specified in GB/T19879 without Z-direction (Z12, Z25, Z35) requirements. Under the requirements of Z direction (Z12, Z25, Z35), the S content is the same as that of Q345GJZ.

Q345GJZ and Q345GJ steel plates have different uses:
Q345GJZ requires not only certain mechanical properties along the width and length directions, but also good layered tear resistance in the thickness direction. The lamellar tear resistance of steel plate is evaluated by the reduction of area of the tensile test in the thickness direction. It is used for some important welding components such as high-rise buildings, shipbuilding, offshore oil production platforms, boilers and pressure vessels.

Q345GJ is used to manufacture high-rise building structures, large-span structures and other important building structures. If required, Z direction (Z12, Z25, Z35) can be made, which is the same as Q345GJZ.