How to distinguish Q345GJZ from Q345GJ steel

Different purposes
Q345GJZ steel 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. Q345GJZ steel is used for some important welding components such as high-rise buildings, shipbuilding, offshore oil production platforms, boilers and pressure vessels.

Q345GJ steel 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 steel.

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

Q345GJZ is a special steel plate for high-rise building structure with 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.