Papers by Keyword: Q370qE

Abstract: The flaws in a heavy bridge-making steel plate (Q370qE) were detected by ultrasonic test, the types and formation reasons of which were studied by metallographic examination, scanning electron microscope (SEM) and energy dispersive X-ray (EDX) spectrometer. The results showed that the types of the flaws were mainly crack, micropore and inclusion. The formation of crack and micropore was attributed to the center segregation, porosity, as well as the role of structural stress and thermal stress. Moreover, the inclusions were mainly composite oxides (MgO, Al₂O₃, CaO, etc.) and MnS, the former came from the raw materials and impurity oxides, however, the latter came from the center segregation of the alloying elements. Besides, some improvement measures to reduce detecting flaws were also proposed.

Abstract: According to the BS7448 fracture toughness test standard and DNV-OS-C401,this dissertation conducted a CTOD(crack tip opening displacement) fatigue crack precast test with the used steel Q370qE in bridge.Respectively tested different thickness mather materials’condition of fatigue crack,and analysis the test’s results,thus obtained the related conclusions.