| The fracture behaviours of two structural steel (Cr-Mn-Mo steel,Cr-Ni-Mo-Vsteel) under high speed shock ( detonation wave loading ) have been investigated by means of metallography,scanning electron microscope ( SEM ) .It included structure of steel observed by scanning electron microscope and measured rigidity and fractal.It is shown by the results that two steel fracture are damage evolution process , and obtain its fracture mechnisms. Cr-Mn-Mo steel fracture mechanism : microcracks nucleate in inclustions , its propagation and coalescence induce fracture . Cr-Ni-Mo-V steel fracture mechanism : cross point of three grain-boundary is crack source , cracks propagate along small grain direction , lead to fracture ; secondly .Split to have still having of the influence to the structure steel:Shearing to slice to take is the early sign of the end breakage, cutting off the heat shear to slice to transform is one kind to transform appearance harmfully, the dynamic state splits and cuts off heat to shear to slice to take closely related, and usually follow to shear to slice to take to pierce through to open crack;The amount, size in the material, distribute the function which splits to the dynamic state of material is very and important.Made use of a method of dividing the form to carry on quantitative analysis towards breaking, discover score dimension and material microstructural are germane, the critical crack expands size and area scope of dint and cent dimension relevant.The layer crack section is a cent form, this layer crack's breaking facial look can use the cent dimension in a mark degree area scope fixed amount to depict;Layer the cent dimension which splits a section's combining is much more than a simple number, closely-related with microstructural;Say for same material, the dissimilarity pounds at speed a bottom, dividing dimension a dissimilarity;The score dimension of cross section can be a parameter of material function to carry on quantitative analysis. |
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