Analysis of the Reasons and Risks of Reducing the Performance of the Teeth of the Buckets of Quarry Excavators in the Conditions of Excavation of Frozen Soils in the Arctic Region

The gradual migration of production facilities of companies that extract minerals to the permafrost zone of the Arctic and Subarctic regions of the Russian Federation has revealed a number of problems in the operation and maintenance of mining equipment, primarily excavators and loaders, which account for about half of the volume of work in solid mineral deposits. One of these problems is a sharp decrease in the service life of the teeth and crowns of the buckets. While the average service life of this tool can be several months in middle latitudes, it can be reduced to a few days in northern conditions. The paper analyzes the causes of accelerated wear of the teeth of excavator buckets due to metallurgical defects and imperfections in the metal structure. Analysis of the failed crowns showed that the main reason, in addition to product wear, is the development of fatigue cracks in the working part of the crowns. It was shown that the castings of damaged crowns contain a signifi cant number of casting defects, such as hot cracks, large pores, and casting liquation of the main alloying and impurity elements, and subsequent heat treatment does not eliminate these defects. It has been established that the main cracks that lead to the destruction of crowns have two sections: the crack focus is a large casting pore or a hot crack, which develops according to the fatigue mechanism in a plane perpendicular to the surface of the crown during operation. A metallographic analysis of the structural inhomogeneities of the crowns’ metal, an analysis of the chemical composition of the metal solid solution, and the inclusion of excess phases present in the steel, has been performed. It has been shown that in order to improve the performance of the crowns during excavation of frozen rocks, it is necessary to optimize the casting technology and subsequent heat treatment of the castings.