Q390GJCZ15 steel plate is a high-strength structural steel plate with good welding performance and corrosion resistance, widely used in high-rise buildings, large public facilities, bridge engineering, marine engineering, wind power, and nuclear power projects. The execution standard for Q390GJCZ15 steel plate is GB/T 19879-2015. Its chemical composition mainly includes carbon, silicon, manganese, phosphorus, sulfur, copper, nickel, chromium, molybdenum, and other elements, meeting the requirements of relevant Chinese standards.

The Z-direction performance of Q390GJCZ15 steel plate refers to its mechanical properties in the thickness direction, reflecting its resistance to lamellar tearing. Z-direction performance is divided into three grades: Z15, Z25, and Z35. Among them, Z15-grade steel plate has good resistance to lamellar tearing and is suitable for structural components subjected to tensile loads in the thickness direction.

The price of Q390GJCZ15 high-rise building steel differs from that of ordinary Q390GJC steel plate. This is because, during the production process of Q390GJCZ15 steel plate, special heat treatment processes such as hot rolling and normalizing are required to meet its Z-direction performance requirements. Additionally, the chemical composition control for Q390GJCZ15 steel plate is stricter, requiring sulfur content to be controlled below 0.001% to reduce inclusion defects and improve resistance to lamellar tearing. These factors contribute to the higher production cost of Q390GJCZ15 steel plate, resulting in a price increase compared to ordinary Q390GJC steel plate.

The specific price difference needs to be determined based on market conditions and supply-demand relationships. Generally, the price of Q390GJCZ15 steel plate may be 300 RMB/ton to 1000 RMB/ton higher than that of ordinary Q390GJC steel plate. The exact price should also refer to the specific quotations from steel mills and actual market demand.

In summary, the price of Q390GJCZ15 high-rise building steel differs from that of ordinary Q390GJC steel plate, mainly due to its higher production costs, including special heat treatment processes and strict chemical composition control. The specific price difference needs to be determined based on market conditions and supply-demand relationships.