Q390GJC

Q390GJC is a high-strength steel plate specifically designed for building and construction applications. Its designation follows the Chinese national standard (GB) steel nomenclature system and is widely used in modern high-rise and super high-rise buildings, as well as large-span spatial structures. It is commonly applied in key load-bearing components such as columns, beams, trusses, connection plates, shear walls, and bridge supports. The "Q" stands for "Qu fu qiang du" (yield strength), indicating that the steel's primary mechanical property is defined by its yield strength. "390" denotes the specified minimum yield strength of 390 MPa at room temperature, significantly higher than that of ordinary structural steels, providing superior load-bearing capacity. "GJ" is the pinyin abbreviation for "Gong Jian Jie Gou" (building structure), clearly identifying its dedicated use in structural construction, distinguishing it from general-purpose or shipbuilding steels. The suffix "C" indicates the quality grade, meaning the steel must meet a minimum average absorbed energy of 27 J in Charpy V-notch impact testing at 0°C, ensuring adequate low-temperature toughness suitable for typical climatic conditions and enhancing structural safety under dynamic loads.

The main characteristics of Q390GJC steel plate include high strength, excellent weldability, good ductility and toughness, and high structural stability. Its chemical composition is based on carbon and manganese, with the addition of microalloying elements such as niobium, vanadium, and titanium. These elements enhance strength through grain refinement and precipitation hardening, while maintaining a low carbon equivalent (CEV) to ensure good weldability. It is compatible with various welding processes, including manual metal arc welding (SMAW), submerged arc welding (SAW), and gas metal arc welding (GMAW), producing stable, crack-resistant weld joints. The steel is typically produced via controlled rolling or normalization, resulting in fine grains and a uniform microstructure with consistent mechanical properties. The tensile strength ranges from 510 to 660 MPa, with elongation (A) ≥20%, providing excellent plastic deformation capacity. This enables effective energy absorption under seismic or other dynamic loads, improving the seismic performance and ductility of building structures. Additionally, Q390GJC exhibits good hot and cold workability, facilitating fabrication into complex shapes.

Q390GJC is widely used in the main structural systems of large public buildings with high seismic requirements, such as high-rise buildings, stadiums, exhibition centers, transportation hubs, and industrial workshops. Compared to Q345GJ series steels, Q390GJC offers higher strength, allowing for reduced member weight, lower steel consumption, and decreased overall building mass, thereby improving structural economy and seismic performance—especially in long-span and heavy-load structural systems.

The current standard for Q390GJC steel plate is the Chinese national standard GB/T 19879-2023 "Steel Plates for Building Structures", released and effective in 2023, replacing the previous GB/T 19879-2015 edition. This standard comprehensively specifies grades, chemical composition, mechanical properties, technological properties, impact toughness, thickness-direction properties (Z-direction properties), and inspection rules, serving as a key technical reference for structural design and construction. Due to its excellent overall performance, Q390GJC has become an indispensable high-strength structural material in modern building engineering.

目前，Q390GJC钢板执行的最新标准为中华人民共和国国家标准 GB/T 19879-2023《建筑结构用钢板》。该标准于2023年发布并实施，替代了旧版GB/T 19879-2015，对建筑结构用钢的牌号、化学成分、力学性能、工艺性能、冲击韧性、厚度方向性能（Z向性能）及检验规则等作出了全面规定，是建筑钢结构设计与施工的重要技术依据。因其优异的综合性能，Q390GJC已成为现代建筑中不可或缺的高强度结构材料之一。