Image Analysis And Mechanical Simulation Of Cemented Carbide Microstructure

Cemented carbide is a composite material composed of a hard phase WC and a cohesive phase Co with a large difference in properties.Therefore,the mechanical performance has important influence on the number of receptors,grain size,adjacency,and grain distribution.Therefore,the microstructure characterization of WC-Co Cemented carbide is very important.In traditional two-dimensional microstructure characterization,linear interception on scanning electron micrographs(SEM)is to determine carbides in WC-Co Cemented carbide.The most common measurement method for grain size and contiguity,but this requires tedious and subjective measurements and is strictly dependent on the quality of micrographs and the definition and definition of grain boundaries.In the research of this thesis,the automatic image analysis program with two key technologies has been successfully developed,namely the maximum category variance method and the improved watershed algorithm.It is easy to analyze the image of WC-16 Co hard alloy by this method.Obtain consistent microstructure parameters.The results obtained are then compared with the values obtained by the linear intercept technique.Based on the results of the experiment,a series of empirical relationships were found.Whether it is the linear intercept method or the area method,the change of the WC grain size and the average free path of the Co binder have almost no effect on the cemented carbide abutment;the average grain size of the WC and the average free path of the Co binder is linearly related;the hardness of the cemented carbide is linearly related to the inverse of the square root of the average grain size of the WC,and is consistent with the model of Chermont and Osterstock.Although it has not yet been determined that the WC average grain size(and the subsequent mean free path ?)measured by the stub method and the area method,that effect is better.However,through the study of this paper,the mean grain size of WC and the mean free path of Co binder obtained by the area method compared with the stub method are more consistent with the hardness models of Chermont and Osterstock.Although it is difficult to find out which method is more appropriate,it is necessary to study the key parameters obtained by t he two methods,which can better explain the microstructure of the alloy and the mechanical behavior modeling of the cemented carbide.In this paper,the stress and strain of the microstructures of WC-Co composites with 4 different grain sizes under tensile load were numerically analyzed by the finite element method.The statistical results are used to simulate the equivalent Young's modulus and its equivalent Poisson's ratio.The obtained parameters are in accordance with the models of Hashin-Shtrikman and Zimmerman,respectively,and thus the consistency of the conclusion is proved.The accuracy of the area method was explored and solved from the technical level,which provided a new idea and new method for the microscopic parameter simulation of WC-Co Cemented carbide.