Research On The Mechanical Properties Of Q345 H-beam For High Rise Building Applications

Steel structure is becoming the future trend of the development of construction industry because of its light weight and high strength, but steel structure building in China accounts for only about 4% of the all the constructions, therefore there are broad prospects for development for our country’s steel structure building. H-beam which based on the composition of Q345 has more reasonable cross-section and less internal stress. It can greatly reduce the weight of the building structure compared with the ordinary beams because it can save more metal and it’s lighter than ordinary beams. Lamellar tearing of steel sheet is along the rolling direction in its internal stress of cracking. There are large constraints and welding quantity in weld thickness direction for many large structures, therefore the risk of lamellar tearing in welding place is very large. Therefor lamination crack resistant steel must be used for this kind of structure.The subjects mainly use the method of comparing. We compared the Q345B which with the refining to the Q345B which without refining in many aspects like composition, microstructure, mechanical properties and inclusion. At the same time we compared the Z direction performance of different position on the same steel flange. We use universal testing machine to test the material’s mechanical properties, use the metallographic microscope to observe the microstructure of materials, use scanning electron microscope and energy dispersive spectroscopy to observe materials inclusions and its components.Through the study we can find that both of the steel’s Z direction properties are better than the nation’s highest standards. However the Q345B which with the refining performs better Z direction properties than the Q345B which without the refining, the reason is mainly because after refining the content of sulfur decreased significantly, the manganese sulfide inclusions which has deeply influence on performance of Z direction reduced. And in the same kind of steel flange on different parts of the perpendicular to the rolling direction, the flange 1/3 place has the best Z direction properties, the reason is that in 1/3 we can ignore the influence of the angular position and the spread on the edge.