Analysis of Bending Surface Cracks of Hot-Rolled Q450NQR1 Steel Plate
In order to analyze the causes of cracks on the surface of Q450NQR1 steel plate af-ter bending,metallurgical microscope,scanning electron microscope,energy spectrometer and spectral analyzer were used to analyze the metallurgical organization,micro-morphology and types of inclusions and chemical composition of caracks of Q450NQR1 steel plate.The results show that the crack depth is about 40-50 μm,the presence of oxide dots at the bottom of the cracks,the obvi-ous decarburization of cracks near the surface,the presence of a large number of oxidation dots in the cracks that does not have evident banding.Therefore,it is considered that the matrix defects that cause cracks on the surface of the processed surface are not produced in the rolling process,but ex-ist in the casting billet.Further analysis shows that the defects may be due to the continuous casting billet sub-skin bubbles or near-surface micro-cracks,which are oxidized during the heating pro-cess before rolling,and then adhered to the surface of the steel plate after rolling,and then the de-fective area cannot participate in the synchronous deformation when bending and extending and eventually form surface crack defects.
万方数据
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