| The quality requirement of bearing steel, as a kind of special steel, is the most strict one in steel production, and carbide is an important evaluation to the performance of bearing steel. The performance of bearing steel is mainly evaluated by visual observation and manual examination early, but these methods have their limitations: heavy labor intensity, low efficiency. With good repeatability and high processing accuracy, it is necessary to apply digital image processing technology to the analysis of metallography.Digital image processing technology is introduced to evaluated the carbide distribution of different parts of bearing steel for several typical heat-treatment based on related theory of digital image in this thesis, which makes the analysis of bearing steel’s performance more faster and precise. The main research contents and results are as follows:(1) The development of quantitative analysis of metallography at home and abroad, and the significance of applying digital image processing technology to the carbide analysis of bearing steel are summarized.(2) The methods of gray level transformation, image segmentation and morphological image processing are proposed for the metallography of GCr15 bearing steel based on the basic knowledge of digital image processing, and the reasonable processing method for the metallography of GCr15 bearing steel was selected according to its gray histogram after treatment and its image quality.(3) The carbide particle’s edge information of GCr15 bearing steel was extracted by proposed a new modified method from traditional Sobel algorithm, and the carbide particle was also extract through the morphological image processing methods like expanding corrosion and region filling, which laid a foundation for carbide analyzing of metallography.(4) The metallography was blocked randomly based on Open CV, and its carbides distribution was analyzed by principle of least square method, which realized the statistical analysis of the carbide distribution in bearing outer ring and roller of GCr15 bearing steel, and the results were obtained. The results showed that the carbide homogeneity of this sample can meet its operating requirements.The performance analyzing of bearing steel was combined with digital image processing technology in this thesis, and the metallography of GCr15 bearing steel was processed by digital image processing technology, which could realize thestatistical analysis to the carbide homogeneity of metallography. The research results have a practical meaning to the digital analysis of meatllography. |
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