Study On Mechanical Properties Of Q460GJC Thick Plate And Its Weld Joint

With the development of the construction industry,many countries are actively developing high strength and high performance steel.In order to meet the needs of China's construction industry and maintain the competitiveness of China's engineering technology,Chinese companies like Henan Wuyang Iron and Steel Co.,Ltd.have developed and improved the domestic high performance construction steel-GJ steel.At present,high strength GJ steel has been used in many domestic large-scale construction projects.Since most of these projects involve high-rise and large-span structures,the design thickness of steel plates is uaually large.Under the support of the National Natural Science Foundation Project(No.51578089),mechanical properties of Q460 GJC thick plate and its weld joint are studied.The main contents and conclusions of the study are as follows:(1)Static properties of the material in transvers and Z direction at diferent thickness of Q460 GJC plates of the thickness of 25 mm,42mm and 80 mm are studied and the static constitutive relation is discussed.The results show that the areas nearer to the outer surface of the thick plates are with higher strength and better ductility.RambergOsgood model modified by Rusmussen's formula can well simulate the monotonic stretching curves of the material of Q460 GJC thick plates at diferent thickness.(2)Low cyclic properties of the material in transvers and Z direction at diferent thickness of Q460 GJC plate of the thickness of 80 mm are studied and the finite element analysis is carried out.The results show that Q460 GJC thick plate has good seismic energy dissipation performance.The areas nearer the outer surface of the thick plate are with higher cyclic strength.After cyclic loading,the transvers upper-layer specimens undergo strain softening and the rest of the specimens undergo varying degrees of strain hardening.The simulation results of the cyclic loading obtained by the hybrid reinforcement model in ABAQUS are in good agreement with the experimental values.(3)Static properties of the material at different thickness of the butt weld of Q460 GJC box section of the thickness of 80 mm are studied.The results show that the strength of the middle and lower layers(inner surface of the box section)of the weld zone is higher than that of the upper layers(outer surface of the box section).The strength of the upper and lower layers of the heat affected zone is higher than that of the middle layers.(4)Fatigue properties of the material at different thickness of the butt weld of Q460 GJC box section of the thickness of 80 mm are studied and are compared with the steel codes in China,USA and Europe.The results show that the fatigue strength of the middle layers is higher than that of the upper layers.The accumulation rate of fatigue damage in the middle layers is less than that in the upper layers.The fatigue strength of both the middle and the upper layers is far higher than the calculated values of the steel codes in China,USA and Europe.The accumulation rate of fatigue damage in both the middle and the upper layers is smaller than the calculated values of the steel codes.The innovations in this article are as follows:(1)The variation of static and low cyclic properties of the material in transvers and Z direction at diferent thickness of Q460 GJC thick plate is studied.(2)The variation of static and fatigue properties of the material at different thickness of the butt weld of Q460 GJC box section of the thickness of 80 mm is studied.