中美建筑钢结构钢材性能对比分析

Performance Comparison of Structural Steels in Chinese and American Standards

详尽梳理和对比了中美建筑钢结构标准中常用钢材产品的性能,包括国标Q235~Q460钢、美标ASTM A36(M)、ASTM A572(M)钢、耐候结构钢及铸钢在化学成分、屈服强度、抗拉强度、冲击韧性、断后伸长率和冷弯性能等方面的性能指标及试验方法的异同。分析发现:国标对钢材化学成分的规定更详细,可焊接性能较好;国标中常用的碳素钢和低合金高强度结构钢的力学性能随钢板厚度的增加而递减,相应的美标钢材力学性能则保持不变;国标Q235、Q235GJ钢的抗拉强度比同级别的美标A36钢材低6%以上;板厚不大于40 mm的国标Q355钢材及板厚不大于50 mm的国标Q345GJ钢的力学性能均高于美标的A572 GR50钢;板厚不大于40 mm的国标Q390钢材及板厚不大于100 mm的国标Q390GJ钢的力学性能均不低于美标的A572 GR55钢;国标Q420、Q420GJ和Q460、Q460GJ钢材的力学性能均不低于美标相应级别的A572 GR60钢和A572 GR65钢;中美标准中耐候钢的耐候性指数均大于6.0,但化学成分的规定不同,国标耐候钢的牌号更多、强度覆盖范围更大,厚度不大于40 mm的国标耐候钢力学性能不低于相应级别的美标钢材;国标的铸钢牌号更多,强度级别的覆盖范围更大;铸钢试件的力学性能采样标准试块不同,美标的标准试块厚度更大。

The differences and similarities in the performance and test methods of steel products commonly used in Chinese standards(GB)and American Society for Testing and Materials(ASTM)standards,GB Q235-Q460 steel in,ASTM A36(M),ASTM A572(M)steel,structural steel with atmospheric corrosion resistance and cast steel in chemical composition,yield strength,tensile strength,impact toughness,elongation after fracture and cold bending performance were compared and summarized in detail.The analysis results show that Chinese steel standards have more detailed provisions on the chemical composition,and the welding performance is better.The yield strength of common used carbon steel and high-strength low-alloy steel decreases with the increase of the thickness of the steel plate,but the corresponding mechanical properties of the steel in ASTM will remain the same.The tensile strength of GB Q235 and Q235GJ steel is more than 6% lower than that of ASTM A36 steel.The mechanical properties of GB Q355 steel whose thickness is no more than 40 mm and GB Q345GJ steel whose thickness is no more than 50 mm are higher than those of ASTM A572GR50 steel.The mechanical properties of GB Q390 steel with thickness of no more than 40 mm and GB Q390GJ steel with thickness of no more than 100 mm are not lower than those of ASTM A572GR55 steel.The mechanical properties of GB Q420,Q420GJ,Q460 and Q460GJ steels are not lower than those of ASTM A572GR60 and ASTM A572GR65 steels respectively.The atmospheric corrosion resistance indexes of weathering steel of Chinese and American standards are both greater than 6.0,but the chemical composition is different.The number of grades for GB weathering steel is more;the strength coverage is larger;and the mechanical properties of GB weathering steel with thickness of no more than 40 mm are not lower than those of the corresponding grade of ASTM steel.The GB cast steel has more steel grades and the coverage of strength grade is larger.The mechanical properties of cast steel specimens are different in shape and thickness,and the ASTM specimens are thicker.