Q420GJDZ15 steel plate is a high-strength construction structural steel plate with good toughness and wear resistance. Its Z-direction performance refers to the mechanical properties of the steel plate in the thickness direction, mainly including tensile strength, yield strength, and impact absorption energy. The Z-direction performance of Q420GJDZ15 steel plate has the following advantages:

1. High tensile strength: Q420GJDZ15 steel plate has a high tensile strength, allowing it to withstand significant tensile stress. This gives the steel plate better load-bearing capacity and stability in building structures, making it suitable for large-scale engineering structures such as high-rise buildings and bridges.

2. Suitable yield strength: The yield strength of Q420GJDZ15 steel plate varies within a certain range, with a good yield-to-tensile ratio, enabling the steel plate to exhibit better plastic deformation capacity under stress. This helps improve the safety performance of the steel plate in building structures and reduces the risk of brittle fracture.

3. High impact absorption energy: Q420GJDZ15 steel plate has high impact absorption energy, indicating that it possesses good toughness and wear resistance when subjected to impact loads. This gives the steel plate better fatigue resistance in building structures and extends the service life of the structure.

4. Good low-temperature performance: Q420GJDZ15 steel plate maintains a high level of Z-direction performance in low-temperature environments. This makes it suitable for applications in cold regions and low-temperature environments.

5. Excellent welding performance: Q420GJDZ15 steel plate has good welding performance, ensuring that the strength and toughness of welded joints meet requirements. This facilitates the welding processing of building structures and improves construction efficiency and quality.

6. Corrosion resistance: Q420GJDZ15 steel plate exhibits good corrosion resistance under certain conditions, enhancing its durability in building structures.

7. Mature production process: Q420GJDZ15 steel plate is produced using processes such as hot rolling, normalizing, and tempering, which ensure good Z-direction performance and overall quality of the steel plate.

In summary, the advantages of Q420GJDZ15 steel plate's Z-direction performance include high tensile strength, suitable yield strength, high impact absorption energy, good low-temperature performance, excellent welding performance, corrosion resistance, and mature production processes. These advantages make Q420GJDZ15 steel plate widely applicable in the field of building structures. In practical engineering, selecting the appropriate steel plate thickness, specifications, and welding processes based on specific design requirements and construction conditions can ensure the safety, reliability, and durability of building structures.