| Due to the particularity and complexity of the preparation process,the distribution of composition and microstructure of large-size metal casting and forging components has non-uniform characteristics,and these inhomogeneous distribution will lead to different physical and chemical properties of the components in different positions.it not only destroys the continuity of matrix structure and performance,but also has an important impact on the service behavior of materials,which may lead to shortening the service life of components or even directly scrapping them.Therefore,the realization of large-scale and multi-scale fine distribution characterization of composition and microstructure of large-size metal casting and forging components is not only beneficial to analyze the distribution characteristics of material composition and structure,but also lays a foundation for the construction of material quality evaluation system,optimization of material preparation process and material modification.In this paper,two kinds of large-size metal components,superalloy cast-forged GH4096 turbine disk and low and medium alloy steel train wheels,are studied by studying the fluorescence spectrum behavior of elements under different test conditions.the element quantitative method is corrected by introducing type-matched bulk spectral control samples,and a nondestructive,original position statistical distribution characterization method based on multi-channel capillary focusing-microbeam X-ray fluorescence spectrum composition is established.Eight major elements Cr,Co,Mo,W,Ti,Al,Nb and Ni in the turbine disk are analyzed in situ,and the composition distribution rules of different parts of the turbine disk are obtained.it is found that there is a narrow arc negative segregation zone of Co,Mo and Ti in the center of the thickness of the turbine disk from the hub to the flange,while the two elements Ni and Cr are positive segregation here,but have little effect on the statistical results of the content in the whole region.There is also a certain composition gradient distribution in the radial direction of the turbine disk.The contents of Co,Cr and W decrease gradually from the hub to the flange,while the contents of Mo,Ti and Nb increase gradually.Through the quantitative statistical analysis of the maximum segregation degree,statistical segregation degree and statistical coincidence degree of each element in the scanning area,it is found that most of the elements in the turbine disk show a good normal distribution,and all the content data are within the allowable range of the turbine disk composition.At the same time,microbeam X-ray fluorescence spectrometry is also applied to characterize the distribution of main elements in low and medium alloy steel train wheels.It is found that there are great differences in element distribution in different regions of the wheel,in which the signals of Mn and S elements in the hub part are more obvious than those in other parts,which may be caused by the accumulation of large-size manganese sulphide inclusions.In this paper,an in-situ statistical quantitative distribution characterization method of inclusions in large-size components based on scanning electron microscopy(SEM)and high performance energy spectrum analysis(EDS)is established.The type,quantity,size and distribution of inclusions in M,T and E wheels produced by different preparation processes were quantitatively analyzed in situ by this method.It is found that there are great differences in the composition and distribution of inclusions in different process wheels.In the rim area of the wheel,the inclusions in M wheels are mainly strip sulfides and spherical sulfides,and most of the strip sulfides are more than10 microns;the inclusions in T wheels are mainly spherical sulfides and oxygen-sulfur complexes,in which the number of spherical sulfides with a size of 3-5 microns is the most.The E wheel is mainly composed of oxide inclusions,the amount of strip sulfide inclusions is very small,and there are a small amount of oxide and oxygen-sulfur complex inclusions larger than 15 microns.There are also great differences in the distribution of inclusions in different parts of the same wheel,in which the area fractions of strip sulfides and spherical sulfides in the hub of M and T wheels are much higher than those in the spoke plate and rim,and the oxide area fraction in the hub of E wheels is higher than that in other parts.The oxides larger than 10 microns,spherical sulfides and strip sulfides in M and T wheels accumulate most in the hub,while there are more oxides larger than 15 microns in the hub of E wheels,but relatively few in the spoke area.At the same time,this paper also discusses the correlation between the abnormal spectral signals of Mn elements in the same area of the wheel and the number,size and total area of Mn inclusions.It is found that the total intensity of abnormal fluorescence signals of Mn elements is closely related to the total area of particles with Mn inclusions larger than 8 microns.With the increase of the total area of large particles containing Mn inclusions,the total intensity of abnormal fluorescence signals of Mn elements increases gradually.The distribution of elements in the same region was characterized by metal in-situ analyzer,and it was found that there was a linear relationship between the frequency of simultaneous abnormal spark spectral signals of Mn and S elements and the total area of manganese sulphide inclusions,and that the frequency of simultaneous abnormal spectral signals of Al,Mn and S elements was also related to the total area of oxygen-sulfur composite inclusions... |
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