Effect of secondary cooling electromagnetic stirring on the microstructure and properties of wear-resistant steel
In order to study the effect of electromagnetic stirring with secondary cooling roller on the microstructure and properties of wear-resistant steel,the microstructure,inclusions and mechanical properties of 250 mm thick continuous casting billet and 20 mm thick steel plate were analyzed.The results show that the inner quality of the billet is obviously different between electric stirring and non-electric stirring,the center segregation is 1.0 and 3.0,the middle crack is 0 and 0.5,but there is no delamination and crack inside the steel plate after high compression ra-tio rolling.The particle scanning by AZTEC of Oxford found that the purity of electric stirred steel was better,but the inclusion size of non-electric stirred steel was more uniform.In addition,the number of small size inclusions of 1-5 μm in the thickness of 1/4 of the electrostirring steel is higher,so that the average equivalent diameter is lower than 0.32 μm without electrostirring.The average equivalent diameter of the core is higher than that without stirring by 0.49 μm because of the large size inclusions of 20-35 μm.The impact energy change in the direction of steel plate thickness is basically consistent with the inclusions distribution trend,and the toughness is better with the smaller the size.The cross section hardness uniformity of non-stirred steel is better,and the core hardness is high-er.According to the quantitative analysis of cross-sectional XRD,the volume fractions of residual austenite without and with electric stirring are 3.1％and 3.4％,respectively,and there is more martensitic phase without electric stirring.In this paper,the hardness range of electric stirred steel and non-electric stirred steel is 15 HV and 25 HV respectively,which is far lower than the upper limit requirement of the standard,and has no obvious effect on the cold bending performance of D=4a.
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